Car wheel borer with transfer mechanism

Abstract

Claims

1. IN A MACHINE TOOL PERFORMING A WORK OPERATION UPON A CIRCULAR WORKPIECE; A BASE; A TOOL HEAD SUPPORTED ON SAID BASE; A CUTTER ROTATABLY SUPPORTED IN SAID TOOL HEAD; A WORK FIXTURE MOUNTED ON SAID BASE; SAID TOOL HEAD AND SAID WORK FIXTURE BEING CONSTRUCTED AND ARRANGED SO AS TO PROVIDE FOR RELATIVE MOVEMENT THEREBETWEEN; A WORKPIECE GUIDE SECURED TO SAID BASE AND DISPOSED BETWEEN SAID TOOL HEAD AND SAID WORK FIXTURE TRANSVERSELY OF SAID BASE IN POSITION TO ROTATABLY GUIDE A WORKPIECE INTO A PREDETERMINED WORK POSITION BETWEEN SAID TOOL HEAD AND SAID WORK FIXTURE; A TRANSFER MECHANISM CARRIED BY SAID BASE AND OPERABLE TO ROLL A WORKPIECE INTO THE WORK POSITION AND A FINISHED WORKPIECE OUT OF THE WORK POSITION SIMULTANEOUSLY; A CHUCK MECHANISM CARRIED BY SAID WORK FIXTURE AND OPERABLE TO RECEIVE AND CLAMP A WORKPIECE IN THE WORK POSITION TO SAID WORK FIXTURE; A BACKING PLATE YIELDABLY
June 15, 1965 A. H. FoTscH ETAL 3,188,890 CAR WHEEL BORER WITH TRANSFER MECHANISM Filed Feb. 6, 1958 7 Sheets-Sheet 1 INVENTORS 092th? M 1013071, John ,0. finley Gzibcet N Bass, Etchaed i mschela J1me 1965 A. H. FOTSCH ETAL 3,188,890 CAR WHEEL BORER WITH TRANSFER MECHANISM Filed Feb. 6, 1958 '7 Sheets-Sheet 2 IN VEN TORS Ii/2111112 i iatsrlz; 1/0111: 8. mniey Gzibeet 141E035, manned 7( 11:01:22 4mm 22 e Z 7 Sheets-Sheet 3 A. H. FOTSCH ETAL CAR WHEEL BORER WITH TRANSFER MECHANISM 35 @8 mmm nmm mmm June 15, 1965 Filed Feb. 6, 1958 June 15, 1965 A FQTSCH ETAL 3,188,890 CAR WHEEL BORER WITH TRANSFER MECHANISM Filed Feb. e, 1958 7 Sheets-Sheet 4 INVENTORS q flelhuz H =flalsch, John 9, imiey Gilbeet M Ross, BiChfl-Bd it m'schae June 15, 1965 A. H. FOTSCH ETAL CAR WHEEL BORER WITH TRANSFER MECHANISM 7 Sheets-Sheet 5 Filed Feb. 6, 1958 IN V EN TORS 42mm 11 1mm, an B. may bmm t qww Q E QQ N E Q Q June 15, 1965 A. H. FOTSCH ETAL CAR WHEEL BORER WITH TRANSFER MECHANISM 7 Sheets-Sheet 6 Filed Feb. 6, 1958 my m WNW J N h 2 m 0 m w 1| L m r\ v .3 l nw m Qm MM U mow F mmq QQ\ I l I N Q I 0 .1 c 1% l may v I X r\ M 3 Jm 7 miwfi I. u m 0 J 4 I 2 Rm 3\..) 13 3% \Q@ Mk 1 \h d I I k as huh gm mm Ev w 5 United States Patent 3,188,890 CAR WHEEL BORER WITH TRANFER MECHANISM Arthur H. Fotsch, Wauwatosa, John R. Finley, West Allis, Gilbert W. Ross, Brookfield, and Richard F. Fischer, Milwaukee, Wis, assignors to Kearney & Trecker Corporation, West Allis, Wis, a corporation of Wisconsin Filed Feb. 6, 1958, Ser. No. 713,573 22 Claims. (Cl. 77-3) This invention relates generally to machine tools, and in some of its aspects has more particular reference to a machine tool organization in which a workpiece may be supplied to the machine tool in a load or ready station and then automatically moved into a work position or station for the performance of a work operation and then moved out of the work station as another workpiece is moved into the work station. A general object of the present invention is to provide an improved machine tool for performing a work operation on a circular workpiece in an upright position. Another object of the present invention is to provide a machine tool organization wherein a circular workpiece may be automatically rolled into a work position while a finished workpiece is being rolled out of the work position. Another object of the present invention is to provide a machine tool organization wherein railroad car wheels of different sizes, indiscriminately supplied to the machine tool in an upright condition and requiring the performance of a particular machining operation thereon, will be automatically moved into a work position and held in predetermined relationship to a boring tool for the performance of a selected boring operation. Still another object of the present invention is to pro- 7 vide a machine tool having a fixture head and a tool head movable relative to each other and having means for guiding and rolling a railroad car wheel into a work position between the heads. Another object of the present invention is to provide a machine tool having a fixture head adapted to receive and hold a circular workpiece and which is provided with an axial recess into which a tool performing a work operation on the workpiece held in the fixture head, may extend without interfering With the operation of the tool or the fixture head. Another object of the present invention is to provide a production machine tool for boring the axial opening in railroad car wheels while the car wheels are maintained in an upright position. Yet another object of the present invention is to provide a machine tool which is automatically operable to move railroad car wheels of different sizes, supplied to the machine tool into a work position and having chucking means automatically engageable with a car wheel in the work position and operable to position and hold the car wheel in axial alignment with a tool for a selected work operation and after a work operation has been completed is operable to move the car wheel out of work position. Another object of the present invention is to provide a work fixture for a machine tool which is operable to position and hold a circular workpiece in a predetermined position and having means whereby at least one of the clamping elements is retractable so as to render the work "fixture accessible for supplying workpieces thereto. Another object of the present invention is to provide a work fixture which is operable to position and hold a circular workpiece in a predetermined position of alignment relative to a tool and which is automatic in its operation. According to this invention there is provided an improved machine tool especially adapted for boring the hub 3,l88,8% Patented June 15, 1965 of railroad car wheels wherein the car wheels are supplied to the machine tools and thereafter are automatically moved through the machine, without being handled by the operator. In the present embodiment, a single boring operation is performed on an individual car wheel. However, the car Wheels as supplied to the machine may be an intermixture of different sizes requiring a smaller or larger opening. The machine tool comprises, in general, a base having a chuck head movable thereon towards and away from a tool carrying head fixed to the base. The car wheels are supplied to the machine from an independent source in an upright position and are held in readiness in the machine to await movement into a Work position located between the two heads. A transfer mechanism is carried by the machine in position to engage a car wheel in the ready or load station and is operable to roll the car wheel into the work position or station. Upon completion of a transfer movement, the transfer mechanism trips a switch which causes the car wheel engaging members of the transfer mechanism to be moved out of engagement with the car wheel and after being so moved another switch is tripped which causes the chuck head to be actuated into a position so that a chuck mechanism carried by the chuck head is in position to clamp the car wheel to the head. When the chuck mechanism has been moved into position another switch is tripped which causes the chuck mechanism to clamp the car wheel to the chuck head. When the car wheel is fully clamped to the chuck head, the head will advance towards the tool carrying head thereby feeding the car wheel to the tool for the boring operation. Simultaneous with the boring operation the transfer mechanism will be returned to its initial position. After advancing a predetermined amount of travel, as initially selected by the operator, a switch will be tripped which causes the chuck head to be retracted at a rapid rate. When the chuck head has been returned to the workpiece line, a switch will be tripped, stopping the retraction of the head and causing the chuck mechanism to be unclamped. The chuck mechanism when fully released trips another switch which causes the chuck head to be fully retracted to its initial start position to complete a cycle of operation. When the operator initiates another cycle of operation the transfer mechanism will roll a workpiece from the load position into the work position and simultaneously will roll the finished workpiece out of the work position into a receiving position. The finished workpiece in the receiving position will be removed from the machine, as by gravity or conveyor means, while the machine is operting upon the new workpiece. The foregoing and other objects of this invention will become more fully apparent from the following detailed description, and may be achieved by the exemplifying apparatus depicted in and further described in detail in connection with the accompanying drawings, in which: FIGURE 1 is a view in front elevation of a machine tool embodying features of the present invention with parts broken away to show internal mechanism; FIG. 2 is a fragmentary view in right side elevation of the machine tool depicted in FIG. 1 showing the tool drive and the arrangement of the backing plate supporting arms; FIG. 3 is an enlarged View of the fixture head, partly in vertical section and partly in side elevation, showing the internal mechanism of the chuck mechanism; FIG. 4 is a transverse view of the machine tool of FIG. 1 taken along the line 4-4 of FIG. 1, showing the transfer mechanism and the arms thereof for rolling the workpieces into position in the machine and the clamping jaws of the fixture head; FIG. 5 is an enlarged fragmentary view partly in elevation and partly in vertical section taken along the plane a represented by the line -5 in transfer mechanism; FIG. 6 is a view of the fixture head in left side elevation with parts broken away to show the details of the actuating arms of the chuck jaws; i i i I FIG.- 4 to illustrate the FIG. 7 is a diagrammatic view illustrating the hydraulic FIG. 10 is an enlarged view of the fixture head em- 7 ployed in the modified form of the'invention, substantially in vertical section taken along'the line 10,10 of FIG. 9, with one of the lower jaw assemblies being rotated so as to appear in a vertical plane to more clearly illustrate the operating arrangement for retracting the jaw. Referring more specifically to the drawings and particularly to FIG. 1 thereof, the invention is shown embodied ina horizontal boring machine for boring the axial opening in railroad car Wheels. while maintaining the wheels in an upright position and comprising, in general, a base on one end of which is supported a chuck or fixture head 16 for longitudinal movement. The'fixture head 16, as shown in FIGS. 3' and 6, has an end or face plate 17 and a pair of upstanding sloping side walls 18 and 19 which are integrally formed with the end plate 17 and extend rearwardly thereof. To guide and support the fixture head 16in its path of travel the base 15 'is provided with a pair of integral guide'ways22 and 23 formed in the fixture head. To actuate the fixture head wheels rated at and 50 tons. For the axial opening in car wheel's rated at 70 tons, another set of cutters 46 are provided on the boring bar 39 for boring a hole of greater diameter; The set of cutters 46 are spaced rearwardly of the cutter set a sufiici'ent distance so that when the head 16 is advanced to feed a 70 ton car wheel to the set of cutters '46 the set of cutters 45 will pass through the rough axial opening in the car wheel and extend clear of the car wheel before the set of cutters 46 operate upon the car wheel. ' It is to be noted that in the particular illustrative machine, the chuck head 16 is described as being movable and the spindle head 35' is described as being fixed so that the chuck head moves towards the spindle head. This relationship of movement between the two head 'membersmay be reversed by rendering the spindle head 35 movable and fixing the chuck head 16 to the base 15. Extending transversely of the base 15, between the fixture head 16 and the spindle head 35, is a pair of Workpiece guide-and supporting rails 47 and 48. As best shown in'FIG. 4, the. bottom rail 47v is supported on a pair of laterally extending 'outriders or frame members and 51. The'frame members 50 and 51 are welded or otherwise secured to the sides of the base 15 and extend outwardly from either side of the base 15 a distance suflicient to'provide for a load station 52 and a receiving station 53 disposed on either side of the work position or station 54. I Secured to and upstanding from the laterally extending frame members 50 and 51 are a pair of uprights .55 and 56, respectively. Secured to the top of the uprights and 56 is a plurality of horizontally spaced bar-members '57 which extend transversely of the base 15 above the fixture head 16- A flat elongated supporting plate 58 is secured to the bar members 57. The top rail 48 is fixedly 16 in its ,path of travel on the base l5 a fluid actuator, generally identified by the reference numeral 26, is pro- 27. The extending end 32 0f the piston rod 29 is secured I to a depending bracket 33 which is bolted or otherwise secured to the bottom surface of the head 16. On the opposite endof the base 15 and facing the" 'fixture head 16' there is provided a spindle head 35- which is-fixedly' secured to the base by means of bolts 36. The spindle'head is provided with a quill 37 in which is 'rotatably supported a spindle 38. The spindle38 sup-Q ports a boring bar 39 for rotation with it and; which is; ' in the work station 54, a yieldable backing plate 70 has secured to the spindle in a well known manner. Power for rotating the spindle 38 is derived from an electric motor 42 which is also secured to the base 15 as .by bolts 43, shown in FIG. 2. The electric motor may be of any i conventionaltype-and is operably connected to drive Q. the spindle38 through a conventional belt transmission 44 and a gear. transmission (not shown) disposed'within the spindle head 35 and operably connected to drive the spindle. a r As previously mentioned, the machine tool is operable classified in accordance with thegross weight .of the cars V 'to perform a boring operation on different size railroad 7 car wheels. *In this respect; railroad car wheels are do the ton wheels, Therefore, top'e-rform aboring is provided'with tWo' sets of cutters having different diamwhich will be employedto borei the axial opening in car V .7 70. operation on the diiferent size wheels, the boring bar 39 secured to the bottom surface 59 of the plate 58 above the bottom rail 47. The rails 47 and 48 cooperate to support and guide rollable workpieces, which in this particular instance are railroad car wheels, through the machine; a I 'Another pair of uprights' 62 and 63, are rigidly secured to'the opposite sides ofthe laterallyextending frame members 5i) and 51 respectively, with'each of the uprights 62 and 63 being provided with horizontal fence rails 64 and 65 respectively; Thus, a car wheel supplied toftheloading station 52 from a source (no-t shown) is maintained "in an upright position between the rails 47 and 48 by the fence rail 64 with the flange portion 66 of the car wheel engaging against the guide rails 47 and 48. The fence rail '65 in the station 53 functions in the same manner as does the fence rail 64, .and maintains the car wheel uprightwhen it is rolled or moved from the Work station 54 thereto after a work operation has been completed. g To maintain the car wheel in an, upright position when been provided. Thebacking plate 70 functions, in one respect, in the same manner as do the fence rails 64 and 65 and it,-. also, serves to'ori'ent the car wheel so that its 1, axis will be parallel to the-axis of the boring bar 39. The backing plate 70 comprises an enlarged central car wheel hubengaging portion 71 which is provided with a pair of horizontally extending arms 72 and 73. The arms'72j'and73 extend on either side from the central portion 71 to a point just short of the fence rails 64 and 65',respectively, and are in alignment therewith. Thus, thefence rails 64 and 65'andthe backing plate 70 are, in effect, a f'continuous supportffor maintaining the car wheels in an upright position while in themachine. V Thebackingplate 70 is yieldably supported in position by means of a pair of bar members 7.4'andv 74a; The bar members 74 and74ashownin FIGS. 1, 2 and 4, are horizontally mounted on'eithe rside' of the spindle head 35 i 7/ i and are suppoi ted thereon for axial movement. Since eters; As shown in FIG. 1, the boring bar 39,a't-its ex-', 'both barlm ernbers are su'pported on the spindle head 35 in identical manner; the description willbe confined to the banmernber 74'withflike reference numerals having a '74 and 74a, respectively. letter sufiix given to like parts associated with the bar member 74a. As shown in FIGS. 1 and 2, the bar member 74 is movably supported on the side of the spindle head in two sets of roller members '76 and 77. Each roller set comprises a bracket 78 which is secured to the side of the head 35 as by welding. The brackets '78 have an outwardly extending supporting arm 79 on which are rotatably sup ported in spaced apart upright relationship a pair of spool-shaped rollers 80 and 81. The rollers 80 and 81 of each of the sets 76 and 77 serve to movably support and guide the bar member 74 in a horizontal plane with the axis of the bar member being parallel to the axis of the boring bar 39. The backing plate 70 is secured to the end of the bars 74 and 74a in a manner to move the bars. In order to adjust and limit the forward position of the backing plate 7 t), in relation to a car wheel in the work station 54, the outer ends of the bars 74 and 74a are threaded as at 8'5 and 85a and pass through suitable openings in a pair of stop plates 86 and 86a. The stop plates 86 and 86:: are bolted or otherwise secured to the back face of the spindle head 35 as shown in FIGS. 1 and 2. A pair of adjustable stop nuts 87 and 87a are threadedly engaged on the threaded ends 85 and 85a of the bars, and engage against the stop plates 86 and 86a, respectively, to limit the forward movement of the bars 74 and 74a. The forward limit of movement of the bars 74 and 74a may be adjusted by simply manipulating the nuts 87 and 87a on the threaded ends of the bars until the desired limit of movement has been attained. Since the backing plate is constructed to be yieldable, for a purpose to be more fully described, a weight 90 is operably connected to the bars 74 and 74a. The weight 99 insures that the weight of a car Wheel against the backing plate 70 will not move the backing plate rearwardly and thereby permit the wheel to fall out of its upright position when in the Work station 54. The Weight 90 is housed within the interior of the base 15 below the spindle head 35 and is connected to the bars 74 and 74a by means of a pair of cables 91 and 91a which are attached to the weight 90 by bolts 92 and 92a. The cables 91 and 91a are entrained over a pair of pulleys 93 and 93a which are rotatably mounted on either side of the spindle head 35. The opposite ends of the cables 91 and 91a are fastened to lugs 94 and 94a provided on the bars To permit of free passage of the lugs 94 and 94a through the brackets 78 and 78a whenever the bars are moved rearwardly, the arms 79 and 79a of the rear set of brackets are provided with re cesses 95 and 95a which permit passage of the lugs. While a particular type of weight has been described, any other type of mechanism may be employed for maintaining the bars 74 and 74a and the backing plate 71) inwardly against the weight of the car wheel, as may be desired. Such other apparatus may be a spring, a fluid apparatus, or the like. As previously stated, the car wheels supplied to the loading station 52 are rolled or moved into the work station 54 simultaneously with the movement of a finished car wheel out of the Work station to the receiving station 53. To this end, a transfer mechanism, generally identiiied by the reference numeral 11%) is provided. The transfer mechanism 101), as best shown in FIGS. 4 and 5, comprises a guide plate 161 which is secured to the top surface 1% of the supporting plate 58, as by welding. The guide plate 191 is provided with beveled side portions 103 and 104 which extend through its entire length. A carrier plate 106 is movably supported on the top surface 107 of the guide plate 101. To support and guide the carrier plate 106 in its path of travel on the guide plate 161 three sets of supporting and guiding rollers 108, 108a and 11985 are employed. The roller sets 108a being disposed at one end of the carrier 6 plate 106, the set 1081) being located at the opposite end of the plate, while the set 108 is positioned intermediate the ends of the plate. Each roller set is identical and the description will therefore be directed to the intermediate roller set 168. The roller set 108 comprises a pair of supporting rollers 1119 and 11b rotatably mounted on stub shafts 111 and 112, respectively. The shafts 111 and 112 are threadedly engaged in a horizontal plane into the carreir plate 106. The arrangement is such that the peripheries of the rollers 109 and 111) extend slightly below the bottom surface 113 of the carrier plate 1196 thereby elevating the carrier plate a slight amount from the supporting plate 101 to aiford free rolling travel of the carrier plate on the top surface 107 of the plate 101. To retain and guide the carrier plate 106 over the supporting plate 101 each set of rollers is provided with side rollers 114 and 115. To support the side rollers 114 and 115 in position a pair of brackets 116 and 117, respectively, are provided. The brackets 116 and 117 are fixedly secured to the sides of the carrier plate 1116, as shown in FIG. 5, and are provided with inwardly facing end surfaces 115 and 115 Theadedly engaged into the brackets 116 and 117 and extending outwardly of the surfaces 118 and 119, respectively, are stub shafts 120 and 121 upon which the side rollers 114 and 115 are rotatably mounted. The arrangement is such that the axes of the shafts 12b and 121 are disposed parallel to the bevel surfaces 1&3 and 104, respectively. The peripheries of the side rollers 114 and 115 engage the bevel surfaces 1113 and 194- and roll along these surfaces to retain and guide the carrier plate in position on the supporting plate 1111 as it moves on the supporting rollers 109 and 110. The ends of the guide plate 101 are provided with a pair of end brackets 125 and 126 which are welded or otherwise secured to it. The brackets 125 and 126 each have upstanding end plates 127 and 128 respectively, in which the ends of a relatively long secondary bar 130 are journalled. To rotatably support the secondary bar 130 intermediately of its ends, a plurality of brackets 131, 132, 133, 134, and 136 are provided. The brackets 131 to 136, inclusive, are secured to the side of the carrier plate 106 and move with it, being disposed in spaced apart pairs and function as abutments for enforcing movement in either direction of a plurality of roller arms 137, 138 and 139 mounted on the secondary bar 130. Since the roller arms 137, 138 and 139 are identical, the description of the arm 138 will be given and will also be applicable to the arms 137 and 139. The roller arm 1353, as shown in FIGS. 2, 4 and 5 comprises a body member 141 having a pair of cars or lugs 142 and 143. The lugs 142 and 143 have bored openings 144 which receive the secondary bar 1319. Each of the lugs 142 and 143 is provided with an inwardly extending key 145 which mates in a complementary longitudinally extending keyway 146 provided in the secondary bar 139. Thus, the roller arm 138 is maintained in predetermined position on the secondary bar 130 by the brackets 133 and 134 and is movable in either direction along the bar 131? with the carrier plate 166. The roller arm 138, by virtue of its keyed connection to the secondary bar 139, is also pivotable with a rotational movement of the secondary bar 131). The lower end of the body portion 141 of the arm 138 is provided with a hub 147 having an axial opening which receives a bolt shaft 148. Mounted on the bolt shaft 148 is a car Wheel flange engaging wheel or roller 14?. The wheel or roller 149 is freely supported for rotational movement on the shaft 148, by means of an antifriction bearing 15%) carried by the shaft 143. The entire assembly is secured to the arm 138 by a nut 151 threadedly engaged on the threaded end 152 of the bolt shaft 148. The roller 149 is provided with a radially extending flange 153 with its inner surface 154 being operable to engage against the side face of the flange portion es of the car wheel. Each of the roller arms 137, 138 and 139 are provided '7 with positive stops which insure proper positioning of the roller 149 in relation to the car wheels, when the arms are pivo'tally moved into an engaging position. The positive stops are, also etiective in preventing the" flange 153 of the roller 149, when pivoted into engaging position, from exerting a side force on the, car wheels, , which'force would tend to move the car wheels against the supporting rails 47 and 4-8 thereby preventing free rolling movement of the car wheels between the rails 47 and 4.8. The several positive stops are identical in construction so that in the description itwill only be necessary to refer to the positive stop associated with the arm 138. } As shown in FIGS. 4 and S-the positive stop comprises a threaded stud 157 which is threadedly engaged in a depending portion 158 of the bracket 134. The outwardly extending end of the stud 157, is disposed to engage an inwardly extending boss 159 provided on the body portion 141 of the arm 138. The boss 159 is formed on a lug 160 which is integrally formed on the roller arm .138 and extends laterally therefrom. By adjusting the shown in FIG; 7, are. secured in appropriate spaced rela tionship, on the dog plate 173. In operation, assuming that the roller arms 137, 138 and 139 are in thedisengaged position, the motor '171 'Assuming that a car wheel: is in the load position 52 and also that a car wheel is in the. work position 54, the roller 149a of the'arm 137 will engage the periphery of p the flangeof-the car wheel in the loading station 52 behind the car wheelas shown in FIG. 4. The roller 149 of the arm 138 will engage'the periphery ofthe flange of the car wheel in the] loading station 52 ahead of the car wheel. The roller 149, also, will engage the periphery of the flange of the car wheel in the work station 54 behind the car' wheel. The 'roller' 14% of the arm 139 will engage the periphery-of the flange of the car wheel in the loading station 54 ahead of the car wheel and will likewise engage the flange of the car wheel in the receiving station 53. ' When the roller arms are in position, fluid pressure may 'be supplied to the rod end of the piston (not shown) in thecylinder 165 to effect movement of the carrier plate 106 rightwardly as' viewed in FIG. 4. Since the secondary bar 130 will remain stationary, movement of the may be tightened against the bracketportion'153 to lock. the stud in place. To reciprocate the carrier plate 106 and thereby efiect reciprocation of the roller arms 137, 138 and 139, there is provided a fluid actuator generally identified by the reference numeral 164 The fluid actuator 164 com prises a cylinder 165. having end mounting plates 166 and 167. The cylinder 165 is secured to the top of the carrier plate 106 'by means of threaded studs 168 which are inserted through side flange portions 169 provided on p I 'the end mounting plates 166 and 167 and threadedly engaged into the carrier plate 1%. A piston (notshown) is reciprocally supported in the cylinder 165 and is provided with a piston rod 170. The piston rod 170 extends outwardly of the cylinder 165 and has its outwardly ex tending end secured in the end plate 123. Since the end Y plate 128 is secured to the bracket 126 which in turn is secured to the supporting plate 101, fluid pressure supplied to the cylinder 165 on one side or the other of the piston therein, will cause a movement of the cylinder .andrthe carrier plate 106 to which it is attached. When the" carrier plate 106 is reciprocated, thearrns 137,138 and 139 will move with it by reason of their connection thereto through the associated brackets enforcing sliding movement of the arms on the secondary bar 139. Rotation of the secondary bar 130 to'effect pivotal movement of the roller arms 137, 138 and 139 is achieved The motor 171' manner that the roller arms are pivotally movable be.- carrier plate 106 will cause a like movement of its as 'sociated brackets 131, 133 and 135 which, in turn, will effect movement of the arms 137, 138 and 139, respectively, in the same direction as the carrier plate 106 moves. .Theroller 149a moving with the arm 137 will 'cause a car wheel in the loading station 52 to roll between the supporting rails 4'7. and 48 while the roller 149 on the arm 138 will preventthe car wheel from advancing at rate greater thanthe rate of advancement of the roller 149a thereby controllingthe position of the car wheel relative to the roller 149a. Similarly, the roller 149 of the arm 138 will function to roll the car wheel in the work station 54 out of the work station into the receiving station 53 while theroller149b of the arm 139 V will prevent the car .wheel'from advancing faster than the rate of advancement of the roller 149. The advancement of the car wheels, therefore, isv always controlled "wheel in the work station is under complete control with no possibility of its being inadvertently rolled out of the machine during the advancing movement. Thus, a completely safe and effective mechanism has been provided for advancing a plurality of'relatively largeand heavy rollableworkpieces through a machine tool. The car wheel in the receivingstation 53-is not retarded from rolling forwardly inasmuch as the machining operation on it is completed and it may roll into' a suitable receptable or conveyor for removal from the machine. As previously mentioned, the carl'wheels may be supplied to the loading station 520i the machine tool as by gravity or by any other desired means. To maintain a Z car wheel in the loading station 52 afterit has been suptween adisengaged position, represented by the broken lines in FIG. 5, and a car wheel engaging position, shown a mounting bracket 172, which, in turn, is secured to the end plate 128, is operativewhen actuated in one direction to stop the operation of the'rnotor 171 when the motor has operated to pivot the roller arms into an engaging position; The limit. switch LS2 when actuated in the opposite direction will stop operation of the motor 171 when it has been operated to pivotthe roller arms into in full lines in .FIG. 5. A limit switch LS2 secured to the disengaged position. To actuate the ylimit switch. I LS2 in either direction adog plate 173 is'secure'd to the outer. extending end of the shaft 174, of the motor 17.1. A pair of dogs 175 and 176, which are schematically plied thereto, a gate mechanism, generally identified by the reference numeral 180,.is provided. The gate mechanism 180, as shown inFIGS. 1 and 4, comprises an arm 181 which has one end thereof pivotallyconnected, as at 182, to the upright62 for movement in avertical plane. The arm131 is actuated inthe vertical plane by, means of a fluid actuator 183' The fluid actuator 183 comprises 'the cylinder lsd hasa pistonrod 186 secured to it. The rod 186 extends outwardly of the cylinder 184 and has its free end' pivotally' connected, asat 187, to the opposite end of the arm 181." v I A laterally inwardly extending lug 183 is integrally formed or otherwise secured to the arm 181 and is positioned so as to extend across the path of travel of a car wheel to thereby engage against the flange of the car wheel, when the arm 181 is in its uppermost position. When the piston and cylinder mechanism 183 is actuated to lower the arm 181 the lug 183 thereon is moved below the level of the supporting surface of the guide rail 47 and out of engagement with the car wheel to thereby permit of movement of the wheel. When the piston (not shown) of the piston and cylinder mechanism 183 is actuated in the opposite direction, the arm 181 is moved upwardly to move the lug 188 into a position where it will be engaged by the flange of a car Wheel when a car wheel is supplied to the loading station 52 to limit the forward movement of the car wheel. The arm 181 and the lug 188 thereof, when in the upper position, effectively prevents further rolling advancement of a car wheel. It should be noted that whatever the method of supplying car Wheels to the loading station, whether it be by gravity or by any other means, the rate at which the car wheels are rolled into the station will be at a relatively slow rate, and therefore the car wheel upon contacting the lug 188 will be stopped thereby. The head 16 supports a chuck mechanism, as shown in FIG. 3, and which is generally identified by the reference numeral 192. The chuck mechanism 192 is operable when the head 16 is advanced from the full retracted position, indicated by the broken lines in FIG. 3, to the position that it is shown in, to receive and clamp a car wheel in the work station 54 to the fixture head so that upon further advancement of the head 16 towards the spindle head 35 the car wheel will move with it to be fed to the rotating boring bar 39. To this end, the front face 194 of the end plate 17, as shown in FIGS. 3 and 4 is provided with a plurality of recessed radially extending slideways 195, 1% and 197, which are arranged about a center which is concentric with the axis of the boring bar 39. The slideways 195, 196 and 197 receive and slidably support a plurality of L-shaped slides 198, 199 - and 291, respectively. In FIG. 3 the slideway 195 is shown without its respective L-shaped slide 198 for the purpose of showing the construction of the slideway. The longitudinal edges of the L-shaped slides are recessed to form side flanges 202 and 203 which extend the entire length of and on either side of the portion of the slides within the slideways. To maintain the slides within their respective slideway, a pair of retainer plates 204 and 2il5 are provided for each slide and are secured to the front face 194 of the head 16 as by studs 206. The retainer plates are disposed on either side of the portion of the slide within the slideway and overlap the side flanges 202 and 293 thereof to retain the slides in their respective slideway. The outwardly extending leg portions 207 of each of the L- shaped slides 198, 199 and 291 are provided with jaws 208 which are formed so as to fit against the contour of the flange and tire of the car wheel. The jaws are secured to the portions 297 by cap screws 299. As shown in FIG. 4, the slideways are formed in the front face 17 of the head 16 in a manner that the slide ways 195 and 197 are disposed equiangularly on either side of a vertical center line through which the axes of the boring bar 39 and the chuck mechanism 192 pass. The sideway 196 is disposed so that its axis coincides with the vertical center line. The arrangement is such that when the L-shaped slides are actuated in a clamping action, the slides 198 and 201 in the slideways 195 and 197 respectively, will cradle the car wheel to prevent any lateral movement of the car wheel and will slightly lift the car wheel off of the rail 47 to center the car wheel in relation to the axis of the boring bar 39. The slide 199 will maintain the car wheel in axial alignment with the axis of the boring bar 39. In order that the slide 199 may pass forwardly past the top guide rail 48 when the head is moved toward the spindle head 35, the rail is provided with an opening 211). The opening 210 is of sufficient dimension, both in height and width, so that the slide 199 will freely pass through it. To actuate the slides 11%, 199 and 201 in a clamping or releasing movement a novel actuating mechanism 215 is provided. As shown in FIGS. 3 and 6, the actuating mechanism 215 is contained within the head 16 and comprises a plurality of arms 216, 216:: and MM. The arms are identical in construction and arrangement, therefore a description of the arm 216 will apply to all of the arms. The arm 216 is pivotally mounted on a shaft 217 which is mounted in an opening 218 provided in the face plate 17 of the head 16. The opening 218 communicates with the interior of the head 16, extends through the end plate 17, and opens into the slideway 196 provided in the front face 194. Similar openings for the slideways and 197 are provided, and in FIG. 4 the slide for the slideway 195 has been removed and the opening is there identified by the reference numeral 213a. The outwardly extending end of the arm 216 is provided with a ball end 219 which extends into a recess 2213 provided in the back face of the slide 199. The arrangement is such that pivotal movement of the arm 216 about the shaft 217 will effect movement of the slide 199 in the slideway 196. The inner or longer end 221 of the arm 216 is provided with an inwardly facing shoe 222 which is adapted to ride upon a cam surface 223 of a cam sleeve 224. The cam sleeve 224 serves to actuate the arms 216, 216a and 216k and is slidably mounted on a tubular support 225. The support 225 is mounted in a central axial opening 226 provided in the end or face plate 17 of the head 16. The opening 226 is disposed so that its axis coincides with the axis of the boring bar 39. To prevent rotation of the cam sleeve 224 on the tubular support 225 and thereby prevent misalignment of the cam surfaces relative to the associated arms, the cam sleeve 22 i is provided with a longitudinal keyway 227 which slidably receives a key 228 carried by the tubular support 225. Likewise, the tubular support 225 is prevented from rotating within the opening 226 by means of a locking rod or shaft 235, shown in FIG. 4. The rod 235 is inserted in a bore 236 provided in the end plate 17 which extends angularly upwards to communicate with a suitable recess provided in the tubular support 225. The locking rod 235 is maintained in place within the bore 236 by a screw plug 238. The locking rod 235 not only serves to prevent rotation of the tubular member 225 within the opening 226 but, also, insures that the tubular member will not move axially. The end 221 of the arm 216 is urged radially inwardly to maintain it in engagement with its respective cam surface to thereby insure positive positioning of the slide when in an unclamped position. To this end, a compression spring 238 is mounted in a bracket 231 which is bolted to the end plate 17, as shown in FlG. 3. A stud 22? is threadediy engaged in a boss 232, provided on an extending leg 233 of the bracket 231, and abuts the end of the spring housed within the boss 232. The opposite end of the spring 239 is seated in a recess pro vided in the top surface of the arm 215. By adjusting the stud 229 inwardly the force that the spring 230 will exert upon the end 221 of the arm 216 may be increased, or by adjusting the stud 22% outwardly the force may be decreased. A jam nut 234 threadedly engaged on the stud 229 serves to lock the stud in an adjusted position. A resilient arrangement is also provided for maintaining the arms 216a and 2116b in engagement with the cam operating member 224. The structure provided for resiliently urging the ends of the arms 216a and 21Gb are identical and therefore a description of the arrangement for the arm 216a Will be given, which description will also apply to the arrangement for thearm 215b. As shown in FIG. 6, an upwardly sloping bore 237is pro- .vided in the wall 18 within which a tube 267 is press fitted and extendsinwardly toward the ends of the arm 216a. A compression spring 243' is inserted within the, tube 267 and has its inner end seated in a recess 268 in the end of the arm21da. A rod 239 is movably contained within the tube 257 in abutting engagement with the outer end of the spring 243 within the tube267. The rod 239 is of sufiiicent length so that when it is fully inserted within the tube 267 it will act to preload the spring 243 to a degree that the spring 243 will urge the end of the arm 216a radially inwardly so that its shoe 222!) will be maintained in constant engagementwith a cam surface 240 provided on the cam sleeve 224. The rod 239 is maintained within the tube 267 by means of a retaining washer 241 which is maintained in place .by a screw 244 threaded into the surface of a boss 242 provided on the wall 18. As previously mentioned, the end of the arm 2161b is similarly maintained in engagement with its associated cam surface 256' on the'cam sleeve 224, as is the arm 216a. To actuate the arms 216, 216a and 216b a fluid reciprocating motor 245 is provided and is carried by the head 16. To this end, as shown in FIGS 3 and 6, a mounting plate 246 is supported on carrier lugs or shelves 247 and 248 integrally formed on the inner sur- -faces of the walls 18 and 19, respectively. The mounting plate 246 is secured on the lugs 247 and 248 by bolts 249 which are inserted through suitable openings provided in the sides of the walls 18 and 19 into threaded engagement with the sides of the plate 246. The reciproeating motor 245 is mounted on the plate 24-6 and includes a reciprocating rod 250 which extends from the right'end of the motor 245 as viewed in FIG. '3 and is disposed so that its axis is concentric with the common axis about which the slides 198, 199 and 2131 are radially movable. The outer extending end of the rod 250 is threaded as at 251 and is threadedly engaged in a manifold plate 252. The manifold plate 252 is provided with an annular flange 253 which seats against an inwardly extending'antnular flange 254- provided on the end of'the cam sleeve 252 as bybolts 261'thereby effectively locking both the manifold plate 252 and the plate 258 on either side of the annular flange 254 in a manner to effect ahydrualic seal and form a chamber therebetween. A threaded opening 265 provided in the plate 25?- receives a. threaded end of'a coolant supply pipe 266 which is connected to a flexible conduit (not shown); which, in turn, is ccnnected to the coolant supply source (notshown). The manifold plate 252' is also provided with ath'readed t opening 2'70 which receives the threaded end of a cool ant discharge pipe 271. The chamber 262 formed by the recess 255 and the plate 258 serves as a connect 7 ing passage between the two; pipes 266 and 271. A battle plate or'sealing plate 272 is mounted around the dischargepipe 271, being secured to theend of the opening'278 which, as shown in FIG. 3, is positioned at the bottom of the support and which is in communication with an opening 279 provided in the end plate 17 of the head 16. The openings 278 and 279 'serves as a chip passage for the material removed by the boring bar when operating upon the car wheel. In operation, when the head 16 is advanced from its fully retracted position, indicated by the broken linesin FIG. 3 to the position adjacent the car wheel in the work station 54, .the reciprocating motor 24-5 is actuated to effect movement of the rod 259 leftwardly, as viewed in FIG. 3. Movement of the rod 250 leftwardly will effect leftward movement of the cam Sleeve 224. Upon leftward movement of the cam sleeve 224 the ends of the arms 216, 216a and 21617 riding upon their respective cam surfaces 223, 240 and 244 will be moved radially outwardly pivoting the arms on their respective pivot shafts 217, 217a and 2171). The outer ends of the arms 2116,2164: and 21Gb connected to their associated slides will move the slides radially inwardly to force the jaws 253 into engagement with the periphery of the car wheel. The bottom slides 193 and 261 in moving inwardly will cradle the car wheel between them and lift and center the car wheel so that its axis will coincide with the axis of the boring bar 39. The slide 199 will move inwardly down on the car wheel and the three slides will thereupon coact to securely hold the car wheel in an axial aligned position. I The head 16, upon being moved to the car wheel engaging position, will act to orientate the car wheel by moving it slightly outwardly again the car wheel hub engaging portion 71 of the backing plate 70. Since the backing plate is maintained in its forward position by the associated Weight 90, the car wheel will be urged against vertical locating pads 280'provided on each of they slides 198, 199 and 201. This action insures that the car wheel will be in a" vertical position so that the slides 198, 199 and 201' of the chuck mechanism 192 will position and hold the car wheel in true axial alignment with the axis of the boring bar 39. Thus, there is no possibility of the car wheel'being misaligned in respect to the boring bar 39 as by being canted when the slides engage the periphery of the car wheel. In the unclamping action, the'reciprocating motor 245 is actuated to effect movement of'the rod 250 outwardly or rightwardly, as viewed in FIG. 3. Rightward movement of the rod; 250 will effect movement of the cam sleevef224 to the. right to release the pressure exerted by the c'am'surfaces on the ends of the associated'arrns so that thelcam .contactihgends of the arms under the pressure of their cooperating springs will be urged inwardly to effect movement. of the slides 19%, 199 and "291 radially outwardly. The bottom slides 198 and 261, in which the car Wheel is cradled, upon being moved in a release direction, will lower the car wheel to the supporting rail 4750 that the car wheel is again in position to'be advanced or rolled into the receiving station 53. The: action of the, clamp-mechanism 215, and movements ofthec'lamp head 16 and transfer mechanism 160 aswell as rotation of the secondary bar member'13t) are the result of hydraulic pressure being applied to the various "hydraulic cylinders which actuate the movements. sequential operation of thevarious electromagnetically tubular support225 and serves'to prevent coolant dise t trieal circuit used in conjunction with the limit switches r and electromagnetically operated valves has not been charge from the pipe 271 from flowing'rearwardly toavard the manifold plate 252. The tubular support 225. ' recess 275 serves to "receive the extending end of the i boring bar 39 and theicutters 45 thereon-when the chuck The various limit switches employed to effect operated valves employed in the hydraulic circuit are diagrammatically shown inFIG. 7. However/the elecshowmas the circuit'as' such, forms'no part of the present invention, The oil pressure in 'the hydraulic circuit is -stantlydri ven by an electric motor (not shown). head 16 is actuated to advance a car wheel tothe cutters t t Itwilhbeassumed-that the machine tool is initially 'conditionedso'that tthetransfer mechanism 109 is fully retracted leftwardly, asshown in FIG. 4, and theroller arms 137, 138 and 139 are raised to a disengaged position, with the chuck head 16 fully retracted and the gate mechanism 180 in a raised or workpiece stop position, as shown in FIG. 4, and with a finished workpiece W1 in the work station 54. A workpiece W2, which in this particular instance is assumed to be a 41) ton railroad car wheel, is supplied to the loading station 52, as by gravity. The car Wheel or workpiece W2, upon rolling into the loading station 52 will depress a limit switch LS1, shown in FIGS. 1 and 4, as secured to the outrider 50 in position so that a plunger 292 thereof will be depressed by the car wheel W2 when in the loading station 52. The limit switch LS1, when depressed, closed an electrical circuit to energize a solenoid 293 of a hydraulic circuit unloading valve 294 to move a spring centered plunger 295 in the valve leftwardly to connect a pressure inlet port 296 thereof to a port 297 via a cannelure 298 provided in the plunger 295. Thereupon, oil is drawn from an oil reservoir 390 through an oil filter 301 and intake pipes 392, 393 and 304 into the pumps 290 and 291 from where the fluid is pumped into the circuit under pressure. The fluid flows from the pump 291 into an oil line 305 and through a connected check valve 386 into a pressure supply line 307 into the port 296 of the valve 294. From the inlet port 296 fluid under pressure will flow through the valve 294 via the cannelure 298 and out through the port 297 into an oil line 388 and thence into a chamber 309 of the fluid actuator 164 ofthe transfer mechanism 160 on the rod side of the piston thereof to insure that the transfer mechanism is in a fully retracted position. A chamber 310 in the actuator 164 on the head side of the piston thereof is vented to the reservoir 301) via a line 311 connected to a port 312 provided in the valve 294. With the plunger 295 of the valve 294 positioned to the left as previously stated, the port 312 is connected to a fluid outlet port 313 in the valve 294 via a cannelure 314 i nthe plunger 295. The port 313 is connected to the reservoir 380 by an oil line 315, a check valve 316 and an oil return line 317. The limit switch LS1, upon being depressed, is also electrically connected to energize a solenoid 320 of a solenoid valve 321. The solenoid 320, upon being energized, operates to position a plunger 322 therein leftwardly, thereby connecting an inlet port 323 to a port 324 of the valve via a cannelure 325 provided in the plunger and also connects an exhaust port 326 with a port 327 via another cannelure 328 in the plunger 322. Thereupon, oil in the pressure supply line 367 will flow into a branch line 329 and through a check valve 330 and a line 331 into the inlet port 323 of the valve 321. Oil under pressure will continue to flow through the valve 321 via the cannelure 325 and out through the port 324 into a line 332 connected to one side of the fluid motor 171 to rotate the arms 137, 138 and 139 into workpiece engagement. Simultaneously with the operation of the pump 291 the pump 290 is operating to pump fluid under pressure into a supply line 335 and is directed thereby through a check valve 336 into an oil line 337 and flows therein to a solenoid valve 338. A plunger 339 is spring centered within the valve 338 and in this position serves to block fluid from passing through the valve. Thus the head 16 is hydraulically locked in a fully retracted position. A branch oil line 340 connected to the supply line 335 and to an inlet port 341 of a solenoid valve 342 receives fluid from the supply line 335. Fluid flowing to the inlet port 341 of the valve 342 passes through the valve via a cannelure 343 provided in a plunger 344 within the valve and flows out through a port 345 into an oil line 346. The line 346 is connected to a chamber 347 on the rod end of the piston therein of the chuck actuator 245. Since the chuck mechanism 192 is unclamped, the fluid pressure flowing from the line 346 into the chamber 347 will serve to maintain the chuck mechanism unclamped. Excess fluid in the supply line 335 will flow into another branch line 348 connected to a port 349 of a blocking valve 350. Fluid entering the port 349 of the valve 350 will pass through a passage 351 provided in a movable plunger 352 within the valve and flow out through a port 353. As shown in FIG. 7, the passage 351 is normally maintained in alignment with the ports 349 and 353 through the action of a spring 354 contained within the valve and acting upon the plunger 352 to position the plunger so as to maintain the passage 351 in alignment with the ports 349 and 353. Fluid flowing through the valve 350 will enter an oil line 355, which is connected into the supply line 307, and combine with the fluid supplied by the pump 291. The combined fluid output will actuate the motor 171 in a counterclockwise direction thereby rotating the secondary bar to pivot the arms 137, 138 and 139 into workpiece engagement. The dog plate 173 connected to the fluid motor 171 will rotate in a counterclockwise direction and the dog 175 thereon will actuate the limit switch LS2 in a clockwise direction, as viewed in FIG. 7, at the time that the arms 137, 138 and 139 engage the workpieces. The limit switch LS2, upon being actuated in a clockwise direction, will interrupt the electrical circuit to the solenoid 320 of the valve 321 and to the solenoid 293 of the unloading valve 294. When the solenoid 293 of the valve 294 is de-energized the plunger 295 thereof will be resiliently centered, to connect ports 296 and 297 together via a passage 36!), and ports 312 and 313 together, via a passage 361 provided in the plunger 295. The passages 360 and 361 are interconnected by a passage 362 which functions to unload the hydraulic circuit, returning fluid supplied by the pumps 290 and 291 to the reservoir 300. To start a machining cycle for a 40 ton car wheel, the operator actuates a cycle start switch 363 disposed in a control panel 364. The control panel 364 is mounted on the side of the spindle head 35 in position to afford an operator, stationed at the panel, a clear view of the operation of the machine tool. The cycle start switch 363, when depressed, establishes an electrical circuit to the .solenoid 293 of the unloading valve 294 to energize the solenoid and to effect movement of the plunger 295 leftwardly to pressurize the system, as previously described. The cycle start switch when depressed, also, establishes an electrical circuit to actuate a solenoid valve 365 by energizing a solenoid 366 to move a plunger 367 rightwardly and thereby connect an inlet port 368 with a port 369 by means of a passage 370 provided in the plunger. Movement of the plunger 367 to a rightward position will also connect a port 371 and a port 372 together through another passage 373 provided in the plunger 367. Thereupon, the combined fluid from the pumps 290 and 291, flowing in the fluid supply line 307 will flow into a branch line 376 and enter the port 368 of the valve 365 and pass therethrough via the now aligned connecting passage 370 in the plunger 367 and out through the port 369 to the fluid actuator 183 of the gate mechanism via a line 377. Oil flowing in the line 377 is directed into a chamber 378 at the rod side of the piston of the actuator 183 to effect a lowering of the gate mechanism out of its car wheel stop position to free the car wheel for an advancing movement. When the actuator 183 operates to lower the gate 180, fluid in a chamber 387 on the head side of the piston of the actuator 183 is forced out into a line 388 and flows through the solenoid valve 365 via the port 372, the passage 373 and the port 371 to return to the reservoir 300 via a return line 389 and the line 408. When the gate mechanism is lowered, a limit switch LS9, shown in FIG. 4 as secured to the upright 62 adjacent the lower rail 47, is contacted by the arm 181 to interrupt the electrical circuit to the solenoid 293 of the valve 294 and to the solenoid 366 of the valve 365 to a '15 de-energize the solenoids. Thereupon, theplunger 295 of the valve 294 will be spring returned to a centered position, while the plunger 367 of the valve 365 will remain as presently positioned but will be conditioned for subsequent leftward movement upon energization of a solenoid 380 connected thereto. 1 a The,depressed'limit'switch LS9 also establishes .an electrical circuit to a solenoid 382 of the valve 294 and to the solenoid 320 of the valve'321 to energize the solenoids. Since the plunger 322 of thevalve -321 is positioned in a leftward position through a previous energization of the solenoid 320 the present re-energization of the solenoid 320 serves to insure positive retention of the plunger 322 of the valve in the leftward'position so that fluid pressure will be .supplied to the motor 171 to maintain the arms 137, 138 and 139 in workpiece engagement. Energization of the solenoid 382 of the valve 294 will effect a movement of the plunger 295 therein to a rightward position whereby ports 296 and 312. are connected together through a passage 383 and portsl313 and 297 are connected together through a passage 384 provided in the plunger 295. Fluid pressure in the line 307 will now enter port 296 of the valve 294 and by means of the connecting passage 383 will pass through'the valve and flow out through the port 312 into the oil line 311. Fluid will then flow into the chamber 310 of the transfer mechanism actuator 164 to move it axially effecting a' rolling advancement of the car wheels to their succeeding stations, as previously described. At the end of the advancement movement, a limit switch LS4 is actuated by means of a rod 385, shown in FIG. 4 as being mounted on the bracket 136- The -the sideof the frame 15 in position to be engaged by the dog 410. Actuation of thelirnit switch LS6 functions to' effect a stoppage of the advancement of the chuck head 16., In this respect,.the limit switch LS6, when actuated, interrupts the electrical circuit to the solenoid 386 of the valve' 338 thereby de-energizing the solenoid to permit the plunger 339 thereof to be biased to a centered position thereby blocking the flow of fluid'under pressure to the actuator 26. 1 The limit switch LS6, when actuated, will'also establish an electrical circuit for energizing a solenoid411 to effect movement of the plunger 344 of the valve 342 to a right- Ward position, as shown in FIG. 7. With the plunger in the rightward position, fluid pressure in the line 335 will flow therefrom to the inlet port 341 of the valve 342 via a line 340. Fluid will flow through the valve via the cannelure 343 in the plunger 344 thereof and flow out through the port 345 to the chamber- 347 of the chuck actuator 245 via the line 346. Fluid pressure flowing to the chamber 347 'ofthe actuator 245 will effect a movement of the slides 198, 199 and 201 in a clamping action limit switch LS4 is shown as being secured to thetop 392 provided in the plunger 339. 7 Also, a port 393 and a port 394 of the valve 338 are connected together by means of another cannelure 395. Upon the positioning of the plunger 339, of the valve 338 into the leftward position, fluid supplied by the pump 290 to the port 396 will flow through the valve 338 via'the for clamping the car wheel to the chuck head 16 as described. Fluid inpa chamber 413 of the actuator 245 on the head side of the piston therein will be forced'out; into a line 414 and flow through'the solenoid valve 342 via a port 415, a cannelure 416 in the plunger 344, and a port 417 to return to the reservoir 300 via a return line 418 and the line 408. When the car wheel is fully clamped in the chuck 192, the pressure in the line 346 Will build up whereupon a pressure switch 420, connected into the line 346,'will be actuated. When the pressure switch 420 is actuated the condition of the valves 350, 338, 321 and 365 will be eflected simultaneously. Inthis respect, a solenoid 421 of the valve 350 will be energized to move the plunger 352 therein and move the passage 351 out of alignment with the ports 349 and 353 thereby blocking the flow of fluid through the valve. The closing of the valve 350 Will port 390, the cannelure 392 and the port. 391, into aconnected oil line 396 to a chamber 397 of the head. actuator 26. This demand on the pump 290 Will effect .a drop in pressure in the oil line 355. Since the demand. on the pump 291 has been met, the pump would normally and a reservoir return line 401. However, due to. the drop inpressure in the line 355, excess fluid from the pump 291 will flow from..the line 307 into the line 355 from where itwill pass through the open'valve 350 1nt0 the line 348 to the line 335 to combine with the oil from the pump 290. The combined oil from the two pumps 290 and 291 will then be delivered under pressure. to the chamber 397 of the actuator26, as previously described, to advance the chuck head 16 at a rapid rate. unload through a line 398,'a relief valve 399, a line 400, divide the hydraulic circuit into two separate systems, the one having the pump 290 to serve the head actuators 26 and the clamp actuator 245; and the otherin which the pump 291 serves the gate actuator 183, the transfer actuator '164 and the fluid motor 171. In this manner, the speed advantage of two volume combination pump may be uitlized when advancing orretracting the head 16 at a rapid rate and the advantage of the single pump systems in maintaining constant pressure may be employed When advancing at a feed rate. Thus, when an actuator served by the pump 291-.is' moved, there will be no drop in pressure'in thefeed actuator '26 or the clamp actuator 245 since these have now been divided into separate systems. In addition, the solenoid 386 of the .valve 338 will be again energized'to. direct, fluid pressure from the pump 290' to the chamber 3970f the head actuator 26 to ad Vance the head. 'As the head 16 starts to advance, a dog 422 'adjustably secured to the side of the head 16, as shown in FIG; 3, engages a plunger 423 of the valve 405 to effect a blocking of an opening within the valve. Thus, ' theflow of exhaust fluid from the chamber 402 of the actuator 26 through'the valve 405 is blocked and the fluid exhaust willv be forced back to the reservoir over a flow control valve 407 connected between the line 403 and 406. Fluid-in aichamber 402on the rod side of the p'iston of the actuator 26' will be forced .out of the chamber into. a line 403 and will flow through the line into a line 404. From the line 404 fluid will flow through a'valve 405 into a line 406 and pass through the solenoid valve 338 via. the port 394, the cannelure .395 in the plunger '339, and I a of a cannelure 424'prov1ded 1n the plunger. Thereupon, the port 393 to returnto' the'reservoir 300 via a return line 408. I 4 When the chuck head 16 has bee'n moved to 'a'position I 5 'tr'ol valve 407. Thereafter theadvancement of the head 16 will be at a feed rate as determined by the setting'o'f the flow con- The pressure switch 420 will also' energizethe solenoid 330 ofthe valve 365 to move the plunger thereof to a leftward positionfl n the leftward position the inlet port 368 and the port 372 areconnected together by means 7 fluid pressure in the line1376 Will flow throughthe valve adjacent the car. Wheel in the work station 54, a dog 4 10 adjustably secured'on'the side'of the head 16,-as shown in FIG. 3, will actuate a limit switch LS6 mounted on '365 via, the port.368, the' cannelure .424 and the'port 372 andbe directed to the chamber 387 on the head side of the piston of thegate actuator-183 by means of the oil line 388. Fluid pressure in the chamber 387 of the gate actuator 183 will move the gate mechanism 180 into a blocking position so that the loading station 52 is now conditioned to receive a new workpiece or car wheel. As the actuator 183 operates to position the gate mechanism into a blocking position, fluid in the chamber 378 is forced out of the chamber intothe line 377 and will flow through the valve 365 via the port 369, a cannelure 425 provided in the plunger 367 of the valve 365 and the port 371 to return to the reservoir 300 via the lines 389 and 408. As the head 16 is advanced to feed the car wheel to the tool 39 in a work operation, the transfer mechanism 100 will be reconditioned or reset for another cycle of operation. The resetting of the transfer mechanism 100, during the machining or work operation will effect a reduction in the overall time that a complete cycle of operation takes, thereby the production rate of the machine tool is materially increased. Thus, simultaneously with the energization of the solenoids 421, 386 and 380, the pressure switch 420 will also establish an electrical circuit to a solenoid 430 of the valve 321 to energize the solenoid and move the plunger 322 thereof to a rightward position. Thereupon fluid pressure in the line 329 will flow through the valve via the inlet port 323, a passage 431 in the plunger 322 of the valve and the port 327 into an oil line 432 connected to the opposite side of the fluid motor 171. Fluid pressure supplied to the opposite side of the motor 171 will effect a clockwise movement of the motor to rotate the secondary bar 130 and pivot the arms 137, 138 and 139 out of engagement with the car wheels and into a raised position. At this time fluid exhausting from the motor 171 will flow into the line 332 and enter the valve 321 through the port 324. The exhaust fluid will pass through the valve via another passage 433 provided in the plunger 322 of the valve and out through the port 326 and return to the reservoir 300 via the return line 317. When the motor 171 has operated to raise the arms 137, 138 and 139, the dog 176 on the dog plate 173 will contact the limit switch LS2 and actuate it in a counterclockwise direction. The limit switch when actuated in the counterclockwise direction functions to interrupt the electrical circuit to the solenoid 382 of the valve 294 to de-energize the solenoid. The solenoid 382 having been previously energized when the gate mechanism 180 was lowered and depressed the limit switch LS9. When the solenoid 382 is de-energized the plunger 295 of the valve is spring returned to its center position. Simultaneously with the de-energization of the solenoid 382 the limit switch LS2 also functions to establish an electrical circuit to the solenoid 293 of the valve 294 to energize the solenoid and move the plunger 295 into a leftward position. With the plunger 295 of the valve 294 in a leftward position, fluid pressure from the pressure supply line 307 will flow through the valve via the inlet port 296, the cannelure 298 and the port 297. From the port 297 fluid pressure is directed into the chamber 309 of the transfer actuator 164 by the oil line 308. Fluid pressure supplied to the chamber 309 will effect a retraction of the transfer mechanism to its start position, thereby releasing the limit switch LS4 which will spring return to its normal condition. The transfer mechanism is now reset for another cycle of operation. As the actuator 164 operates to retract the transfer mechanism 100, fluid in the chamber 310 will be exhausted therefrom into the line 311. From the line 311 the exhaust fluid will enter the valve through the port 312 and be directed through the valve by the cannelure 314 and will flow out through the port 313. From the port 313 the exhaust fluid will flow into the line 315 and return to the reservoir 300 via the check valve 316 and the return line 317. When the transfer mechanism has been fully retracted, a limit switch LS3, shown in FIG. 4 as secured to the end plate 127, is actuated into an open condition by a rod 435 carried in the movable plate 106. The limit switch LS3 is of the type that is normally closed and maintained in the closed position by spring pressure. The limit switch LS3, upon being actuated to an open condition, interrupts the electrical circuits to the solenoid 430 of the valve 321, the solenoid 380 of the valve 365 and to the solenoid 293 of the valve 294 to thereby unload the pump 291 through the valve 294, as previously described, and, also, to condition the valves 294, 365 and 321 for a subsequent cycle of operation. During the time that the transfer mechanism is being retracted and the valves of the system served by the pump 291 are being reconditioned for a subsequent cycle of operation, the pump 290 is continuing to supply fluid pressure to the head actuator 26 to feed the car wheel to the boring bar 39 in a work operation. This action will continue until the dog 436, shown in FIG. 3 as being adjustably mounted on the side of the head 26, contacts a limit switch LS7. The limit switch LS7 is mounted on the base 15 in position to be engaged by its associated dog 436 upon completion of the machining operation. When the limit switch LS7 is actuated, the electrical circuit to the solenoid 421 of the blocking valve 350 is interrupted, thereby de-energizing the solenoid to permit the return of the plunger 352 therein to its normal open condition. With the valve 350 in its normally open condition the hydraulic systems served by the pumps 290 and 291 are again interconnected through the line 348, the valve 350 and the line 355, as previously described. Simultaneously with the de-energization of the solenoid 421, the limit switch LS7 functions to establish an electrical circuit to the solenoid 293 of the valve 294 to energize the solenoid to once again move the plunger 295 thereof to a leftward position to pressurize the system, as previously described. Also, the limit switch LS7 interrupts the electrical circuit to the solenoid 386 of the valve 338 to de-energize the solenoid and permit the plunger 339 thereof to be spring returned to its normal or centered position. Simultaneously with the de-energization of the solenoid 386 of the valve 338, an electrical circuit is established to a solenoid 437 of the valve 338 to energize the solenoid and effect a movement of the plunger 339 of the valve to a rightward position. The plunger 339, when in a rightward position, functions to connect the pressure line 337 to the line 406 via the inlet port 390, a passage 438 in the plunger 339 and the port 394. Thereupon, the combined fluid pressure in the line 337 will flow through the valve 338 via the port 390, the passage 438 and the port 394 into the line 406. Since the valve 405 has been previously actuated closed upon the advancement of the head 16, the fluid pressure in the line 406 will build up and flow through a check valve 439 into the line 403 and be directed thereby into the chamber 402 of the actuator 26 to retract the head 16. The head 16 will be retracted at a rapid rate until the car wheel, held in the chuck mechanism 100, is positioned over the guide rail 47, as shown in FIG. 3. When the head 16 has been retracted to this position a dog 440 adjustably mounted on the side of the head 16, as shown in FIG. 3, actuates a limit switch L810. The limit switch LS10 is carried on the side of the base 15 in position to be engaged by the dog 440. The limit switch L810, upon being actuated, functions to interrupt the electrical circuit to the solenoid 437 of the valve 338, de-energizing the solenoid to permit the return of the plunger 339 to its center block position, thereby stopping retraction of the head 16. The limit switch LS10 also functions to interrupt the electrical circuit to the solenoid 411 of the chuck valve 342 to de-energize it and, simultaneously, establish an electrical circuit to a solenoid 442 of the same chuck valve 342 to energize it and effect a movement of the plunger 344 thereof into a leftward position. Thereupon fluid pressure in the line 340 will flow through the valve 342 via the inlet port 341, a chamber 413 of the chuck actuator 245 to effect un- V clamping of the-car wheel and replacement of the car wheel on the rail 47. During [the unclarnping action fluid in the chamber 347 of the actuator 245 will exhaust into the line 346 and flow through the valve 342 via the port 345, a passage 444 in the plunger 344', and the port 417 to return to the reservoir 300 via the lines 418 and 408. The pressure drop in'the line 346 will effect a resetting of the pressure switch. 420 for subsequent operation. When the chuck mechanism 192 is fully unclamped, the pressure in the line 414 will'built up and'actuate a pressure switch 455, connected into the line 414. The pressure switch 455, upon being actuated,.functions to interrupt the electrical circuit to the solenoid 442. of the chuck valve 342 to de-energize the solenoid'and' condition the valve for another cycle of operation. The pres sure switch will again establishan electrical circuit to the solenoid 437 of the valve 338 to energize the solenoid to reposition the plunger 339 into a rightward position thereby directing fluid pressure to the chamber 402 of the head actuator 26 to fully retract the head to its initial position, indicated by the broken lines in FIG. 3. As the head 16 is moved to a full retracted position, a dog 447, 'shown'in FIG. 3 as being adjustably mounted on the side of the head 16, engages the plunger 423. of the valve 405 to lift the plunger thereby opening the valve to recondition it for the next cycle of operation and to by-pass the hydraulic pressure being directed to the actuator 26 for retracting the head 16. I When the head l6vhas been fully retracted, a dog 448 adjustably secured to the side of the head '16, as shown in FIG. 3, actuates a limit switch LS5. The limit switch "LS is mounted on the frame 15in position to be engaged by the dog 448. The limit switch LS5, when actuated, with interrupt the electrical circuits to the solenoids 293 and 437 of the valves 294 and 338, respec' tively. The solenoid 437, upon being tie-energized, will permit the return of the plunger 339 of the valve to its central blocking position and will be conditioned for the next cycle gf operation. De-energization of the solenoid 293 will permit the plunger 295 of the valve 294 to return to its central position, thereby unloading 'both pumps through the passage 362 as previously described. As previously stated, the machine tool is designedto ac-' commodate different sizercar wheels and-the operation has been described as including the actuation of. a cycle start switch 363 to initiate an automatic cycle of operation in conjunctionwith a 40 ton car wheel. However, if the car wheel to be operated upon is of a larger size, necessitationg the feeding of the car wheel to the cutters 46 of V 2g s 7 having a hollow base 480 on one end of which is supported a spindle head 481 for horizontal movement, The top surface 482 of the base 480 is provided with a pair of guideways 483, one ofwhich is shown, in guiding engagement with complementary guidewaysformed in the spindle head 481 in a well known'manner. The spindle head 431 is provided with a horizontally disposed rotatable spindle 484 in which a boring bar 485 is secured for rotation therewith, The boring bar 485'is similar to the boring bar39, shown in FIG. 1. 'T he boring bar'485 is provided with a first or forwardly located set of cutters 486 and a second or rearwardly set of cutters487. The sets of cutters are arranged for performing a boring operation of different diameters, thus, constituting operational zones for performing selective operation on railroad car wheels of different rate load sizes in the manner previously described for the construction illustrated in FIG. 1. Power for driving the spindle 484 is derived from an electric motor 488 secured to the spindle head 481 and operably connected to drive the spindle 484through a gear transmission (not shown) operably contained within the spindle head 481 in a well known manner. 7 The spindle head 481 is moved along the guideways 483 by means of a fluid motor 490 comprising a cylinder 491 which is secured to a horizontal platform 492 integrally formed within the'hollow base 480. 'A piston (not shown) .is reciprocally supported within the cylinder 491 and is ture head 497 comprises a hollow frame493 the front face of which is provided with transverse recess or passage 501 which serves to receive the forward end of the boring bar 485 whenever the spindle head 481- is advanced to employ the rearwardly set of cutters 487 in a work operation. The recess 501 also accommodates the transfer mechanism 100 which operatesto roll car wheels in a controlled rolling movement, into and out of the work position, as previously described. Extending transversely of the base 480' and located between the spindle head 481 and the fixture head 497 isa I surfaces of laterally extending side members 503. The the boring bar. 39, the operator would actuate another 4 cycle start switch 455 in the control panel 364 which simply renders the limit switch LS7 inoperative upon being contacted by the dog 436. The head'16 carrying the car wheel would then be advanced until the cutters 46 completed a work operation on the wheel, at which time a dog side members 503 are table like structures which are secured to the sides of the base 480 and extend outwardly thereof from either side. Upstanding from the side members 503 are a plurality of supports 504, one of which is shown in-FIG. 8. Each-ofthe upstanding support members 504 are provided with an extending arm 505 to the under sideof which is'secured a pair of depending brackets 506 and 507. A fence rail 510 is secured to each bracket 506 and extends from the outermost end of each of the side members to a point shortof a vertical line which machine to the center thereof wherein a gap or space is provided. Extending outwardly from the face of the fix- LSS, when actuated, is arranged to function exactly as does the limit switch LS7. It is therefore deemed unneces saryto describe the functions occurring upon actuation of the limit switch LS8, as the description given in conjunction'withfthe limit switch LS7 will apply. The control panel 364 accommodates various other elec- 8, 9 and 10, there is provided a horizontal boring machine ture head 497 into the space provided in the fence rail 510 and, secured to the face of the fixture head is a car wheel locating pad511, shown in FIGS. '8, 9 and 10, which is employed to orientate a car wheel in a vertical plane. Similarly, another fence 'rail512 is secured to the brackets 507 so that it is spaced from the rail 510' and disposed To maintain and prevent the bottom of the car wheel from being displaced off of the guide rail 592 there is provided a lower fence rail 513. The lower fence rail is secured to a plurality of brackets 514, one of which is shown in FIG. 8, which are secured to the top surface of the side members 503. The lower fence rail 513 likewise extends transversely of the base 489' from the outermost ends of the side members 503. Thus, a car wheel supplied to the guide rail 502 is maintained thereon in an upright condition by the fence rails 510, 512 and 513. As previously stated, the transfer mechanism 199 is located within the recess 501. To this end, the fixed guide plate 101 is welded to mounting blocks 516 which in turn are welded to the upstanding supports 504. The rollers 149 and the roller arms thereof are positionable into a car wheel engaging position, as shown in FIG. 8, or to a disengaged position below the transfer mechanism ltiil. The operation of the transfer mechanism is the same as previously described for the machine depicted in FIG. 1. In the modified example of the machine tool, the fixture head 497 is constructed so as to be maintained in a fixed position on the base 480. Thus, the fixture head 49? must be operable to receive and position the car wheel in axial alignment with the boring bar 485, and must also be arranged so as to provide a clear path of travel for a car wheel as it is moved along the guide rail 592. To this end, the fixture head 497 is provided with three clamping elements or jaws comprising a top or vertical jaw 518 and a pair of bottom or cradling jaws 519. In the interest of clearly showing the manner in which the jaws 519 are arranged for radial movement the lower right hand one of a pair of jaws 519, as viewed in FIG. 9, has been omitted, while the left hand one of the pair is shown in position. Furthermore, in order to clarify the illustration, the lower left hand jaw shown in FIG. 9 is depicted as being in a vertical plane in FIG. 10 although it is to be understood that the jaw is angularly displaced from the vertical plane, as shown in FIG. 9. Since both of the lower jaws are of identical construction the description will be limited to a single one thereof. As shown in FIGS. 9 and 10, the upper jaw 518 comprises a guide portion 522. which is supported for guided movement in a guideway 521 provided in the front face of the top overhanging portion of the housing 499. Integrally formed with the guide portion 522 and disposed perpendicularly thereto so as to extend outwardly from the face of the housing 499 is a body portion 523. The body portion 523 is elongated and extends beyond the guide portion 522 in a manner to provide a nose portion 525 to which is secured a jaw pad 526. The body portion 523 of the jaw 518 is constructed so as to be narrower than the guide portion 522, thereby forming elongated shoulder surfaces 527 and 528. To maintain the jaw 518 Within the guideway channel 521, a pair of retainer plates 529, one of which is shown in FIG. 9, are secured to the face of the housing 499 on either side of the guideway channel 521 in a manner to overlap the shoulders 527 and 528 formed by the outer surface of the guide portion 522 and the perpendicular body portion 523. An actuating lever 531 for moving the jaw 518 in its path of travel is pivotally mounted on a shaft 532 which is supported in a pair of spaced web members (not shown) formed within the interior of the housing 499. The lever 531 is provided with a short arm portion 533 the end of which extends outwardly of the housing 499 through an opening 534 provided in the face of the extending or overhanging porition. The outwardly extending end of the arm portion 533 is engaged within a recess 535 formed in the guide portion of the jaw 518 and is operably connected to effect movement of the jaw 518 downwardly or upwardly upon pivotal movement of the lever 531 about the shaft 532. The opposite arm or long end 538 of the actuating lever 531 extends inwardly towards the common axis to engage an operating cam member 530. The long arm 538 is maintained in engagement with the operating member 530 by a spring 548 which is maintained in position by rods 549 and 551 which are threadedly engaged in the housing 497 and the arm 538, respectively. The lower jaws 519 are arranged similar to the upper jaw 518 for radial movement about the common axis but are also arranged so as to be retractable within the interior of the fixture head 497 to provide a clear path for movement of a car wheel into or out of the position adjacent the fixture head 497. To this end, the fixture head 497 is provided with elongated angularly disposed side housings 536 and 537 in which are supported for axial movement, slide blocks 539 and 539a. As previously stated, the construction and operation of the lower pair of jaw members 519 and also the associated slide blocks 539 and 539a, are identical therefore the following description will apply to both. The slide block 539 is slidably supported within the angularly disposed side housing 536 for axial movement. The forward or outer face of the slide block 539 is provided with a guideway channel 540 which is similar to'the channel 521. Within the channel 540 a jaw clamp or jaw member 519 is slidably supported for movement along a line which passes through the common axis. The jaw 519 is maintained within the guideway channel 540 by a pair of retainer plates 541 and 542. The construction of the lower jaws and of the associated guideway channel are the same as described above for the upper jaw 518. .As shown in FIG. 10, an actuating lever 543 is pivotally mounted in an elongated axial opening 544 provided in the slide block 539, on a shaft 545 mounted in the slide block transversely of the opening 544. A short arm portion 546 of the actuating lever 543 extends outwardly of the face of the slide block 539 into a recess 547 provided in the jaw 519. The arrangement is such that pivotal movement of the lever 543 will effect a movement of the jaw 519. The opposite end or long arm portion 555 extends through an elongated opening 556 provided in an interior web portion 557. The web portion 557 functions as a wall of the housing in which the slide block 539 is mounted. The extending end of the arm 555 is disposed to engage the operating cam member 530 and is maintained in engagement therewith by a spring 558. The spring 558 is maintained in operative position by means of a pair of rods 559 and 560. The rod 559 is threadedly engaged in the arm portion 555 and the rod 560 is threadedly engaged in the slide block 539 in opposing relationship to the rod 559. The operating member 530 comprises a tubular member 563 having a frusto-conical end portion 564, the peripheral surface 565 of which constitutes a cam surface on which the ends of the actuating levers engage. The tubular operating member 534 is slidably supported Within a bore 566 formed in the housing 497 for axial movement. The operating member 530 is arranged so that its axis coincides with the common axis about which the jaw members are radially movable. A cap plate 567 is provided to cover the outer open end of the bore 566 and is secured in place by a plurality of screws 568. The cap plate functions to prevent chips, dirt and the like from entering into the bore 566. A rod 569, secured to the cap plate 567, extends inwardly and engages in an elongated opening 579 provided in the operating member 530 and functions to prevent rotation of the operating member 530 in the bore 566. The cam member 530 is movable axially by means of a fluid actuator 573 comprising a cylinder 574 which is secured to a back plate 575 that is fastened to the end of the housing 499. A piston (not shown) reciprocally supported within the cylinder 574 is provided with a piston rod 576 that extends inwardly through the backing plate 575 and through a bored opening in a back plate 577 of the cam member 530. The free end of the piston rod 576 is provided with a threaded portion which is threadedly engaged in a nut 578 contained within a reduced bore portion 579 provided in the operating member 23? p 530. The nut578 is provided with a boss580 which snugly fits withto the outer face of the rear wallj6l7. A piston (not 7 shown) is reciprocally supported withinthe cylinder 6fi9 in a reduced opening 581provided in the end of the p- 9 i erating member. =Thus, the nutJ578 engages against *a a circular flange 582 formed by the reduced opening 581. A plurality of screws 583 are insertedthrough suitable ',openings in the back plate 577 into threaded engagement with the nut 578v and elfectively lock/the back plate 57 7 and the -nutf578 to thefo'perating member 530; The back i plate57-7 and the nut 578; constitute an operable'connection whereby the fluid actuator 573 may impart reciprocal motion to the'operating niemberSSt). A fluid motor 590 is employedto reciprocate the slide and is "provided with a' piston rod 611 The piston rod 611 extends inwardly through a suitable opening in the rear wall 607 and is operably connected to the rod 606. The fingers are actuatedin a locating action with sufiicient force to bring the car wheel into engagement with the pads 6M, dill and 6:93, but are not operable to effect a clamping of the wheel thereto. 1 r In operation, assuming'thatthe lower jaw members are in a retracted position andjthe boring head is retracted, the transfer mechanism-109 will be aetuated to pivot the rollers 149into'posi'tion to engage car wheelsin the loadblock 539 and comprisesa eylinder 591 whichis secured V to a closure, plate 592. The'closure plate 592 functions to seal the end opening of. the housing in Whichthe slide block 539 islcontaincd. The inner surface of the closure plate 592, is provided with a hollow hub member 593 hay: ing a cap plate 594. A piston (not shown), reciprocally supported within the cylinder 591 is provided with a pistonfrod 595 which extends. inwardly through suitable axiallyaligned, openings in the'plate 592 and the capplate 594. ;The free end of the rod 595 is provided with a threaded portion which is'threadedly engaged in;a- 'suit-, able threaded openingin the end of the slide block 539;. The rod 595, adjacent to the opening inthe cap plate 594; is provided with a threaded section 59 6 on which an adjusting, nut-597 is threadcdly engaged. By adjusting the nut 597 on the threaded portion 596' of the. rod 595, forward or outward movement of the slide block 539'may be limited so that the fluid actuator may move the block 539 only a distance suificient to position the jaw member 519 outwardly of. the faceof the fixture head Y497 and into the plane in which the jaw member 518 is located. A similar, actuating arrangement isprovided for/the slide block 539a. While individual actuators have been employed for each slide block, it is apparent that 'both, slide locks may be connected togeth'er by'means' of a yoke bar connected to the actuating rods and a single actuator then could be employed for moving both of.the slide blocks.- V j j j The slide block 539, when actuated in a retracting movement, will operate to move the actuating lever- 543 with 'loadingstation into the work station. of the'transfer mechanism 160 will then be pivoted into a retracted position andthe transfer mechanis'rn reset for ing station and in the work station, and'will then be actuatedto advance the car wheels along the guide rail "5E2 so that a finished wheel in the work station is moved out of-the station and anew wheel is movedfrom the The rollers 149 anothercycle of operation, r ' After the transfer mechanism 100 has, been reset, the slide blocks 539 and 539a are advanced to move the jaw members thereof into position, whereinthey may be engaged with the car wheel. Simultaneously with the advancement-of; the slide blocks 539 and 539a, the fingers 691, 6tl2'and 663 are actuated to locate the car wheel against the locating pads 511,598 and 599;""This insures that the axis ofthe car wheel willbe disposed in a plane it as well as the jaw member 519. The jaw member 519 I will then be recessed within an opening 589 provided in the front face of the angular side portion 535. Thus, the jawfinember 519 is moved to provide a clear pathlfor movement of a car wheel into the fixture head 497. Since both of the lower jaw members operate in the same u manner, a clear egress path ,is also. provided for movement of a car wheel out of the fixture head. e As shown in FIG. 9,, a pairof locating-pads 59 8 and 599, are secured to the faces of the angularside housings above the jaw members, The three locating pads 511, 598 -and'-599 function to orientate a car wheel in a vertical plane to insure that the axis of thercar wheel, when in the. work position, will be parallel to the axis of the boring 7 bar 485. To locate a car wheel against the pads 511, 598 and 599 a plurality of'fiugers 691,662 and 6% are: provided. 5 The fingers 601, 602 and 663 operate. to enparallel to the axis of the boring bar 585. When the car wheel has beenorientated, the operating cam'member 531' will be actuated rearwardly, to the position "SlTOWIl in FIG 10, causing the actuating levers 53-9, 543 and 543a to pivot about their respective shafts. This pivotal move- .ment effects radial movementof the jaw members inwardlygfito effect'a clamping of the wheel to the fixture head 4) a 1 The lower pair 'of members 519 act to cradle the car wheel'and to slightly raise or elevate the car wheel off of the gu de rail 5912. This action brings the axis of the car wheel in alignment with the axis of the boring bar 485; The tool head'481 is'then advanced to feed the rotatingboring bar'tothe car wheel. Assuming that the car wheel in the fixture head 497 is offa size wherein the cutters 437 "are tobe employed, the head 481 is advanced until these cutters have completed a work operation. Thuathe forward cutters 486 will'be niovedthroug-h the wheel and extend into the recess or passage 501 to permit the cutters 457' to operate on'thecar wheel. Upon completionof the work operation, the" tool head'481 will be retracted'to move the boring bar clear of the car wheel. Thereafter, the operating cam member .530 will be movedin the opposite direction and theactua'ting arms 531,543 and 543a Will be pivot'ally moved in the opposite-direction by action of thesprings associated with the individual arms. Thiswill effect radial movement 7 of the jaw members outwardly to release the car wheel. gage the car wheel and move it bodily so that the face e of the car wheel adjacent the fixture head 49.7 will engagegf against-the, locating pads. V The fingers 601,6 l2 and 693 are identical and therefore a descriptionof one will apply to all. 1 Asshown in FIG. 10, the finger 602 is secured to the extending end of an actuating rod 606 which extends through V a suitable opening (notshown) provided in the fence rail 512 and whichis sufficiently large to permit of movement 7 of the finger 692 therethrough The'lrod 606 is slidably supported in the housing 499 and extends therein to a rear wall 607 thereof. A fluid actuator 608 .is proyidedfor aotuatingthe rod 606 to effect engagement anddisengagement of the finger 602 with the car wheeLj .Thefiuid actuator'608 comprises acylinder 609 which is secured When the car wheel has been released, the fingermenibers 6-91, 692 and 693. are moved outwardly, out of engagement with thelwheel) Simultaneously therewith'the slide blocks539 and 539:: will be, retracted moving the'associated jaw membersinwardly into the housing 499 thereby clearing a path for subsequent movement ofthe car wheel out of the fixture head and a new car wheel into' the fixture head. ' From the foregoing detailed description of the structure 25 pletion of a work operation thereon while simultaneously moving another car wheel into the work position. Although the illustrative embodiment of the invention has been describe-d in considerable detail for the purpose of making a full disclosure of a practical operative structure, it is to be understood that the various novel features of the invention may be incorporated in other structural forms without departing from the spirit and scope of the invention, as defined in the subjoined claim-s. The principles of this invention having now been fully explained in connection with the foregoing description, we hereby claim as our invention: 1. In a machine tool for performing a Work operation upon a circular workpiece; a base; a tool head supported on said base; a cutter rotatably supported in said tool head; a work fixture mounted on said base; said tool head and said work fixture being constructed and arranged so as to provide for relative movement therebetween; a workpiece guide secured to said base and dis-posed between said tool head and said work fixture transversely of said base in position to rotatably guide a workpiece into a predetermined work position between said tool head and said work fixture; a transfer mechanism carried by said base and operable to roll a workpiece into the work position and a finished workpiece out of the work position simultaneously; a chuck mechanism carried by said work fixture and operable to receive and clamp a workpiece in the work position to said work fixture; a backing plate yieldably carried by said tool head forwardly thereof and being operatively disposed to cooperate with said transfer mechanism and said chuck mechanism in a manner to support a workpiece when in the Work position in an upright position and operable to maintain the workpiece therein; and power means operably connected to eifcct relative movement between said tool head and said work fixture to effect a work operation on said workpiece. I 2. In a machine tool; a base; a tool head fixedly mounted on said base; a cutter rotatably carried by said tool head; first power means carried by said base and operably connected to rotate said cutter; a fixture head movably supported on said base for movement toward or away from said tool head; a plurality of stations on said base comprising a loading station, a work station and a receiving station; guide means carried by said base and extending transversely thereof through said stations between said tool head and said fixture head; a transfer mechanism mova-bly supported by said base and operably disposed to move a workpiece from said loading station to said work station and a workpiece from said work station to said receiving station; a chuck mechanism in said fixture head operable to engage and hold a workpiece in a desired position relative to said cutter; second power means connected to actuate said chuck mechanism; third power means connected to move said fixture head into position to cause engagement of said chuck mechanism with a workpiece in said work station for securing the workpiece to said fixture head, said third power means being further operable to move said fixture head toward said tool head to feed the workpiece held in said chuck mechanism in a work operation to said cutter; whereby a workpiece in said loading station may be advanced to said work station and the fixture head may be advanced to engage the chuck mechanism with the workpiece to securely hold the workpiece to the fixture head and thereafter the fixture head may be advanced to feed the workpiece to the rotating cutter in said tool head for a work operation. 3. In a machine tool for performing a work operation on a circular workpiece; a base; a tool head supported on said base; a cutter rotata'bly supported in said tool head; a motor mounted on said base and operably connected to rotate said cutter; a work fixture mounted on said base for reciprocal movement toward or away from said tool head; guide means carried by said base transversely thereof and disposed between said tool head and said work fixture to rotatably guide the workpiece into a work position between said tool head and said work fixture; a transfer mechanism movably supported by said base in position to roll the workpiece along said guide means into the work position in a controlled movement; a yieldable backing plate carried by said tool head forwardly thereof in position to support the workpiece in an upright position on said guide means in the work position; said backing plate being disposed to cooperate with said transfer mechanism during a transfer movement; a first power means connected to advance said work fixture toward said tool head to a position adjacent the workpiece; a chuck mechanism carried by said work fixture and operable when actuated to receive and clamp a workpiece to said work fixture; said chuck mechanism being operatively disposed to cooperate with said backing plate; a second power means carried by said work fixture operably connected to actuate said chuck mechanism; said first power means being also operable to advance the work fixture and the workpiece thereon toward said tool head to feed the work piece to said cutter in a work operation; said backing plate yielding upon the advancement of said work fixture to permit of the feeding advancement of the workpiece to said cutter. 4. In a machine tool for performing a work operation upon a circular workpiece; a base; a tool head supported on said base; a tool rotatably supported in said tool head; a fixture head supported on said base in spaced facing relationship to said tool head; said tool head and said fixture head being constructed and arranged so as to provide for relative movement therebetween; a workpiece guideway on said base disposed between said tool head and said fixture head transversely of said base and extending outwardly from both sides of said base; a transfer mechanism carried by said base in position to advance a workpiece on said guideway in a controlled rolling movement into a work position between said fixture head and said tool head and a finished workpiece out of the work position simultaneously; a chuck mechanism in said fixture head operable to receive and clamp a circular workpiece in the work position to said fixture head; means engageable with a workpiece in the work position and operable to position the workpiece so that its axis is parallel to the axis of said tool; power means in said fixture head operably connected to actuate said chuck mechanism in a clamping or unclamping action; power means on said tool head operably connected to drive said tool; and power means in said base operably connected to efifect relative movement between said fixture head and said tool head. 5. In a machine tool organization for operating upon a circular workpiece; a base; a workpiece guide means carried by said base transversely thereof; a plurality of stations spaced along said guide means comprising a loading station; a work station and a receiving station; a Work fixture mounted on said base on one side of said guide means at said Work station; a chuck mechanism carried by said work fixture and adapted to receive and clamp a workpiece to said work fixture when said workpiece is in the work station; power means carried by said work fixture and operably connected to actuate said chuck mechanism in a clamping or unclamping action; a tool head mounted on said base on the opposite side of said guide means at said work station; said work fixture and said tool head being adapted for relative movement in respect to each other; a cutter rotatably supported in said tool head for performing a work operation on the workpiece; power means carried by said base and operably connected to drive said cutter carried by said tool head; a transfer mechanism carried by said base in position to roll a workpiece from the loading station into the work station and a finished workpiece out of the work station into the receiving station when coupled to workpieces in said stations, said transfer mechanism comprising; a first member adapted to be moved axially; power means connected to move said first member axially; a second member ad-

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