US2386990A - Hydraulic system - Google Patents

Description

Oct 16, 1945- -A H. lswENsoN l-:ALI

HYDRAULIC SYSTEMl 3 Sheets-Sheet l Filed July 8, 1942 @ria oct. 16,y 1945.

A.' H. swENsoN ETAL HYDRAULI C SYS TEM Filed July 8, 1942 -5 -Sheets-Sheet 2 INVENTORS. l

Zd/21101K @zz/621507, Qzzdemw.

'Oct' 16, 194,5. A. H. swENsQN ir/ilu.4

HYDRAULIC SYSTEM Filed July 8, 1942 5 sheets-sheet s Patented ct. 16, 1945 Vnrnimultic SYSTEM Arthur H. Swenson and Phillip A. Anderson, Rockford, Ill., assignors to Sandstrand Machine Tool Co., Rockford, Ill., a corporation'of Illinois Application July 8, 1942, Serial No. 450,134

18 Claims.

The invention relates generally to hydraulic systems and more particularly to hydraulic systems particularly adapted for driving a carriageV or other member of a machine tool.

One object of the invention is 'to provide `a hydraulic system including a transmission operable over a range of feed rates and having dog or automatically operated control means for causing the transmission to operate at a predetermined' feed rate and means permitting manual control obtaining operation of the transmission at any desired feed rate within said range.

Another object is to provide such a hydraulic system wherein the previously used feed' rate is available again for automatic control after, the use of manual control for the same or other feed rates.

Another object is to provide in such a hydraulic system an optionally operable manual control means having a handle shiftable from a neutral position to different forward and reverse feed positions on opposite sides of the neutral position,l

the feed rates being somewhat proportional to the distance the handle is moved from neutral position.

Another object is to provide a hydraulic system including a transmission operable in forward or reverse over a range of feed rates, hydraulically operated means causing operation of the transmission in either direction at a predetermined feed rate, and means relieving the hydraulic pressure in the hydraulically operated means to permit direct manual adjustment thereof in either direction and to an extent obtaining any feed rate within the feed range.

Another object is to provide in a hydraulic system operable over a range of feed rates andhaving control means including a fluid pressure actuated stop determining the preadjusted feed rate, means for relieving the fluid pressure on the stop to permit direct manual adjustment ofthe control means throughout the entire range of feed rates.

Another object is to provide in a hydraulic sys-l tem, i including a transmission having a main pump and a motor operating in a closed circuit and a pump for supplying makeup uid,a valve means operable to interconnect the inlet and outlet portsof the main pump and to connect the same to tank through a restricted orifice.

A further object is to provide in a hydraulic system, having hydraulically actuated control means and means for relieving a part ofthe control means of hydraulic pressure to permit directI manual operation, valve means associated with a remaining part of the control means permitting discharge of uid under pressure generated by manual operation of the control means.

Other objects and advantages will become apparent from the following description taken in connection with the accompanying drawings, in which:

Fig. 1 is a diagrammatic view of the hydraulic system with the transmission shown partially diagrammatically and partially in actual construction, and with certain valves enlarged better to disclose annular recesses and grooves thereof. The system is shown in its neutral stage.

Fig. 2 is a diagrammatic View of the hydraulic system similar to Fig. l but showing the system in hydraulic control stage. l

Fig, 3 is an enlarged view of the main valve in one of its rapid traverse positions.

Fig. 4 is an enlarged view of the 'changeover valve in its energized position. a

Fig'. 5 is an enlarged view of the shunting valve in its deenergized position. Y

Fig. Gis an enlarged View of the pressure reducing valve in a position which it assumes temporarily during direct manual control of the hydraulic system.

Fig. 7 is a front elevational view of a machine tool carriage or table, partly in section and diagrammatic.

While there is illustrated in the drawings and will hereinafter be described in detail a preferred embodiment of the invention, it is to be understood that the invention is not limited to the particular embodiment and arrangement shown. On the contrary, it is contemplated that Various changes may be made by those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

The system includes a fluid transmission comprising a casing 20 having a detachable end member 2l. The lower portion of the casing is occupied by a pump P and the upper portion by a motor M. A single cylinder block 24 is secured in the casing and has an annular series of pump cylinders Z and an annular series of motor cylinders 2l formed therein. Pistons 28 in the pump cylinders are arranged to be actuated by means of a wobbler device 29 which is pivotally mounted on a drive shaft 39 by means of a pin 3|. As illustrated in Fig. 1 of the drawings, the wobbler 29 is shown in a neutral position, the wobbler being adjustable angularly in both directions from the neutral position to provide for reversing the flow of fluid from the pump, as well as adjusting the output volume of the pump. The shaft 30 is rotatably mounted in the casing and in the cyland the motor operate.

y, A. meeste The inner surface 42 of the end member '2l is I adjusted so that the valve 13 opens on prssures in excess of 150 pounds per square inch. This valve is connected in the output circuit of the pump 10 to limit the pressure of the makeup and control fluid.

In actuating a table or other support of a machine tool, it is desirable to obtain a plurality of relatively slow feed speeds fand also ia relatively high or rapid traverse speed. For convenience table will hereinafter be employed to designate the part or element driven by the transmission.

preferably flat and formsfone wall oi a valve l chamber 43, in which the valveso'f both the-pump The cylinder 'block 24 is recessed as illustrated to provide an opposed flat surface 44 forming the opposite wall of -the valve chamber. Operable in the lower portion of the valve chamber 43 and to control the `flow of. nuid to and from the pump cylinders is e. wheel-like valve 45 of the type more fully disclosedfand Vclaimed .ini U, S. .Letters Patent No. 2.190,812, 'of Gunnar A. Wahlmark, .dated February,20, .1940. This valve is mounted .on .an eccentric 46 on the shaft 30 and is operable Ato connectv the .pump cylinder .ports 41 alternately tothe peripheral .portion 48 of the valve chamber or .to .aninner annular passage 49 in the valve. Operable in .the upper .portion ofthe valvechamber' i3V is a wheel-like .valve .5D for the motor.

This valveis mounted on .an .eccentric pin .5l on the. motor shaft andI is operable during rotation -of the -shaft to connect theV motor lpiston ports '52 alternately to the peripheral portion 53 of Vthe valve chamber A'or -an inner vannular' .passage 54 inthe valve. will be `apparent. from the drawing,V the -provision of .a commonlvalve chamber for the pump `and valves provides adirect -connection for the Yflow -of fluid from the pump to the motor (or vice versa) -through the narrow -midportion of the `vvalve chamber. A second lpassage 1for the now .-of -iud between the pump andthe motor is .providedinthe end member 2l at 55, this passage having -anannular Dertien- 55 in the Vlower -part ofthe end member communicating with the .inner passage 4.9 of the valve and having an annular portion 51m-the upper part of :the end vmember communicating with theinner passage :p54 .of the `valve 5U.

:A1, pairr of high ,pressure -relief valves 6U and .6l area-provided to limit the pressures in .the passages between thepumpandmotor. These .val-ves arexnormally held :seated by means vof coiled springs 64 andsli5.- The connection between lthese high pressure relief valves-.and the passagesbetween thev pump andthe motor will be more fully described in .connection with `the description 4of theoircuit.

nfBrefera-bly, arotary -pump .1B is mounted on the casing il and driven lfrom the yright handend of Ithe. pump shatt 3B. `The pump v13, as .illustrated is sf tnrorm.-s hown m U, s. LettersPatent No.2.,11e2;13,of Gunnar A. Wahlmark, dated Qctober ill, 1.938, tand* serves .to :supply uid at approximately -150 pounds per square inch pressureftoitlleipurnp-motor circuit to maintain this circuitfuilwat alltimes and for 4actuating control .fmechanisrns Cooperating with the .pumpy 1.0.;to vmaintain the gpump-motor circuit full of luidxare Va ;pair .ofcheck valves 1I and 12, the operation-of which, .as-well as the now. of fluid from the pump 10,will .be ldescribed in greater particularity hereinafter. Preferably, ,a .relief va'lve 113v is Sbackedgby a @spring-14 which may ,be

Also .for convenience, operation of the transmission in one direction or the other will be desig- :nated in terms of forward or reverse movement of the table. Tit is to be understood, however', that "any-character of support or element, whether reciprocatory or rotary, and whether a part of a machine tool-or some other mechanism, is intended. While the pump P and motor M combine to provide a large number of diierent speeds of the motor .shaft v35, ,an additional 4means is provided for .utilizing these motor shaftspeeds for obtaining traverse movements -of Ythe table and for reducing thesespeeds still :further `toobtain feedmovements. To that end, the tra-nsmission .includes .a planetary gearing, generally designated 15, operatively interposed .between the kmotor shaft 35 and a ydriven .shaft .16, `journaled in a ball bearing 11, in alignment with the motor shaft. This gearing may .take any one of a number of well known ,forms -but preferably comprises a sun gear r1.8 formed on the .endof the motor shaft 35, one .or more .planet gears 19 meshing with the sun gear 1.8 .and rotatablysupported on a radially .outwardly projecting flange 80 formed on the .inner end'of `.the shaft 16. .The planet gear 19 also meshes with a ring gear 4M which is slidable longitudinally inthe `casing-82 surrounding the planetary gearing. The gear Bl has an integral inwardlyand thencelong-itudinaL ly extending annular flange 83 `carrying an an nular .piston 84 reciprocable lin a cylinder85. The ring .gear .has an outer vbeveled annular brake face .36 engageable with aY corresponding lbeveled stationary brake ring 81 when the piston B4 is moved toward the vright .in Fig. l. The .ring gear 8l alsocarries anannular clutch member Vfilipino-- vided with a beveled face 89 engageable with .a corresponding beveled .clutchgface 90 on the `flange .of the shaft 16, so .that A.when the piston v824 is Vmoved toward .the .left theclutch faces r8.9 and 9B are engaged and .the planetary gearing .elements are locked .together .to lrotate as ia unit. Under this condition, Vthe driven shaft .16 will rotate in unison with the .motor shaft .3.5.- .With the .ring ,gear held stationary .against the brake ring 851, the .driven ,shaft 16 will .be-operated at a speed lower than that .of the .motor shaft J3.5 due .to the reduction .caused by .the planetary gearing which .is .then :free to operate.

In Fig. 7.-, by .way .,offillustra'tion, .there .isdisr closed one .form `of tablesuppcrt .or .carriage .that may be actuated Aby the transmission. .Represented is va milling .machine ltable.35 .and suitable gearing for driving thesame from the .driven shaft 16. .At its ends .the Ytable .has depending end .brackets 35| and 352,suitably bolted thereto. A eedscrew .353 Ais rotatably mounted in `these brackets and .has .squared .ends .354 .enabling it .to be .rotated manually Vfor set up adjustments. The .screw 353 .passesthrough a pair .of spaced stationary nuts 355 secured to thelbed 356 of the machine. K

A .drive .gear `35,1 is .slidably keyed Ato .the .screw and ,is .rotatably .mounted on the .bed 35E'. `llrxe drive from 'the transmission shaft 16 tothe-screw isfcompleted by suitable. gearing lindicated by the numerals 358, 359,360, 36| and 362. .LThisgearing connecting the transmission shaft16rtoithe table is shown by way of` illustration..I herein and forms the-subject matter of a copendingf application of.Y Gustaf H. -Ekstrom l and' Bengt R.

Granberg, Serial No. 323,780, filed March.13,A

the-wobbler device so that movement ofthe member III toward theleft-from the position shown inthedrawing pivotsthe wobbler `device inra clockwise Ydirection tocause a flow of iiuid-'from the pump to the motor, operating .the'motor inl a forward (table) direction-whereas, movement,` of the member towardv the right rotates the wobbler device in a counterclockwise direction, causing a` reverse-now of fluid from the pump to the motor and a reversal of the motor and tableV movement. A tubular control member I I for-the pump is slidably mounted in a bore lII6 in the cylinder block 24- and is'connected with the .member byfmeans of a ball bearing I|1. `The control member |I5 has a radial bore therein1 andinto this bore extends one end of a lever IIS'pivotally` mounted intermediate its ends on a pin |20. The motor wobblerfdevice 39 has a similar slidable -control` member |22 positioned in a keyway |23 in the motor shaft 35 and provided with an 'outwardly extending arm-Y |24 which engages in a bore in the'wobbler device. A tubular control member I26 is slidable in a `bore |21 in the cylinder block 24 and is connected to the .member '|22' by vmeans of a ball bearing |26. Thetubular member |26 has a radially extending bore which receives onev end of a lever |30 pivotally mounted intermediate its ends on a pin'Y |3I.

.'JIn theform illustrated herein, the pump control lever IIS andthe motor control lever v|30 are arranged to be operated by piston andcylinder devices-and, furthermore, are arranged to have their operative positions determined by ada ditional piston and cylinder devices. Thus, the remaining end of the lever ||9 extends into a diametricalbore in a piston |4| which isl slid-..

ably mounted in a cylinder |42. lThe remaining en'd'of thelever |30 extends into a diametrical tween the pistons |4| and |41 permits actuationv of 'the lever IIS by the piston |41, as well as by the piston .I4I. For convenience the `pistons |4| and |41 or the devices of which they form a part will bevknown as reversing or rack pistons or devices, while the piston |44 or the device will be known as the main neutralizing piston or device.

"Parallel to but midway between the 'aXes of the pistons |4| and |41 is a-cylindrical bore I 51 partially lined with a Y sleeve l I 56.

shown in dashedY A cylindrical of the right hand ends of the pistons |4| and |41. The plunger |58Iis connected to the piston |44 by means of a'lever |59 which is pivoted intermediate its ends on a pin |34. lThe upper end of the lever |59 enters a bore |60 in the `piston |44, whereas, the lower end of Athe leverenters a boreV |6| in the plungerv |53. The piston |44.has av slightly smaller pressure area than either of the pistons lI4| or |41, andherein is operated by fluid at 110 pounds per square inch pressure, whereas pistons |4| and |41 are operated'by uid at 150 poundspressure, sothat when. thepiston |44 and one ofthe pistons |4| or I41.are subjected tofluid pressure at thersame time, the piston |4| or" .|41 will control-The connections just described are s'uchthat, by-sup.-

plying iiuid to the cylinder |42 through a port:

|62, the piston I4| will be moved toward the 'right' and will cause a swinging movement of the pump control lever ||9 in a counterclockwise direction, thus causing a movementof the tubular control member ||5 towardthe left and an adjustment of the wobbler device 29.in a .clockwise direction about the pivot 3|. If iuidl is supplied to the cylinder |46 through a port |63, the rack and pin,- ion connection will cause a movement of the piston |4| toward4 the left, thus causing an adjustment of the wobbler device 29 inra counterclockwise direction from that shown inthe drawings. Regardless of whether the piston |4| moves to the right or the piston `|41 moves to the right,

the plunger |58.will Abefm'oved to the right and,

through the intervening lever |59, -piston |44, and lever |30, will cause an adjustmentoflthe motor control member |26 toward the rightfrom the position shown in the drawings, so as to reduce the stroke of the motor pistons asthe stroke of the pump pistons is increased.

tion, the direction of rotation of the motor shaft will be reversed rwhen the fluid flow from the pump is reversed. The plunger |58 may for convenience be referred to as the auxiliary neutralizing plunger.

The extent to which the pump and motor web-1 bler. devices are pivoted by action of the pistons I |4| and y|41 is at timesr determined by an additional piston and cylinder device mounted inlan auxiliary casing supported from the casing 20.

To that end the casing |55 is formed with a bore.

|65 open at its left hand end, as viewed in Fig. 1,

' to the sleeve |56. Reciprocable in the bore isa hollow piston |66 formed with a recess |61 opening through the left hand vend of the piston, as viewed in Fig. 1, and closed after assembly of the device by a plug |68.. Suitably mounted in the ycasing |55 in threaded engagement therewith is a screw adjusting device |69projecting through an aperture |10 in the piston |66 and formed at the end projecting into the recess of the piston with a head |1| larger than the aperture |16 so as t0 limit inward movement of the piston |66. At its outer end the screw device carries a suitable cap nut |12 which may be manually or through'- mechanical means rotated to adjust the screw |69 t0 the desired longitudinal position. As described more fully hereinafter, iiuid may be supplied to the right hand end of the bore through a port |13 to maintain the piston |66 in its left hand or pressure actuated position as determined by adjustment of the screw device |69. lThe piston |66 thus'is operable to limit the movement .of the,

plunger |58 is slidablyV mounted in the sleeve |56, rand at its left hand end projects into the paths Since thei movement of the motor wobbler device 30 is always in the same direction from a neutral posithe tank `through a conduit 250 open to the bore through the end thereof and thus in alignment with the passage 249. Valve bore 244 is formed with three annular grooves 25|, 252 and 253. These grooves are so spaced axially of the bore that groove 25| registers with recess 2141, while grooves 252 and 253 are bridged by the recess 245 when the valve is in the position shown in Figs. 1 Iand 5. When the valve isshifted upwardly to the position shown in Fig. 2, grooves 25| and 252 are bridged by the recess 245, while groove 253 is blocked. Independently of the valve 243, vgrooves 25| and 252 are constantly interconnected by a passage 255 having interposed therein a restricted orice 256.

The groove 252 is by a conduit 251 connected to the conduit 235 and groove 253 is by a conduit 258 connected to the conduit 231. It will thus be seen that when the valve is in the position shown in Fig. 1, wherein grooves 252 and 253 are bridged, the ports of the main pump P have been connected together sofas to form a shunt circuit about the motor M. Thus, should there be a slight discharge even though the wobbler 29 is intended to be in `absolute neutral position, the fluid will merely ow through the pump and the valve means 282 and there will be .no creeping of the table. It is to be noted that under this condition the main pump P is through the passage 255, the orii'ice 256, and the annular recess 241 imately eighty pounds per square inch, which isA lower than the control pressure maintained by the makeup pump relief valve 13, and thus reduces the .work done by the pump when the system is in neutral.

The orice B and the passage 255 serve an additional function. When it is desired to move the table by hand, the prime mover driving the pumps P and 18 is stopped, while the valve means 202 is retained in the position shown in Figs, l and 5. Under those conditions, actuation of the transmission by hand forces the oil to the tank through the orice 256 and the passage previously described, so that after one revolution of the transmission all the oil is discharged therefrom and movement of the table by hand is effected with little effort, because'it is no longer necessary to force the oil through the transmission itself.

The valve means 282 may be controlled in any desired-manner. Herein, however, it isV for purposes of illustration disclosed as actuated electricallygthrough the medium of a solenoid259 under the control of a switch 268 appropriately .connected in electrical circuit with the solenoid 259. The valve 243A is shifted .to its upper position when the solenoid ,is energized and is returned by gravity or equivalent means to its lower position when the solenoid is deenergized. As already described, the valve is shown in its lower or deenergized position in Figs, l and 5, and is shown in yits energized or upper position in Fig. 2. 1 Normally, the various devices determining the direction and rate of operation of the transmission and hence the direction and rate of movement of the table or support driven thereby are hydraulically actuated and governed under the control of the main valve means |19. To `that endl groove |92 isby a conduit 265 connected to conduit 266VA connected -toport |153' ofcylinder |46. Groovev |95-isby a conduit261'connected to a port 268 discharging to one' endofcylinder constituting* a part of the 'actuating means for the planetary gearing-'15. A port 269 commu'- nicating With the opposit'eend ofthecylinder 85 is by a conduit '210 connected toannularfgroove of4f the valve means |19. The remaining an"- nularQgr-o'ove |9| ofthe valve `means |19`is` bya conduit 21| and by aconduit 212 adaptedfat times to 'be connected to a port 213openingto the bore ||5rbetweenv the plunger' |58 and the'piston |66. Similarly, groove |96 I'of-,the valvemeans I 19 `is adapted at times vtobe connected Withthiport |13 opening to the b ore |65 "at the extreme right handV end thereof; asl viewed-in` Figs'l and f2. This communicationlis effected by'mean's including a conduit 214 communicatingat oneendwith the conduit 21|) and a ccnduit'215`comi'nunicating at one end with the port-113;"v "Tf The main valve means llii'falso controls the pressure directing "valve means `2 0 simultaneously and coordinately vvith'thereversingy pistons-14| and 141.` 'To that end',"`a conduit r`21|5gb'ranches from the conduit 285. and communicates'lwithla port 211 opening through one vendiof'a1oo1jef`f21f8 in which is reciprocablea cylindrical -Iv`alve "2 19. Branching from the conduit 266 is' a conduit-288 connected to a port 28|v openingYy through "the opposite end of the bore 218., Intermediate'its ends the bore 218is formed with three equally spaced, annular` grooves 282, 283 and 284IlY`The outside ` grooves 282 and 284 areby conduits-285 and 286'connected, respectively, to the conduits 235 and 239, thus providing connectio'nto voiaposte sides of the closedtransmission circuit. v"if-'lie intermediate groove283 has leading"therefron` a conduit 281, and interposed` inv this ,conduit-is ya check valve means, generally'y designated 288. This Avmeans provides a valve s'eat 289vag"ainst which a check valve 290 is constantly-urged joya compression spring 29|. AIt-,will be4 appreciated from a consideration ofligs. 41 or 2that'lthf'e check valve is so disposed astoxpermit nowfin, a direction away from the lgroove 283"but to prevent ow in the opposite direction.l Limitedfow in this opposite direction is permitted bythe provision of a small oricef292 formed centrally of the check valve 298. Valve 219 has a singlewide control recess 293. y f "I Though already describedyit is believeddesirable to mention briefly at this, point vthals",durf ing operation of thesyS'em underfthe control of the main valve means |19, control fluidfwill be supplied to one orthe otherrof. the cylinders |42 and |46, thereby 'urgingthe associated piston to the right, as viewed in ZEig.1, andt,hus either directly, if the piston |4lisactuated, or through the pinion |59, if the piston |41 is actuated, pivoting the'lever |9 to tilt thewobbler 29 for for,- Ward or reverse operation, of the pump. Such shift .of the pistons |4| or |41 willin turnact toA shiftthe plunger |58 andthroughglever |59, piston |44, and lever |30 tiltthe 'wQbble'I.38 of the motor. It will be seen that the direction of the tilt of the wobbler for thepump isdeter.- mined by which of the pistons |4 or .|41 is actuated, but that the ,.,wobbler of4 the motorv is tilted in but one direction. The extent oftiltfofboth wobblers is determined by the pistonv |,66and the adjustment of the screw device. |69. IfY ther-ight hand end of thebore |65 is connectedV to tank, the plunger |58 may, ofcourse, be shifted 'themaximum distance to the right, resulting in maximum displacement of .the -pumprand .minimum displacement of the motor, in other Words, to ahi-gh trate of operation -of thetransmission. This is :herein accompanied Yiby :suchadjustmentof the 'fplanetaryfgearing .as will produce rapid traverse .movement of the table .or other :support .actufated .by ithe'transmission. VShould control presfzsurewhe .supplied to Ather-right hand end ofthe .bore 4165, the piston 1166 would -be shifted to the deft to the extentpennitted by. engagement therefo .the head ofthe screw device |69. Movement of the plunger |58 to the right would .hnliche .limited :by its engagement with the piston |85, and thus vresults Lin Aoperation v-of the -transmission at sa :particular .frate predetermined und iixediay adjustment-of the'screw device 1'6-9. wherein-disclosed, control uid at the' same time :supplied .to the 'actuating means for the planetaryfgearing `so :as to adjustl 'the same `:to .obtain e. feed zratcof r"operation of .the transmission. Thus, though `.the :rate .ofoperation may he storied throughout the entire range of the transmission :by adjustment of lthe .screw .device 158; yonce that adjustment .haslbeen determined,

the :system will, when operating "under the conl ftroljiof -thesmain valve A18, operate-either at the .rapid :traverse :rate of .the transmission :or at -a particularpreadjustedieedrata While-contralor the various piston :and culin- .der devices v.determining the rate and direction of :drive-.of :the transmission .is normally hydraulical under the control of ltheunain valve `means 413, :provision is-herein made -fo-r .manual control of the svobbler devices 2.9 and 39 iby means including thel .handle |51', .for `:obtaining any Afeed rate V-of movement withinthe .range of the transmission. Tosthat fend, the-changeover valve .means 203 .and the pressures. relieving valve (means 2M -are `provided;N yThe 1changeovervalve means comprises ocylindricalvalveS-.slidahlein a bor-e30 The valve 4is provided 'with three comparatively wide,

.recesses 302, 303 and-@Lanci approxisix :annular grooves 308,309, 3H), .3| 312 .and 'f "3T3, all of the same Width as therecess .in the walve.. YOf these grooves, therst four-*are equally/spaced near theupper end oi .the .bore 301, while the llat'ter ltwo lhave Vthe .same .spacing .as

the .other ffour, 'butare .separated from .the :drst

named -four. The openings .to thehore are .coruple'ted by .a .port 3 |'4 Vopening .through the .end of thel'bore and connected bya conduit-3415 .to the tank. .''Ihe recesses and -the .groovesareso .posi- .tioned 'that in fthe upper. position --of the valve, thatj's, the -position-shown in Figs. l .and 4, grooves T309 .and 31.0 willb'brdged by the recess groove 311. will register with recess Bilde-nd 'thus e.connected.toftanlnv and groove '3|3 will vtbe:uncovered and thusalso, beconnected to tank. "Inthe lower `position of the .valli/e, that is, .theposition shown in Fig 2., sroovesjesand 39s .will bridged'by the recess 302,. grooves 3 l0 and .3 li .WIllbe bridged bythe recessj 03, .and-grooves .312

and 313 .will he `hridgedby therecess 304, thus leaving nogrooveiin vcommunication with the lonv .'gi'tudinal,pa'ssage 3D1. of the valve- The valve may be .actuated many-desired manner, 'Ii-is ior .purposes of `disclosure, however, herein yshown vas actuated. electrically Shy .a .solenoid v315 under the control of a switch -3|1gsuit :ably connectedin electricalcircuit with thefsoleneid. When the switch is closedend .the .solenoid energized, the valve is shifted .to .its upper position, .as shown Figs. l andi, Whenithe switch is open andthe solenoid .deenergized, the valve Vreturns by gravity or equivalent `.means izo .the lower position, shown in Fig. 2.

The pressure .relieving valve .means 204 .comprises 'a cylindrical valve r320 reciprocable `in .a bore 32|. The valve is formed intermediate its ends `with .a Wide, annular recess e322 and Yis formed .onether side -of .the `recess vwith v.narrow recesses 323 and -324 equally .spacedirom the in.. terniediate, Wide recesses Extending longitudinally of the vvalve --is a passage 325 opening ythrough the right hand end of the valve, as viewed .inFig l, and .communicating with this .longitudinal passage through radial ports 32.6 and 321, respectively, .are the recesses `323 and V324. The valve is constantly urged to the left,as viewed in Fig. 1 .by a compression spring. 328 Where it strikes .a boss 329 to leave an annular pass-age, the .fluid Within which .mayat -a-lltimes act on the end of the valve.

The valve here .is provided with .a port .330 lopeningthrough the end .thereof to .the annular passage .formed .about the boss .329. Thehore is additionally .formed with .annular grooves 1332 and 333, and with an enlargementf334of the bore 32|. Opening to Vthis enlarged portion .of the bore is aport 335 communicating .through .a .conduit 336 with .the tank 205. The vvarious .recessesfgrooves and ports are .so spaced that when the valve 32-0 is shifted tothe left, as in Fig1 1 .,-'the groove 332 will be in .communication with the recessf32`2, while groove 333 will register Withthe .recess 324 and thus will be connected to the tank. When the Valveis shiteclto the right, .to the position shown in Fig. 2, this ,position .being determined by abutment of the valve with an .elongated boss 331, grooves 332 and 333 will be 'bridged .by -the recess 32.2. n this circuit `-arrangement, .recess Y323 serves merely-as a tra-p for leakage uid. f v Y These valve means control thesupply or exhaust oi control iluidfrom the bore TriBand also V.control the source of the charging. duid supplied tothe cylinder |45. To that end, the changeover valve means is interposed 'between the conduits 214 and v215 leading to theport |13 with the-.conduit .214 connected to the .groove 3|2 and the conduit '215 connected to the groove 3'l'3, .Groovsl308 is connected tothe conduit 281 leading from the pressure directing valve means 20|, while groove 309 is by a conduit 340 connected to the'left "hand end ofzthe cylinder |45. .It will be seen 'thatthe charging fluid supplied to the cylinder |45 from 'the pressure directing :valve means 20| istaken directly from the closedvtransmission circuit during automatic control and thus'w'ill .transmit to the piston r|44 the .surge pressure which appears during changejfrorn traverse to feed,'or in areversal in direction ofoperaticn bythe transmission .of the table or support driven thereby. The

' changeover valve means also makespossible 'the supply of .a uniform .charging pressure from the pressure reducing valve meansl .during manual control. To .that end .groove 3|0 of valve 203 is by a conduit34| connecte'dtothe chargingpressure conduit 23| leading .from-.valve means 200.. This same pressure .is .utilized V.to shift the .valve 320.1;0 the right .and to that .end groove 3|=|..is .connected to-,port 330 .by a-shor-t conduit 342.

The valve means 2.04 is interposed betweenfthe conduits 21| and 212 with the Yconduit V21|-,conlnected to the groove 333. The hydraulic system is completed by an enlarged passage 345 connected by a conduit 346 to tank, Thebore |8|` of the main valve means |19 aswell as one end of the cylinders |42 and |46 opento this large passage 345. v

Having described the hydraulic system, `the operation thereof for certain typical and exemplary conditions will be described, inorder that the invention may be better understood and the functions and operations of the various control means and valves better correlated. Let it be assumed, therefore, that the prime mover is driving the pumps and that the system is in neutral, that is, with the valve |89 of the main control valve means |19 in its intermediate or 'neutral position shown in Fig. l. Let it also be assumed that, all of the other valves-are in the positions shown in Fig. l, particularly that the valve means 202 is in its deenergized position. Under these conditions, charging fluid is supplied to the cylinder |45 from the pressure reducing valve means 200 through conduit 23|, conduit 34|, grooves 3H] and 309 now bridged by recess 303 of valve 339, and conduit 340. Piston |44 will thus be shifted to the right and through lever |59 and plunger |58 return pistons 4| and |41- to their neutral,

position. As a consequence, the wobbler device 29 of the main pump P will be in neutral position, that is, at right angles to the shaft 30 so that no discharge of fluid will take place, while the wobbler device 39 `of the motor M will `be given its maximum tilt to give the motor M its maximum capacity. The shunt valve means 202 will connect the conduits 251 and 258 so that, should there be a slight displacement from the pump P, the fluid would merely circulate through the pump and not be supplied to the motor to cause a creeping of the transmission. Makeup fluid as well as control fluid will continue to be pumped by the makeup pump 10, and this will discharge to the transmission circuit and hence to the conduits 251 and 258. This makeup fluid is permitted to discharge to tank through the passage -255, orice 256, groove 25|, annular recess -241l and radial ports 248 to the longitudinal passage 249 of the valve 243. Control fluid is supplied to the longitudinal passage |31 of the main control valve through conduits 2| 0 and 2|2, groove |93, recess |39, and the radial passage leading Yfrom the recess to the passage |81. From the passage |81 control fluid issupplied through recess |90-, annular groove |96, and conduit 219 .to the port 269 of cylinder 85 adjusting the planetary gearing to feed rate of operation of the transmission, and through conduit 214 which now, however, is blocked by valve 309. Control fluid is alsotl supplied to the conduit 21! which now, however, is blocked by the valve 329.

To condition the system for operation either under'hydraulic control or under direct manual control, switch 269 is closed to energize solenoid 259 and thus shift valve 243 upwardlyto vthe position shown in Fig. 2. conduits 251 and 258 are no longer interconnected but are both blocked, thus rendering the transmission circuit ready for operation. Ifthe system is to be controlled by the main valve means |19, the switch 3|1 is opened to'deenergize the solenoid 3| 9 and'thus permit the valve 399 to move downwardly to the position shown in Fig. 2. As a result grooves 3| 2 and 3|3 will now be bridged by the recess 394 and conduits 214 and 215 will thus be interconnected'.A At the same In this position'the time grooves 308 and309 will be bridged bythe recess 302' connecting the conduit 340 to the conduit 281 so as to supply the cylinder with charging iluid from the-transmission circuit as distinguished from charging fluid taken from the pressure reducing valve. Grooves 3|0 and' 3|| will now also be bridged by the recess 393 and fluid under pressure Will thus be supplied tothe left hand end of the bore 32| causing a shift of the valve 320 to itsright position. Such a shift of the valve 320 will temporarily connect conduits 21| and 212 through a bridging .of grooves 332and 333 by recess 322.

'The valve |89 may now to shifted to any one of its .four positions to obtain feed or traverse rate of operation of the transmission in either a forward or a reverse direction. Initial shift of the valve is manual with subsequent shifts to obtain a predetermined cycle of operation, either manually or by means of dogs on the supportl as is the conventional practice. Let it be assumed, for purposes Aof this disclosure, that the valve |80 is shifted one step to the left so as to take its feed right position shown in Fig. 2. y As a result, control fluid is now supplied from the longitudinal passage |81 of the main valve through recess |89 to groove |92 and thence through conduit 265 to the cylinder |42. This will shift pistonY |4| to the right and thus through the lever |9 tilt the wobbler device 29 of the pump. Such shift of the piston |4| to the' right also shifts plunger |58 tothe right, and thus through the lever |59 shifts pistonA |44 to the left wh'ich in turn, through thelever |30 and associated mechanism, 'reduces somewhat the tilt of the wobbler device 39 of the motor M. At the same time, cylinder |46 is connected to tank through conduit 266, groove |94, recess |85, longitudinal passage |82, .passage 345, and conduit 346. Port 213, opening to the bore |65 intermediate the plunger |58 and th'e piston |56, also is now connected to tank through conduit 212, grooves 333 and 332 now bridged by Yrecess 322, conduit 21|, groove |9|, recess |84, longitudinal passage |82 and thence to tank, as already described. Also connected to tank is port 268 of cylinder 85, permitting shift of the piston 63 in a direction to condition the planetary gearing for feed rate of operation. This connection totank is through the conduit 261, groove |95, recess and thence through passage |82 to tank. Control 4fluid is supplied to the port 269 of the planetary gearing control means through recess |99 and conduit 210 to effect the shift just mentioned as made f possible by the exhaust' of iluid from th'e other end of the cylinder. Pressure fluid is also supplied from the conduit 210 through the conduit 214 and the conduit 215, which are now interconnected by a bridging of the grooves 3|2 and` 3|3 by the recess 334 of the changeover valve to port |13. Inasmuch as port 213 is now connected to tank through conduit 212, groove 333, recess 322, groove 332, conduit 21|, groove 9| and recess |84 to the longitudinal passage |82 in the valve |80, the fluid supplied to the right hand end of the piston |66 will cause the same to be shifted to the position shown in Fig. 2 and thus to determine the position of the plunger |58, which in turn determines the positions of the wobbler devices and hence the rate of operation of the transmission. Control fluid is also supplied from the conduit 265 through conduit 216 rto 'port 211, while the opposite end of th'e bore 218 lis through conduits 280 and 296, groove |94, and recess |85 connected to the longitudinal passage |82 8 assenso :and :thus :to tank.y .'Thewalve 2.19 will -thus 'The @shifted to its left position,v I'as "viewed in Fig. '2, appropriately :connecting conduit 281 to the low pressure for makeup side .of the transmission ciricuit. already described, this will :subject the :piston 1h14 to Vrtlfie'temporaril-y vincreased surge :pressureiinthe transmission circuit, occurring in 'a changefrom traverse .to feed or during reversal,

lso :as to assurethat the plunger |58 will follow .the'fmovement's of the plungers |-4=| or |4'|.

Should now the .valve -|8|l be shiftedmanually or'by dogs another step tothe left'to'its traverse right position, .the system `would operate at a :traverse rate-of speed. YThis .position :ofthe main valve means |19 is .sh-own infl'ig. 3fand,.1from;a l

erse operation. 'Io that end, conduit 261 :isf

through -groove |95 and recess |99 connected to the :control fluidypassage |81 of vthe main valve, while conduit 270 'is now through .recess |86 connected to the longitudinal ypassagel |82 'and thus to tank. With 'conduit 21|) connected totank .as justdescribed, -the right hand end of bore |65 also will be connected to tankfth'us permitting piston 66 to move :to Tits extreme right vposition under the Yinfluenceof 'the Ipiston |4I.V Therewill thus be given to the pump wobbler device .29the s. I

maximum angular position, While the .motor wobbler Adevice -39 will be given the minimum angular position so las to obtain the maximum rate of operation of .the transmission itself. 'It .is rbelieved apparent that the operation of th'e system to the other feed or traverse positionwill beithe same except, ofcourse, that the transmission andthe support `will be driven 'in the opposite direction.

Should .it be desired vto place the system under i the direct manual control -of van operator .instead Y of under the control of the main valve means |19, this 'may be done by returning the valve |89 to its neutral position, shown in'Fig. .1, and by energizingthe solenoidB 6 so asto shift thevalve '300 'toits' upper position, as s'ho'wnfin Fig. i. '.Such positioning of the valve |85 in neutral will 'rst ofall connect both cylinders v|112 and 5h46 to -tank. These connections, respectively, include vconduit 4265,-groove |92, recess |84, and.longitudinalpas i sage |82, andconduit 26B, groove il'94, recess 35, and longitudinal passage |82. Likewise, bothzends of ethebore 278 of the pressure :directing vvalve means 25| are vconnected to'tank,'this1beingef fectedthrough conduits 216 and 28d connected, respectively, to conduits `i265' and 2556. Shift of the-valve i390 `first of all connects the left hand end of bore 32| .of the valvemeans 264 to tank through conduit 342, groove 3|.|, radial :ports 38S, and longitudinal passage 301|, permitting the spring 328 `to return the valveto its left position, as tshown in Fig. `l.` Thi-s shift of the valve l321i) breaks the connection `4`Abetween; conduits 2i! and 272 and ccnnectsconduit 212 to'tarik through recess 324, radial port Y321, 'longitudinal passage 325, port 335 and cfmduit.'tl.` 4The shift 0f the valve 300 has already 'broken the connection betweencondui-ts 274 and2l5 andhas connected VconduitZllii ,to A'tank through groove jwhich now is fopen directly .to the port 3|.1i.fThus,with

pressure V-reli'evzved from `fthe `bore 165, boi-,hbotWeenIthe--plunger A|58 and `the piston lldandbe- -liind the piston 216B ias lwell as in the cylinders '|42 and lilfthe operatori may nowmanually atljus't fthe transmission for `operation in -either direction and'at any desired rate *within the Vfeed range by rotating the shaft `|5| Vas by means of handle |51. This shift of the` valve 39B to the vposition shown in Figs. 1 and -4 also reestablis'hed connection between the conduits AZilli) and 331 through bridging of grooves3l9 and -3 @by recess -303. The cylinder |45 is now connected ztothe pressure-reducing 'valve means v202), and the increa'sed --pressure resulting as Vthe piston '1M is shifted to the left will act on the right 'hand end of the valve 2|5 through the Vbleed passage 228, and will shift the same to the left until recess 218 registers with groove 225 (see'Fig. yo). The excess fluid may then flow totankthrough radial port 2|9 and longitudinal'passage 220. Thus it will Vbe seen that the feed control device is ren dered inoperative and the wobbler devices '29 vand 39 may be adjusted Vfor operation atany desired feed rate Within the range of the transmission by manual operation of the handle V|15|,since this handle is mechanically connected to the wobblers by the intervening connecting parts 5|,"I 5l), 145|,

||9and |I5, and |58, |59, |44, |30 and |26.

Finally, should it be desired not merely'tocontrol the system directlyvbut to actually move the support manually, `the solenoid 259 is deenergized to permit the valve means 292 to return to 'posi'- tion shown in Fig. '1 -wherein the intake and dis charge ports of the main pump P are short circuited and wherein groove 25| now is in registry with recess 241 to be connected with tanklthrough radial ports '248 and longitudinal passage 2259. The prime mover also is preferably stopped. As the support is moved, 'the transmission is, of course, actuated and will force the fluid in the transmission circuit through the orifice 256 and thus discharge to tank. After one complete revolution of the Vmotor M `and pump P, all of the iiuid in the transmission circuit will have 'been exhausted, thus obviating the necessity of constantly forcing the fluidthrough the transmission and thereby making the movement of the y'support very easy. f

It is kbelieved that the foregoing description and recapitulation of the operation, taken in connection With .the drawings, Will render they invention completely and readily understandable. It is also believed that we vhave perfected unique and improved rneans for providing direct manual control of the direction and rate of operation vof the transmission, l'whilealso providing for automatic or hydraulic control through amain valvemeans` When the .system is arranged for automatic operation at a feed speed determined bythe wfeed control piston |66 and its adjusting screw |63, itmay be changed over .to manual .operation and controlled Vby handle |5|.., .after which, when it is changed back .to automatic operation the original feed speedis again obtained since there .has been ,no change in the Vadjustmentof .screw |59` Under manual .control the rate of .feed `is proportional to the distance the handle |5l is moved away from its neutral position-of Fig. 1.

VOther features and advantages arealso believed apparent, particularly the provision for discharge of uid Ifromthe 'transmission `circuit when it is desired to move the support `by hand, as well as the provision in a pressure reducing -va'lve of means for permitting escape Aof a portion-of the fluid to enable uid to be relieved from-the cylinder |45.

We claim as our invention:

1. In a system for motivating a support, motivating means for driving the support, means controlling the motivating means to drive the support at predetermined rates within the range oi the motivating means, power operated means for actuating said control means to obtain said predetermined rates, and manual means alternatively operable to actuate said control means to obtain movement of the support at any rate throughout the range without limitation to the predetermined rates.

2. In a system for motivating a support, motivating means for driving the support, said means being adjustable to operate throughout a range of rates, power operated means controlling` the motivating means to operate at a predetermined rate within the range, and alternatively operable manual means for actuating said control means to obtain operation at any rate within the range Without limitation to theset rates and without disturbing the setting Vof the power operated 'means for subsequent return thereby to said set rates.

3. In a hydraulic` system, a transmission'adjustable to operate over a range of feed rates, control means for the transmission causing the transmissionv to operate at a predetermined feed rate, power operated means for actuating said control means, and manually voperable means optionally effective on said control means for obtaining operation of the transmission at any desired feed rate within the range, said manually operable means including ahandle shiftable from a neutral position to dilferent feed'rate positions with the rate f feed determined by the extent of shift and the direction of feed by the direction of shift of the handle from neutral.

4. In a system for motivating a support, motivating means for driving the support, said means jbeing adjustable to operate throughout a range of rates, control means governing adjustment of said vmotivating means, pilot means governing said control means to cause operation of said motivating means at set rates, manually operable means directly actuating said control means to lobtain operation at any rate ,within the range without limitation to the set rates, and means for rendering the pilot means ineffective when the manually operable means directly kactuate th control means. l 5. In a system for motivating a support, motivating means for driving the support, said means being adjustable tooperate throughout a'range of rates, means for effecting adjustment of said motivating means, manual means associated with said adjustment effecting means for direct actuation thereof, presettable means operable when supplied with an actuating medium to limit adjustment of said motivating means to a set rate, Aand means exercising control over said adjustyment effecting means and said presettable means to cause operation of the motivating means Vat ated means for-effecting adjustment of said motivating means; presettable meansoperable when supplied with an actuating medium to limitadjustment of said. motivating 'means to a set-rate, and means exercising control over saidad'justment effecting means and said presettable means to causer operation of the motivating means at set rate or'to free said adjustment effecting means and said presettable means for Vdirect manual actuation of said adjustment effecting means to' obtain any( desiredrate -withinthe range of rates. l i '7. In a system for motivating `a support, motivating means for driving the'support',saidmeans being adjustable to operate throughout a range of rates, shiftable means for' effecting 4adjustment ofv said motivating: means with the extent of movement of said shiftable means determining the rate of operation lofthe motivating means, hydraulically actuated presettable means voperable when supplied with fluid under vpre'ssure'to constitute a stop vlimiting the shift of said^sl1ift able means to the preset rate, manual means associated with'- said shiftable means for rdirect actuation thereof, and meansrv controlling the supply or exhaust of fluid to said presettable means to effect operationv of the motivating means at the preset rate or to permit direct manual operation of s'aidrshiftablel means to 'any-dlsired position without limitation by the presetta ble means.

v8.? In a system' for motivating a supportjmotivating means for driving the support, said means being adjustable to operate throughout afrange of rates and in forward o'r reverse directionyhydraulically operated means causing operationof the motivating means in'either direction andat set rates, manual means associated with said hydraulically operated means form'anual'actuation thereof, and means relieving the hydrauliepre'slsure inthe hydraulically operated meansv to -perflmit direct manual adjustment for operation of the motivating means ineither direction and at any rate Within the range of the motivating means. f i

9. In a system for motivating a support,'mcti vating means for driving the support, said means being adjustable to operate .throughout a range of rates and in either forwardv or reversedirection, a piston and cylinder device shiftable in either-direction from a'lneutral position to determine the directionof operation of the motivating means and determining the rate of operation 'of the motivating means'by the extent ofy shiftfrom neutral position, manual means associated Awith said piston and cylinder device'fo'r direct manual shifting thereof, a hydraulically actuated device forming when actuated a limit/stop for said piston and lcylinder device determining the extentof shift of said 'piston and cylinder-deviceand including an adjustable means for` determining' the actuated position of the hydraulically actuated device, and a hydraulicv control circuitV for said piston and cylinder device and said hydraulically actuated device including a main control valv'e exercising control to obtain operationof the ,mo-.- `tivating means at set rates, and changeover-valve means rendering said hydraulically actuate'dadel `vice inoperative to permit. manual shift ofthe piston andcylinder device in eitherdirection Vand to any desired extent. I 1 10. In ahydraulic system', a transmission oper,- able at different rates andrinfforward; and-jre,- verse directions and a control-,system for govern- -ing the operation of the.transmssionoinprising a v-pistonandzy cylinder.V device, -shi-ftable in opposite ndirections from. awneutralL-position to determine the-direction-of operation-ofthe transmission and .determining ,the-fate. -ofaoperation of theV A:trans- Ymissieirloythefextent-:ofI shift from neutral position,- .a second pistonA and'- cylinden. device `includ- .;ingfadjustable means-for limiting- :theI movement vof; thev :piston offsaid :second :dev-ice, saidzpiston @when actuatedby tha-supply ofdluid pressure to theeyice acting'as ai-imit stop-'controlling the eexteizitfof.v shiftofesaid';Qrstppistoniandt cyiinder device, manually operable means associated'with saidf ilrst1.pistoni and-.,cylinder .devi-ee. for direct manuals .operationithereofgfa main: control -valve .means. means iorrsupplying controluidthereto, afcircuit connectiozr-fromisaid :main valve means =.to.said-.rstmentioned pistoneand cylinder. device, :a mircuiticonnection .from said maint-valve :means tsaidsecondfpistorra and cylindersdevice,and a valve means interposed-inthe last mentionedcir- L..cuit.connection-.and operable toplace said second Y pistonarici .cylinderf tde-vice- .funderf the control. -of

' valve meander-to disconnect the same therefrom Y.and relieve thesecond; piston .andeylinder zdevice. .of allduid pressure. x

f 11..:In.a hydraulic zsystem, a transmissioniopery,allientdifferent rates/and .in forward and reverse directionsand .accu-trol system for governing :the ,operation lof-.thetransmissiorn .comprisinga piston and., ,cylinder :device rshiftable ini-oppositedirections from a neutral position to determinethe-di- .rection-,otioperatiorr offthe transmission and. de- ,.terminingtherate offopextatiomof the .transmis-- sioncby theiextent' of, shift Vfrom :neutrai' position, ia-second 1pistonsand-cylinder dey-ice including 'adlinstable` means for: limiting the movement 'fof :the piston of.said,secendtdevice;said piston when facmatedv by itleesupply of fluidepressurefto tlf-ie de- -vce-.actingas .ajlimit lstopcontrolling -1 the extent ,offshiIt-oig'said irst pistoni and :cylinder-device, manually separable .meaxisf1-assoeiated-.fwith :said rstfj-pistonfandicylindendevice*for-:direct manual operation; thereof., E fa main contro1`- valve imeans, `lmeansfor supplyingccon-troluidftheretoya -cir- .said,-.rst mentioned ,flpiston and` cylinder .dei/Tice, fmeans :alternatively miserable to f 'place :fthe secondr pistonnndfcylindemdeviceunder-the con-- troltofisaid-main valvefmeanszto obtain-ioperation :of thetransmission at-setrates or toremovesaid f .secondpistcnf-and cylinder device: from theeontrol of? said; main valve means andfconnect the 'same .toitank-:to Apermitf.manual.operation cfs-said first :mentioned: .pistcnand :cylinder`` means :to -iany ex- .tent desired.` Y

12; .-Infaehydranlic systeme: transmissioneoperfatdiierentrates and-.inrforwardandreverse directions, anda :control .system 1Aiorgoverning the ioperation of rthet-ransmissione-cornprisinga first i piston sand foylmder-idevice withfth-e piston shift-- ableinopposite directionsrfroma :neutral position :to 'determine :fthe @direction of operation of y.the itransmissionzand inetermining A:the frate-of :oper- 'satimzof'the tziaansmission':by:theextent-offshift .trbm neutral position, amylindierfzfornnngimeans,

ariplungersreciprocable 'finfonefendtof 1 the f cylinder no ftormed-mndlahuttedfbyfsaid :pistonandicyliniti'ng` :the movement :of-irsaid fpistonstoward :said

plunger, vsaid piston throughssazid qihingerfacting *as* .sa stop limiting 'the sshitt l of :saidrst piston -andcylinderzdeyiceg manually operabie means. associated-with said; rstzpistoxr and cylinder: device `foredirlect:rrianual.operation .thereogia :main acorr- `cuit connection from said main valve meansxto S45 trol valve means,` vmeansy -rorsupplying-control fluid to said valve means, a circuit connection from said valve means to said rstfmentionedpiston andcylinder-device, a circuit connection from said .main valve means to'said cylinder 4between saidplunger and said piston, and a valve means interposedv in the last-mentioned circuit connection and operable to. complete the connection from pricing` afirst piston'v and y cylinder.l device v:with

.the piston; shiitablel in. opposite .direc-tions .from a' neutialY `positonfto. deter-mine the direction-g of :operation `of-V the transmission and determi-ning therate of .operation of the-transmission by. :the

extent of shift from neutral position, .a cylinder forming'f means, a; plunger reciprocable .intone endiof the cylinderso formed and .abuttedbyrsaid fpistony and Icylinder device, --a piston reciprocahle .fin the other'` end of the cylinder,so-,formed,..ad

justable means limiting the movement oisaid A,pistonitoward. said plungenlsaid. piston through said: plunger` acting as laston limiting theshift ,-.of said rst .piston -andcylinder -devicet manually operable means associatedlwith saidrst piston and cylinder device. for direct manual Yoperation thereof,- amain control valve means, means for supplyngcontrol -fluidtosaidvalve means, la circuit .connection rfrom said Valve means to.. said iirst mentioned pistonandcylinder device, acircuit connectionfrom said main valvevmeansto Ysa-idrcylinder between said plunger and said. piston, .a .valve means interposed -in the last mentionedv .circuit `connection and :operable to'- .complete the connection from thefmainrvalve-means ,to the cylinder orto disrupt-tnewconnection .and relievev the space. zbetween thev piston. and-plunger .of-:all fluid pressure, and valve means controlling the supply of .nuid .to V.the .end :of said cylinder containing -v-the piston also controlling .said i last Vment-ioned-valve means.

i14.. In 7.a hydraulic system, ,a transmissionfoperable at ydifferentratcsand-gin `forwardand reverse directions `and a control .system f for. governing the operation of the transmission. comprising .a Apairfof Apiston .and cylinder devices, rack` teeth on the pistons, a pinion meshing .with therack teeth to interconnect the pistons, .anfoperating lever rigid with the-piniontor. manually shifting the pistons, `means including aplunger V.common vto'looth pistons `connected with the-'transmission .to cause the transmission fto operate in one .direction or the'other-dependent upon thedirection of shi-ftci the pistons .and to operateat .arrete determined .by .the extent of shift of the-pistons, athird piston and .cylinder deviceincluding Aan adjustable screw determining shift of the piston lof the last mentioned` device in, a Ydirection vtoward said plunger to form a limit stopfo'r shift'oftlie plunger 'by either 'of said'pair ofi piston and cyl.- inder devices, and a `hydraulic control circuit in 'lcl-uding said piston and `cylinderdevices, a vv-niain A--valve having a neutral position relieving bothf the #pair of" piston and cylinder devices of Iiiuid fpressure and a'positioni onileither .side of neutral directing uid under pressure to one or thelother Jof said "pair 'of' piston and cylinderdevices, .said valve' in :all three positions vv.directing :ui'd 'under :pressure 'to` said :third :piston andrcylinderifde- Nice; and .auxiliary-valve meanspperablelinfone assenso position to permit a supply of fluid under pressure from said main valve means to said third piston and cylinder device and operable in anotherposition to interrupt-the supply of pressure fiuid and to relieve said'third piston and cylinder device ofiall fluid under pressure to permit ready manual operation of said pair of piston and cylinder devices when said main Valve means is in neutral.

15. In a system for motivating a support, a motivating means operable at different rates and in forward and reverse directions, and a control means for the motivating means comprising a shiftable member having a neutral position, means interconnecting said member with the motivating means to determine the direction of operation thereof by the direction of shift of .the member from neutral position and the rate of operation by the extent of shift from neutral position, hydraulically actuable means for shifting said member, a manual means associated with said member for optional manual shift thereof, a main control valve means governing shift of said member hydraulically, means adjustable to limit the extent of movement of said shiftable member hydraulically, and means perable selectively to render said last mentioned means effective to limit the shift of said shiftable member when the latter is under the control of said main valve means or to render said limit means ineffective and permit any desired Eshift of said shiftable member by said manual means Without disturbing the adjustment of said limit means. 4

16. In a hydraulic system, a transmission operable at different rates and in forward and reverse directions, and a control system for governing the operation of the transmission comprising a first and a second piston and cylinder device, means interconnecting saiddevicesy manual means rigid with said interconnecting means for direct manual actuation of said piston and cylinder devices, means including a third piston and cylinder device acting in opposition to said first and second devices associating said first and second devices With said transmission causing the direction of shift of the devices to determine the direction of operation of the transmission and the extent of shift of said iirst and second devices tc determine the rate of operation of the transmission, a fourth piston and cylinder device operable when supplied with fluid under pressure to provide an adjustable stop limiting the extent of movement of said first and second devices, and a control circuit including said piston and cylinder devices and also including a source of control fluid for said first, second and fourth devices, a main valve means governing the supply of control fiuid to said last named devices, a pair of sources of actuating fiuid for said third piston and cylinder device, and valve means alternatively connecting said third piston and cylinder device with one or the other of said pair of sources and alternatively connecting said fourth piston and cylinder device to said main valve means or to tank.

17. In a hydraulic system, a hydraulic transmission operable at different rates and in forward and reverse directions and having a closed Working circuit, and a control system for governing the operation of the transmission comprising a first and a second piston and cylinder device, means interconnecting said devices, manual means rigid with said interconnecting means for direct manual actuation of said piston and cylinder devices, means includinga third piston and cylinderldevice acting in oppositionito said rst and second devices associating said first and second devices With said transmission causing the directionof shift of theV devices to determine the direction of operation of *the -transmission and the extent ofshift-of said .firstand second devices to determine the rate of operation of the transmission, a fourth piston and cylinder device operable When supplied with uid under pressure to provide an adjustable stop limiting the extent of movement of said first and second devices, and a control circuit including said piston and cylinder devices and also including a source of control fluid for said first, second and fourth devices, a main Valve means governing the supply of control iiuid to said last named devices, pressure directing valve means governed by said main valve means operable to provide a connection to the low pressure side of the working circuit of the transmission, pressure reducing valve means connected directly to the source of control fiuid for said first and second piston and cylinder devices, and a valve means operable in a first position to place said fourth piston and cylinder device under the control of said main valve means and in that position to connect said third piston` and cylinder device to said pressure directing valve means, and operable in a second position to 'remove said fourth piston and cylinder device from the control of said main valve means and in that position to connect said third piston and cylinder device to said pressure reducing valve means.

18. In a hydraulic system, a hydraulic .transmission operable at different rates and in forward and reverse directions and having a closed Working circuit, and a control system for governing the operation of the transmission comprising a rst and a second piston and cylinder device, means interconnecting said devices, manual means rigid With said interconnecting means for direct manual actuation of said piston and cylinder devices, means including a third piston and cylinder device acting in opposition to said rst and second devices associating said first and s'econd devices with said transmission causing the direction of shift of the devices to determine the direction of operation of the transmission and the extent of shift of said first and second devices to determine the rate of operation of the transmission, a fourth piston and cylinder device operable When supplied with fluid under pressure to provide an adjustable stop limiting the extent of movement of said first and second devices, and a control circuit including said piston and cylinder devices and also including a source of control fluid for said first, second and fourth devices, a main valve means governing the supply of control uid to said last named devices, pressure directing valve means governed by said main valve means operable to provide a connection to the low pressure side of the working oircuit of the transmission, pressure reducing valve means connected directly to the source of control fluid for said first and second piston and cylinder devices, and a valve means operable in a first position to place said fourth piston and cylinder device under the control of said main valve:

means and in that position to connect said third piston and cylinder device to said pressure directing valve means, and operable in a second position to remove said fourth piston and cylinder device from the control of said main valve means and relieve said fourth piston and cylin-

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