US2375737A - Crank grinding machine - Google Patents

Description

y 5- l H. A. SILVEN 2,375,737

CRANK GRINDING MACHIINE Filed Sept. 11, 1944 3 Sheets-Sheet l Fig, 1 9 "75 I 46 grwvwto b HERBERT A. 51mm y H. A. SlLVEN CRANK GRINDING MACHINE Filed Sept. 11, 1944 3 Sheets-Sheet 2 F 2 q 12o A Kg 1 o e v w Flq. 322 1 2 m HERBERT A. SILVEN May s, 1945.

H. AUSILVENl CRANK GRINDING MACHINE Filed Sept 11, 1944 3 Sheets-Sheet 3 gllll/Wl/Wfll HERBERT A. 51:. van

and arrangements of Patented May 8, 1945 UNITED STATES ,PATENT OFFICE CRANK GRINDING MACHINE Herbert A. Silven, Worcester, Mass, assignor to Norton Company, W ration of Massachuse orcester, Mass, a corpotts I Application September 11, 1944, Serial No. 553,573

Claims.

This invention relates to grinding machines, and more particularly to a double head crankpin grinding machine.

One object of the invention is to. provide a simple and thoroughly practical, readily controllable crankpin grinding machine. Another observes to control the'various movements of the grinding machine.

steadyrest shoes. tion is. to provide a crankpin grinding machine with a single lever control having a. remote controlsuch as an electrically controlled change speed mechanism means of a manually operable limit switch'on' pendent valves for controlling each of said mechanisms, all of which are actuated by a single control lever. Another object of the invention is to connectone of said valves so that when the machine parts are in an idle position, a balanced pressure relief valve will be actuated to drop the operating pressure in the hydraulic system to zero. Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the tea tures of construction, combinations of elements,

partsas will be exemplified in the structure to be hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings, in which is shown one, of various possible embodiments of the mechanical features ofthis invention,

Fig. lis a diagrammatic illustration of the hydraulic system and t the movements of the variousmachine parts; I

Another object of the invene electric wirlng for controlling 2 is a fragmentary front elevation of a portion of the front of the machineon an enlarged scale, showing the main control lever and associated parts;

Fig. 3 is a fragmentary end elevation, partly in section, of the parts shown in Fig. 2; i Fig. 4 is a horizontal sectional view, taken approximately on thevline 44 of Fig. 3, showing the guard for restricting the movementof the main control lever;

Fig. 5 is a fragmentary detail view, showing the connection between the main control; lever and the table control valve;

Fig. 6 is a fragmentarydetail view, showing the main control lever together with connections between the control lever and the wheel slide control valve, the table auxiliary fvalve for controlling the hydraulic steadyrest; i

Fig. 7 is a vertical sectional view, on an enlarged scale, of the balanced-pressure type re-, lief valve; i

Fig. 8 is a vertical sectional view, on an enlarged scale, through the wheel slide and table control valves; l

Fig. 9 is a sectional view through the auxiliary control valve Which controls the steadyrest and also serves as a venting valve for the balanced pressure relief valve;

Fig. 10 is a fragmentary plan view showing the pivot stud for the main.

connection between the control lever and the shaft for actuating the auxiliary control valve {and Fig. 11 illustrates a modification of the solenoid actuated valve in which the valve is normally.

' shown.

A longitudinally movable work supporting table I5 is arranged to slide longitudinally relative,

to the base I ll on the usual V-way l6 and .flat way (not shown). The table l5 serves as a sup The wheel slide ll may be moved transversely to feed the grinding wheel l2 toward orfrom thework piecemanually by means of a nut and screw mechanism comprising a rotatable feed control valve, and: the;

screw 20 which meshes with a half nut 2| depending from the underside of the wheel slide I The feed screw may be operatively connected with a hand wheel (not shown) which is rotatably mounted on theiront of the machine base in a manner substantially the same as that shown in my prior U. S. patent above referred to.

In order that the grinding wheel l2 may be moved rapidly toward and from the work piece to be ground, it is desirable to provide a fluid pressure mechanism which supplements the nut and screw feed and serves rapidly to move the grinding Wheel toward and from the work. As illustrated in the drawings, a piston rod 22 is operatively connected with the rear end of the feed screw 20. The piston rod 22 is connected to a piston 23 which is slidably mounted within a cylinder 24. The cylinder 24 is fixedly mounted relative to the base Hi. When fluid under pressure is admitted through a pipe 25 into a cylinder chamber 26, the piston 23 will be moved toward the left (Fig. 1). During this movement, fluid within a chamber 21 at the left-hand end of the cylinder 24 will be exhausted through a pipe 28. The control of fluid under pressure to the feed mechanism above described will be explained in detail hereinafter.

The work. table I is preferably arranged so that it may be traversed longitudinally by means of a hydraulically operated mechanism comprising a cylinder 36 which is fixed relative to the base l0. vided within the cylinder 30 having a double end piston rod 32 which extends through the opposite end caps on the cylinder 30. The opposite ends of the piston rod 32 are connected by brackets 33 and 64 respectively depending from the under side-of the table I5. When fluid under pressure is admitted through a pipe 35 into a cylinder chamber 36, the piston 3| will be caused to move-toward the right (Fig. l) to transmit a corresponding movement to the table l5. During the movement of the piston 3| toward the right, fluid within a cylinder chamber 31 willbe exhausted through a pipe 38. Similarly, when fluid under pressure is passed through the pipe 38 into the cylinder chamber table l5 will be moved in a direction toward the left (Fig. l). The mechanism for controlling the admission to and exhaust of fluid from the cylinder 36 will be described hereinafter.

, Hydraulic control When grinding the crankplns on a crankshaft, it is necessary that the wheel be moved through a considerable distance in order that the table may be traversed to position successive pins in operative relation with the grinding wheel. It is highly desirable to interlock the table traverse mechanism, the wheel feeding mechanism, and the steadyrest actuating mechanism so that the table cannot be traversed when the wheel and the steadyrest are moving toward or from the work, and so that the wheel cannot be fed toward the work or the steadyrest moved into an operative position during the table traversing movement to position successive crankpins in operative relation with the grinding wheel. In the preferred construction, a pair of control valves (Figs. 1 and 8) are provided, oneof which serves to A slidably mounted piston 3| is pro-.

31, the piston 3| and the control the admission to and exhaust of fluid from the table traverse cylinder 30 so that either a fast or a slow traverse may be obtained in either direction, and the other of which serves to control As illustrated in the drawings, a control valve 4|! is provided for controlling the admission of fluid to the feed cylinder 24. The control valve 40' i preferably a piston type control-valve comprising a valve stem 4| having formed integrally therewith valve pistons 42, 43, 44 and 45,

A fluid reservoir 46 is provided either in the base of the machine or is positioned adjacent thereto. A motor driven fluid pressure pump 41 is provided to draw fluid through a pipe 48 from the reservoir 46 and to pass fluid under pressure through apipe 49 into a valve chamber located between the valve pistons43 and 44.

A control valve is provided for controlling the longitudinal traversing movement of the work table I5. This valve 'is preferably a piston type valve comprising a valve stem 56 having formed table, both valves being positioned in a neutral or central position.

An exhaust pipe is provided for controlling the exhaust of fluid from the'valve 55 when the table I5 is traversing at a normal traversing speed in one direction. 'A similar exhaust pipe 66 is provided for controlling the exhaust of fluid from the valve 55 when the table I5 is traversing at normal speed in the'opposite direction. In order to obtain a very slow, uniform speed of the table for a truing operation or to slow down the table movement just prior to engagement of the stop dogs, auxiliary exhaust pipes 61 and 68 are pro vided, each having a spectively, by means of which the speed of movement in either direction'may be readily controlled. The valves 69 and 10 are connected to a common exhaust pipe II which leads directly to the reservoir 46.

The exhaust pipes 65 and 66 are similarly conconnects with the exhaust pipe 52 so that the exhaust pipe 52 carries the entire exhaustfrom both the wheel slide control valve 4|) and the table traverse control valve 55. The exhaust pipe 52 is provided with a throttle valve 13 by means of which the exhaust of fluid from either the wheel slide control valve 46 or the table control valve 55 may be readily controlled. In order to allow a rapid positioning movement of either the grinding wheel slide II or the work table |5, a solenoid-actuated slow-down valve 15 is provided. This valve comprises a valve stem 16 having formed integrally therewith a pair of valve pistons 11 and 18. The outer end ofthe valve stem is provided with a spool-shaped member 79 which is connected by means of a pin 80 with a downwardly extending arm 8| of a bell crank lever 82. The bell crank lever 82 is pivotally mounted on a stud 83. of the bell crank lever 82 is connected by afstud 85 with a link 86 which is in turn connectedby a stud 81 with an armature 88 of a solenoid 89. In the position of the valve 15 as illustrated in Fig. l, fluid exhausting through the pipe 52 from either the wheel slide control valve 40 or the table control valve 55 may pass from the pipe 52 through a pipe 90, into a valve chamber 9| located between the valves 4|) and 55 as illuscontrol valve 69 and 16, re-

The horizontally extending arm .84.

v the valvereservoir Mi. A bushing 74 the the pipe 92 and return pistons. H and I8 of the control valve 15, and outwardly through a pipe 292 into the valve 15 serves as a stop, normally .to locate the valve pistons" and 18in an'open position. When the solenoid 89 Iisenergized; the bell crank lever 82 will move in a cot-mterclockwisc direction to shift thevalverstem FEB toward the right against the compression oflasprin-g 53 so that the valve piston =11 will close ,a port atthe end of the ex haust pipe 80 after which fluid exhausting through the pipe :52 must pass through the throttle valve 13 to slow down the movement ofeither the-wheel slide or the table, depending upon which of the mechanisms is in an .As shown in Fig. .1,

operative position. the solenoid actuated valve contmiyaclve M1 is provided for controlling the admission to exhaust steadyrest cylinder M3. The valve I8] is profs 15 is illustrated as :a normally open valve in which closing of the valve by actuation of the solenoid 89 serves to out 01f. unrestricted exhaust or :fluid and thereby slow down either the wheel slide movement. In certain grinding operations it may be desirable to provide it normally closed valve which may he opened when desired so that a slow traversing movement of thework table or a slow feeding movement of the grinding wheel slide may be speeded up when desired. .As illustrated in Fig. 1 l, of the valve 15 is illustrated in which the stop bushing 14 is eliminated and the valve pistons TI! and 128 positioned in an extreme left-hand end position so that no filuid may pass from pip dfl intopipeQl.

I-f vdesired, the valve stem 15 and valve pistons 17 and 78 may he so designed and arranged that when it is desiredto shift-from :a normallyopen to a normally closed valve, is merely necessary to remove the bushing 14 from the valve casing 15 and shift the valve stem 16 :end for end and then re-assemble into the condition illustrated in Fig. 11. The other parts of the valve and actuating mechanism therefor, .as illustrated in Fig. 11, are identical with that shown in .Fig. l, consequently the same reference numerals have been used. In the operation of the valve as illustrated in Fig. 11, during the normal movement of the table 315 or Wheel slide H, fluid exhausting from the valves 55 and 40 respectively passes through the throttlevalve 33 so as to produce a slow traversing movement of the table or .a slow feeding movement of the grinding. wheel 12. When it is desired to speed up the movement of the table or the vv'heel slide, an electric circuit is closed to energize the solenoid, 8.9 (Fig. .11) which causes the valve stem 16 to move toward the right so that the valve pistons 11 and 18 move a modified form i into .a position so thatsubstantially unrestricted exhaust of fluid maypass from the pipe .98 into to thereservoir It. Steadyrest I Asteadyrest IUD is provided comprising a pair of steadyrest shoes Ill-I and H12 which are preferably arranged'to be moved to and from anropera'tive position by means of a fluid pressure ,cylinder M3 which contains a sli-dably mounted piston 104. .The details of thesteadyltest are not considered to be .a part of the present invention, consequently they have not rbeeniillustrated in detail nor will they be described herein. This steadyrest is identical with scribed in my copending-U. 8. application Serial No. 534,241 filed May 1944, to which reterence may .be had for details of construction not tound herein l a l m. -A;pair.of pipes M5 and 1-06 areconneetedwith table '01 the that shown and :de-

l the piston HM toward the through an exhaust pipe 46. V

erahly .a piston type valve comprising .a valve stem 19. having formed therewith a plurality of valve pistons #09, Ill-l1, I all and H2; Fluid under pressmtepassing from the pressure pump 41 through the pipe flg through a pipe l 3 into a cylinder chamber H4 located between the valve pistons H0 and ill. In the positionlof the valve illustrated in Fig. fluid under pressure entering the valve chamber. H4 may pass outwardly through the :pipe 106 to cause the piston 164 to .movetow.ard the left so as to move the steadyrest shoes i111 and on into an imperative position. During movement of,

left (Fig. lhfluid Within the cylinder chamber at the left-hand end of the cylinder 103 may exhaust through the pipe me into a valvecham'ber Nil-land pass Dl-ItWaldlY H6 into the reservoir Single control lever the sleeve 124., and

rod 125. It will be readily apparent'from the the lever PM is moved to-' vvardpr from the machine "base pivot-ingabout the rod I25, the valve stem 41 to change the position :of the valve l0 so as to contro'hthe admission to and exhaust of flu-id from the 'wheel feed cylinder '24. i The lever 120 is arranged to swing in a direction parallel to :the base 10 about the stud I23 and the mechanism is so connected that the lever serves to control the position of the valve 55 to control the longitudinal movement of the table 15. The valvestem 58 is provided at its' outer end with a grooved, spool-shaped member lZB'vvhich is connected by fa M9 withthe long arm I30 of a bell crank lever 13%. The cell crankjlever i3! is provided'with a short arm 154 which, is pr'eferablyin the form ofa pin riding in a bushing 4.35mi the control lever 420. The pin 63 short arm 134 fits freely'within the bushing I35 so that the lever 1.20 maybe .moved toward and from the of fluid from the l that is, parallel with the machine base, the bell crank lever 'I3I is rocked about its pivot stud I32 to shift the valve stem'56 so as to change the position of th'e'control valve 55 so asto obtain either a fast or a slow traversing movement of the' table I5 either in a direction toward the right or toward the left, as .viewedin Fig. 1, depending upon the position of the lever I20. I

In order that the auxiliary control valve for controlling the steadyrest may be operated in the desired timed relationship with thewheel slide control valve 40 and the table control valve 55, an inter-connection is provided comprising a rotatable shaft I31 which is journalled in bearings' I30 and I39 on the front of the machine'base I (Fig. 6). hand end of the shaft I31. The arm I40 is'provided with a pin I4I which engages a spoolshaped grooved member I36 which is fixedly mounted on the end of the valve stem I08; In order to allow the pivot stud I22 to rock with the control lever as the control lever I20 is moved parallel to the machine base, a sliding connection isprovided between the'pivot' stud I22 and the shaft I31. The shaft I31 is preferably provided with a slabbed-off end portion I42 having parallel side faces which mate within a slot I43 (Fig. 10) formed in thepivot stud or shaft I22.

.It will be readily apparent from the foregoing disclosure that the ,pivot stud I22 may swing in a plane parallel to the front of the machine base relative to the shaft I 31 without becoming disconnected therefrom. When the lever I20 is moved toward or from the machine base to transmit movement of the control valve 40 to the valve stem M to initiate either a forward or a rearward feeding movement of the grinding wheel I2, a rocking motion will be transmitted through theshaft I31 and the arm. I40 to move the valve stem I08 and thus shift the auxiliary control valve I01 sothat the steadyrest I00 will be operated in timed relation with the wheel feeding movement. When the wheel is moved toward the work, atthe start of the grinding operation, the auxiliary control valve will be moved so as to admit fluid under pressure through the pipe I to move the piston I 04 into the position illustrated in Fig. 1 so that the work steadying shoes An arm is fixedly pinned to the left- I01 and I02 are moved into operative supporting engagement with a work piece.

In order that the movement of the control lever I20 may be rapidly positioned in one of several different positions to interlock the movements of the valves 40, 55 and I01 so as to control the traversing movement of the work-table I5, the feeding movement of the grinding wheel slide "I I,

the positioning of the steadyrest shoes IM and I02, and, the venting of the hydraulic system when the machine is idle, it is desirable to provide a suitable guiding member'to control the movements of the lever I20. As illustrated in Fig. 4, a guide plate I44 is mounted on the base of the machine 'I0and is provided with a crossshaped slot I45 therein which serves to restrict the movement of the control lever I20 in its movement toward and from the machine or longitudinally relative to the machine base. In the full line position of the lever I20e (Fig.4), the valves 40 and are in the position illustrated in Fig. 1, in which position the table I5 isstationary and similarly the wheel slide I I is stationary and in a rearward or inoperative position, Whenthe lever I20 is in position I20e, the auxiliary control valve I01 is in a venting position 1 so that the left or toward the right. If the lever substantially zero.

When it is desiredto start the machine, the lever I20 is moved from position I20a into posi-: tion I20b (Fig.4). The lever I20may then be shifted toward the left into position I20e or toward the right into position I20d which movements shiftthe control valve 55 so as toystart a traversing movement of the table I5 toward the I20 is shift: ed into position I20e or I201, the traversing movement of the table is slowed down due to the fact that the valve 55 has been shifted so that fluid exhausting therefrom must. pass through the throttle valve 59 orthe throttle valve 10. It will be readily apparent that Whenthe control lever I20 is moved throughtoward the left or toward the right, it cannot be shifted forwardly due to the shape of the guiding plate I44, thus preventing a wheel feeding movement during the traversing of the work table I5 to position the work piece relative to the grinding wheel I2.

Whenit is desired to cause an infeeding movement of the grinding-wheel I2 after the work iece has been positioned relative the grinding wheel, the con'trol leverI20 is shifted intoposition I209 which'movement serves toshift the Pressure relief In order to conserve power and prevent un- I due heating of the oil due to wire drawing of the oil, when the table I5 and the wheel slide I I are in inoperative positions, it is desirable that the system be so arranged that the fluid pressure will be automatically reduced substantially to zero by allowing fluid from the pressure pump 41 to pass substantia ly unrestricted back to the I ber I5I of a balanced-pressure relief valve I52.

The'relief valve I52 is of abalanced-pressure type, I

comprising a valve member I53 and a seat I54 therefor. A piston I55 is formed integral with the valve member I53. A bleeder hole I56 passes throughthe piston I55 and serves to allow fluid under pressure to pass therethrough into a valve chamber I51. The valve chamber I51 is connected by means of a passage I58 with the ball 5 check valve I59 which isflnorm'ally, held in a seated or closed'position by means of acompression spring I50. An adjusting screw IBI is provided for adjusting the compression of the spring I60 as desired.

In order to reduce the pressure in the fluid system to substantially zero, a venting control is provided for relieving the pressure within the valve chamber I51. The passage I58 is connected with'apassage I62. The passage I52 is drop the pressure of machine is idle,

in turn connected with a pipe I63 "which conmeets with the auxiliary control valve I Ill. .A pipe 164 connects the balanced-pressure relief valve I52 with the reservoir '46. When the auxiliary control valve stem I 08 is moved into the right-hand position (Fig. 9), the venting pipe with a valve valve .pistons IN and .1II2 and .pass through holes I 67 into a centralaperture I68 within the valvestem I08 and outwardly through holes I69 into the valve chamber I I5 located between the valve pistons I08 and III] and through the exhaust pipe I I6 into the reservoir 46. When the venting pipe I63 isopened to the exhaust, fluid under pressuremay pass through the bleeder hole I 56,, the valve chamber I51, the passage I58, the passage I62 and through thepipeI63 which. exhausts directly into the reservoir 46, thus unbalancing the pressures on opposite sides of the piston I55 so that the piston remains open and allows substantially unrestricted passage of fluid under pressure directly through the chamber I51 and the pipe I63finto the reservoir 46, thus reducing the fluid pressure in the entire hydraulic system substantially. to zero during the time the ma chine idle.

The operation of this improved grinding machine will be readily apparent from the. foregoing disclosure. A work piece (not shown) ,is themain control lever I2?! is positioned in position I a (Fig. 5). In order to locatethe table in the desired position ioragrinding operation,

. the lever I20 is shifted from position I20a into position 120b, after which it may be moved either toward the left into position I-Z-Oc to cause the table I'5 to move toward the left or tion I200? to cause the table I5 to move toward the right so as to facilitate positioning a, work piece a predeterminedposition relative to the grinding wheel. After the work, piece has been positioned in the desired location the control IZIlhafter which lever I20 is shifted into position it may be moved forward toward the operator into position I200 to admit fluid under pressure to the wheel slide cylinder 24 so as to initiate a forward feeding movement of I2. After the work piece has been ground to the desired and predetermined size,the control lever I20 may be a ain shifted from position ling into position mm, which movement serves to shift the valve40 so as to cause a rearward movement of the grinding wheel I2. When the lever I20 reaches the position I2fla, theauxiliary control valve is shifted to its rearmost position so that the venting pipe IE3! is openedto allow fluid under pressure to exhaust from the balanced pressure relief valve I52 through the pipe I53 and through the valve I01 into the exhaustpipe I I 6 and return the same to the reservoir 46. The venting fluid within the hydraulic system substantially to zero during the time the thus preventing wire drawing of the oil and excessive heatingthereof.

During the positioning movement of the table by movement of'the control lever, if it is desired to slow down the rapid traverse of the table from a. normal speed to a slow-down speed, the control lever may be shifted from position I2Il into position I20). This movement serves to shift the valve 55 so that fluid exhausting therefrom, instead of exhausting through the normal exhaust pipes 65 into posiof the valve I52 serves tov l20e or from position I20d into position actuates a limit switch located in position on the Work table I5 while 330 the'grinding wheel and 66, will exhaust through pipes -61 and 68 and pass through the throttle valves '69 and lflwhich are regulated to produce the desired slow movement of the work table I5.

When it is desired to change the normal traversingspeed of either the work table I5 or the wheel slide Ii, that is, for either a slow-down or a speed-up movement thereof, the operator Hll which is located on the hand control lever I2-il. Actuation of the switch I18 serves to energize the solenoid 89 and thereby to shift the stern I6 of the valve 15 toward the right. If the valve 15 is a normally open valve, as shown in Fig. 1, energization of the solenoid 89 serves to close the valve and; thus to slow down must pass through the throttle valve 13 to produce a slow traversing or feeding movement thereof. It. the valve 7 5 is arranged as a normally closed valve, as illustrated inFig. 7, movement of the valve stem 16 toward the right upon energization of the solenoid ;89 serves to open the valve to allow substantially unrestricted exhaust ofMflu-id from the pipe 90 to pass through pipe 92 into the reservoir 46, thus producing a speedup movement of either the worktable I5 or the wheel slide II, depending upon which is operative.

It will thus be seen that there has been provided by this invention apparatus .in which the various objects with many thoroughly practical advantages are successfully achieved. As many possible embodiments may be made of the above invention control valve for said valve for said wheel slide a manually operable control. lever table cylinder, a control cylinder,

I which is operatively connected to actuate both of the wheel slide. l 2. In'a grinding machine having a base, a longitudinally movable work table thereon, a piston and cylinder to traverse said table, a rotatable the exhaust of fluid from either I the table or the wheel slide cylinder so that hereinabove set forth together .operatively connected to actuate exhaust and thereby ment'ofeither the table or the wheel slide.

3. In a grinding machine having a base, a 1ongitudinally movable table thereon, a piston and cylinder to traverse said table, a rotatable grinding wheel, a transversely movable grinding wheel slide, a piston and-cylinder to feed said slide in either direction, a controlvalve for said table cylinden'a control valve for said wheel slide cylinder, a manually operable control lever which is operatively-connected to actuate both of said valves, a throttle valve to control the exhaust of fluid from both of said valves, means including a normally open solenoid actuated valve to by-pass exhaust fluid around said throttle valve normally to allow substantially unrestricted exhaust of fluid-to control the normal speed of the table or wheel slide, and means including an electric switch on said control lever which is operatively connected to actuate said solenoid to close said solenoid actuated valve to slow down the rate of movement of either the table or the wheel slide.

4. In a grinding machine having a base, a longitudinally movable table thereon, a piston and cylinder to traverse said table, a rotatable grinding wheel, a transversely movable grinding wheel slide, a piston and cylinder to feed saidslide in either direction, a control valve for said table cylinder, a control valve for said wheel slide cylinder, a manually operable control lever which is both of said valves, a throttle valve in said exhaust pipe to control the exhaust of fluid from both of said valves, a normally closed solenoid actuated valve to byass fluid around said throttle valve,-and means'including an electric switch on said control lever which is operatively connected to actuate said solenoid to open said valve so as to allow substantially unrestricted exhaust of fluid to speed up the rate of movement of either the table or the wheel slide.

5. In a grinding machine having a base, a longitudinally movable work table thereon, a piston and cylinder to traverse said table, a rotatable grinding wheel, a transversely movabl grinding change the rate of move.-

wheel slide, a piston and cylinder to feed said slide in either direction, a control valve for said table cylinder, a control valve for saidwheel slide cylinder, a manuallyoperable control lever which is operatively connected to actuate both of said valves, said connections when the lever is moved in one direction it serves to actuate the table control valve and when moved in a second direction serves to actuate the Wheel slide control valve, a throttle valve to control the exhaust oi fluid from both of said valves, means including a solenoid'actuated valve to bypass fluid around said throttle valve, and means including an electric switch on said control lever which is operatively connected to actuate said solenoid so as to change the rate of exhaust and thereby change the rate of movement of either the table or thewheel slide. 1

6. In a grinding machine having a base, a longitudinally movable work table, a piston and cylinder to traverse said table, a rotatable grinding wheel, a transversely movable grinding wheel slide, a piston and cylinder to feed said slide in either direction, a control valve for said table cylinder, a control valve for said wheel slide cyl-' inder, amanually operable control lever which is operatively connected to actuate both of said valves, a common exhaust pipe to return fluid exhausting from both of said control valves, a sole being arranged so that,

in said system normally tomaintain a noid valve in said exhaust pipe line normally to allow unrestricted exhaust of fluid .from said valves, meansincluding a throttle valve to bypass exhaust fluid around said: solenoid valve when said solenoid valve is closed to produce a slow movement of either the table or the wheel slide, and means including a limit switch on said control lever which isoperatively connected when closed to actuate and close said solenoid vvalve after which fluid exhausts through said throttle valve to facilitate slowing down either the movement of the table or the wheel slide.

'7. In a grinding machine having a base,'a longitudinally movable work table thereon, a piston and cylinder to move said table in either direction, a transversely movable grinding wheel slide, a. piston and cylinder-to feed said slide in either direction, a control valve to control the direction and speed of movement of said table, a second control valve to control the direction of movement of said wheel slide, a manually operable control lever which ls connected to actuate both of said valves, a return fluid exhausting from both of said cylinders through said control valves, a solenoid valve in said exhaust line which is normally open to allow unrestricted exhaust of fluid from either of said valves so that either the table or the wheel slide' will move at a relatively fast speed, means including'a throttle valve to by-pass fluid around aid solenoid valve when said solenoid valveis closed, and means including a limit switch on said control, lever which is'operatively connected to close said solenoid valve so as to facilitate slowing down the movement of either thetable or the wheel slide, v

8. In a grinding machine as claimed in claim 1, the combination with the parts and features therein specified, of an auxiliary valve which is operatively connected to control the direction of movement of the steadyrest shoes, operativeconnections between said auxiliary valve and said control lever whereby said auxiliary valve is actuated in timed relation with said wheel slide control valve. l r

9. In a grinding'machin'e as claimed in claim 1, the combination with the parts and features therein specified, of a balanced type relief valve predetermined operating pressure in said system, and an auxiliary valve whichis actuated by said control lever when moved to a predetermined position in one directionto vent automatically to reduce the pressure in said system when both the table and wheel slide are inoperative. w

v 10. In a grinding machinehaving a base, a longitudinally movable work table, a piston and cylinder to traverse said table a rotatable grinding wheel, a transversely movable'grindingwheel common exhaust pipe to and open said relief valve for said wheel slide cylin-- (HERBERT A. Sl ILVEN.

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