US1905127A - Hydraulically operated grinding machine - Google Patents

Description

April 25, 1933. A. G. BE LDEN El AL HYDRAULICALLY OPERATED GRINDING MACHINE 3 Sheet s-Sheet Filed April 8, 1929 ill/ Ill/l gvvuenfozs v .ALBEHT G. BELDEN HERBERT fl.SlLv:-

attorney April 25, 1933. A. G. BELDEN- ET AL 1,905,127

HYDRAULICALLY OPERATED GRINDING MACHINE Filed April 8, 1929 s Sheets-Sheet 2 1!" IIIJVIIIIIIIIIIIIIIIII la /11mm WITNEssEs ALBERT G. BELDEN HERBERT H.5ILVEN 6am H as w Patented Apr. 25, 1933 UNITED STATES PATENT OFFICE ALBERT G. BELDEN AND HERBERT A. SILVEN, OF WORCESTER, MASSACHUSETTS, AS-

SIGNORS TO NORTON COMPANY, OF WORCESTER, MASSACHUSETTS, A CORPORATION 7 OF MASSACHUSETTS HYDRAULICALLY OPERATED GRINDING MACHINE Application filed April 8, 1929. Serial No. 353,531.

This invention relates to grinding machines and more particularly to an interlocked hydraulic control forcontrolling the various mechanisms of the machine.

Heretofore numerous grinding machines have been developed in which hydraulic mechanisms are provided for operating the various moving parts, such as the work table, the wheel slide, and the work rotating mechanism. These mechanisms have all been individually controlled. However, for a precision grinding machine doing rapid production work requiring a multiplicity of grinding operations on each piece of work in certain types of grinding, such as the grinding of crankshafts and the like, it is necessary to employ a straight infeed of the wheel, and it is important that there be no endwise movement of the work table during this infeed. Likewise, when the grinding has been completed and the grinding wheel removed to an inoperative position, it is necessary that there be no feeding movement of the grinding wheel while the operator is traversing the work table to bring a second portionof the work into operative relation with the wheel. It is also desirable, for certain types of grinding, to utilize a fluid operated clamping mechanism for the work, such as shown in our copending application Serial No. 317,820 of November 7, 1928 (U. S. Patent No. 1,837,342 granted December 22, 1931), and in that case there should be no feeding movement of the grinding wheel or traversing of the work table until the work has been clamped in position. Similarly, it is necessary that the wheel slide and the work table be stationary during the unclamping of the work to prevent the work being brought against the grinding wheel with a consequent breaking of the wheel; and damaging the work piece or injuring the operator.

It is one object of'this invention to provide a control for a grinding machine which is so arranged as to permit the operation of any one of several grinding machine mechanisms but to prevent the others from being operated during the same time.

It is a further object of this invention to provide a hydraulically operated grinding machine which has a main fluid control valve to regulate the admission of fluid to the table traversing mechanism, the Wheel feeding mechanism and to other mechanisms, if such is desirable, but which is so arranged that only one of these mechanisms may be operated at a given time.

It is a further object of this invention to provide a main control valve to regulate the admission of fluid to any one of several mechanisms in a hydraulically operated grinding machine which prevents admission of fluid to more than one mechanism at a time, and to provide each of these mechanisms with an individual control so that the direction of movement of the machine parts may be changed as desired.

It is another object of this invention to provide a throttling device operable by means of a main control lever to permit the operator to shift from a rapid traversing speed for positioning the work to a very slow but uniform speed for truing the grinding wheel and which is so arranged that the operator may readily shift from a positioning speed to a truing speed.

Other objects will be apparent from the following disclosure. One embodiment of this invention has been illustrated in the drawings in which like reference numerals indicate like parts:

Fig. 1 is a diagrammatic perspective view showing the operating mechanism in one embodiment of this invention;

Fig. 2 is a fragmentary horizontal section on an enlarged scale through the control lever and the table traverse control valve;

Fig. 3 is a fragmentary horizontal sectional View on an enlarged scale through the main control valve, the wheel feed control valve and the table truing speed throttle valve;

Fig. 4 is a diagrammatic sectional view similar to Fig. 3 on a reduced scale showing the main control valve in position to admit fluid under pressure to a grinding machine operating mechanism, such as a work clamp ing mechanism, as shown in our U. S. Patent No. 1,837 ,342;

Fig. 5 is a sectional view similar to Fig.

' to admit fluid to the left-hand end of the feed cylinder to move the slide rearwardly;

Fig. 7 is a similar View to Fig. 6 with the main control valve in position to admit fluid t0 the feed mechanism but with the feed con trol valve arranged to admit fluid under pressure to the right-hand end of the feed cylinder to feed the grinding wheel into the work;

Fig. 8 is a longitudinal sectional view through the throttle valve in the traverse mechanism showing the V-port to control the exhaust of fluid from the traverse mechanism so that the table may be traversed at a rapid rate to position the work or at a very slow rate when it is desired to true the wheel; and

Fig. 9 is a fragmentary cross sectional view of the wheel feed mechanism.

This invention comprises a grinding machine, and preferably one that is hydraulically driven, in which a main control device is arranged to control a plurality of operating mechanisms of the machine and prevent all but one of the mechanisms from being operated at a given time. In a hydraulic machine a main control valve may be provided for this purpose, and. it may be arranged to admit fluid through a suitable reversing valve to a feeding mechanism which serves to feed the grinding wheel and its supporting slide either toward or from the work, or to admit fluid under pressure through a suitable control valve to a cylinder connected to traverse the work supporting table in either direction and position the work relative to the grinding wheel. The main control valve may also be connected to control a work supporting and rotating head (not shown) as illustrated in our U.'S. Patent No. 1,837,342. The feeding movement of the grinding wheel is caused by a fluid pressure operated piston and eylinder mechanism which is operatively connected to the end of the main feed screw to move the feed screw axially. The feeding screw is also connected with a suitable manually operable feeding mechanism so that the operator may adjust the osition of the grinding wheel relative ,to the piston in the fluid pressure mechanism. Also, a readily accessible mechanism is provided for changing the traverse speed of the table from a rapid speed for positioning the table relative to the grinding wheel to a very slow speed for truing or dressing the grinding wheel. This invention further provides for a single control lever connected to operate the main control valve which not only admits fluid under pressure-to the various mechanisms but also controls a throttle valve which regulates the speed of the table traversing mechanism.

As illustrated in the drawings, a grinding machine is provided having a base 11, a work supporting table 12 slidably mounted on the flatway 13 and V-way 14 011 the base of the machine. A wheel slide 15 having a rotatable grinding wheel 16 is'slidably mounted on the fiat way 17 and V-wa'y 18 for movement transversely of the machine base.

Wheel feeding mechanism The grinding wheel 16 may be fed toward and from the work by a suitable fluid pressure mechanism, such as a cylinder which is preferably fixed relative to the base 11 and provided with a piston 26 slidably mounted therein. The piston'is connected to one end of a piston rod 27, the other end of which is suitably connected to the Wheel slide 15 so as to move the slide towards or from the work depending upon the direction of flow of fluid in the cylinder 25. A reversing valve 30 is provided to control the direction of movement of said piston and wheel slide to feed the grinding wheel either towards or from the work. This valve is preferably of a balanced piston type and is provided with a pair of pistons 31 and 32 mounted on the valve stem 33 which are slidable within the valve chamber 36. The fluid under pressure is admitted to the valve through a conduit 35 which conveys the fluid to the valve chamber 36 between the pistons 31 and 32. As shown in Fig. 1 the balanced piston valve is shown in a neutral position so that the ports 37 and 38 are both closed.

To control the movement of the valve 30, a lever 10 is pivotally mounted on the base of the machine by a stud 41. The lower end of the lever 40 is connected by a pin 42 to a bifurcated projection 43 on the outer end of the valve stem 33. When it is desired to move the grinding wheel either toward or from the work, the operator swings the lever 40 in the direction in which he desires the wheel to move. If it is desired to feed the grinding wheel into the work, the operator pulls the lever 40 away from the machine into position 4011 as shown in dotted lines in Fig. 1 to move the valve pistons 31 and 32 into the position shown in Fig. 7 This movement opens the port 38 and adm1ts.flu1d under pressure through the pipe 45 into the cylinder chamber 46 at the right-hand end of the cylinder 25 as viewed in Fig. 1. This pressure in the chamber 46 forces the piston 26 towards the left as viewed in Fig. 1 to feed the grinding wheel and slide toward the work. The movement of the piston 26 toward the left, forces fluid from the cylinder chamber 47 through the port 48, the pipe 49, the port 37 into the valve chamber 50, and from this chamber through a port 51 and pipe 52 to the main exhaust pipe 53 which end of cylinder 60 to force the piston 61 toempties into the fluid reservoir or tank 54.

If it is desired to move the grinding wheel and slide rearwardly to an inoperative position so that the grinding wheel is out of contact with the work, the operator swings the lever 40 towards the machine into position 40?), as shown in dotted lines in Fig. 1, so that the valve pistons 31 and 32 are arranged as shown in Fig. 6. In this position of the feed control valve, fluid entering through the conduit 35 into the valve chamber 36 passes through the port 37, the pipe 49 through the port 48 into the chamber 47 at the left-hand end of cylinder 25, as shown in Fig. 1. The fluid under pressure entering chamber 47 moves the piston 26 and consequently the grinding wheel 16 and wheel slide 15 in a rearward direction toward the right, to an inoperative position out of contact with the work. It will thus be seen from this construction, that the operator by movement of the feed control lever may maintain the valve 30 in a neutral position or may shift the valve to cause either a forward. or rearward movement of the grinding wheel.

Table traverse mechanism The table 12 may be traversed in either direction by a suitable fluid pressure operated mechanism, such as a cylinder 60 supported in the base 11 of the machine. Th1s cylinder is diagrammatically shown in Fig. 1 but with the connections between the cylinder and the base removed. A piston 61 is slidably mounted within the cylinder 60 and is connected to one end of a piston rod 62. The other end of the rod 62 is connected to a bracket 63 depending from the under side of the table 12. A valve 65, preferably of the balanced plston type, is provided to control the direction of movement of the piston 61 and also the table 12. This valve comprises the pistons 66 and 67 mounted on a valve stem 68. Fluid is ad- 66a and 67a.

mitted to chamber 70 of the valve 65 through a pipe 69. A valve 65 is shown in a neutral or inoperative position in Fig. 1, that 15, so that pistons 66 and 67 close the ports 71 and 72. A control lever 73 is mounted on the outer ends of a rock shaft 74 WhlCh may be supported in suitable bearings (.not shown) in the base 11. The other end of the shaft 74 is provided with a lever 75 the upper end of which is connected by a pin 76 to the valve stem 68. I

If it is desired to traverse the table 12 toward the left, the operator grasps the control lever 73 and swings the lever towards the left into a posit-ion shown in dotted lines 7 3a in Fig. 1. This movement shifts the valve pistons 66 and 67 into new positions In this position, fluid under pressure entering through the pipe 69 into the valve chamber 70 passes outwardly through the port 71, pipe 79, and port 80 into the cylinder chamber 81 at the right-hand wards the left, as viewed in Fig. 1, and thereby traverse the table 12 towards the left. During this movement of the piston 61, fluid is exhausting from the cylinder chamber 82 through a port 83, pipe 84, port 72 into the valve chamber 85 in the valve 65. This fluid then exhausts through port 86 and pi 87.

When it is desired to move the tab e 12 in the opposite direction, that is, towards the right, the operator moves the lever 73 into the position 736 as shown in dotted lines which in turn moves the valve pistons 66 and 67 into the dotted positions indicated as 66?) and 67b in Fig. 2. In this position of the valve, fluid under pressure entering through the pipe 69 passes through the valve chamber 70, port 72, pipe 84, cylinder port 83, and into the cylinder chamber 82 to force the piston'61 towards the right, thereby moving the table 12 towards the right. During this movement of the piston 61, fluid is exhausted from the cylinder chamber 81 through the port 80, pipe 79, valve port 71, and into the valve chamber 90. The fluidv then passes through an exhaust port 91 and passage 92 and out through the exhaust pipe 87 It will be readily seen from this construction, that movement of the traverse control lever 73 may control the movement of the table so that it may be held stationary when the lever is in a central position or traversed towards the right or the left depending upon the di-' rection in which the operator shifts the lever from its central position.

Main control valve fed into the work. so as to eliminate the danger of the grinding wheel being jammed into a shoulder on the work piece. It is likewise desirable that the feeding mechanism be arranged so that the operator may not feed the wheel when the work is being traversed to position the work relative to the whee. In other words, it is desirable that an interlocked relationship be provided between the feeding and the traversing mechanisms so that only one of these may be operated at a given time. Hence, a main operating control valve 93 is provided to control the admission of fluid from the source of supply to the various operating mechanisms of the machine, and it is so arranged that fluid under pres sure may be admitted .to only one of the mechanisms at a time. As illustrated, this her 101.

A main control lever 102 is pivotally mounted on a yoked member 88 by a stud 103. The yoked member 88 is provided with.

an integrally projecting stud 89 which 18 journaled in the base 11 of the-machine. It will be readily appreciated from this construction that the lever 102 is movable in two directions, namely, longitudinally and transversely relative to the base. The lever 102 is operably connected to the valve stem 96 by means of a projection 104 on the end of the valve stem 96 engaging a T-slot 105. This connection permits movement of the lever towards and from the work to be trans mitted to give a corresponding movement to the main control valve. As shown in 1, the valve pistons 94 and 95 are positioned to admit fluid passing through port 106 and conduit into the valve chamber 36 in the grinding wheel feed control valve. This position of the main control valve is also illustrated in the diagrammatic showing in Figs. 6 and 7. In this position of the valve, fluid under pressure enters the feed control valve, and the operator by manipulation of the lever 40 may control the movement of the grinding wheel slide 15 to feed the grinding wheel either toward or from the work.

After the work has been ground to the required size and the grinding wheel has been removed to an inoperative position, the operator must then traverse the work table 12 to bring the next portion of the work piece into operating position relative to the grinding wheel. This is accomplished by moving the lever 102 away from the front of the machine into position 102a, as shown in dot ted lines in Fig. 2, -to shift the valve 93 so that the valve pistons are in the position shown in Fig. 5. In this position of the valve, the port 106 is closed and fluid entering through the port 100 into the chamber 101 passes through port 111, pipe 112, pipe 69 into the chamber 70 of the table traverse control valve 65. In this position of the main control valve, the operator by manipulation of the table traverse control lever 73 may traverse .the table 12 in either direction to position the work relative to the grinding wheel. It will be readily apparent from this illustration and description that either the wheel feed or the traverse mechanism may be operated singly, but the main control valve is so constructed and arranged that the two mechanisms may not be operated simultaneously.

It may be desirable for certain types of grinding to have another mechanism of the machine controlled by the main control lever and valve so that the three mechanisms may be separately controlled but only one of the three be operative at a given time. This third mechanism may be a work rotating and clamping mechanism as disclosed in our U. S. Patent No. 1,837,342. For this purpose, a port 107 and pipe 108 are provided in the main control valve 93 and arranged to be connected to the third mechanism. The valve pistons 94 and 95 may be positioned, as shown in Fig. 4, so that fluid under pressure entering the valve chamber 101 may pass through port 107 and pipe 108 to such mechanism. A suitable exhaust pipe 109 is provided to enable fluid from said mechanism exhausting into the valve chamber 110 to pass through pipe 109 into the main exhaust pipe 53 and into the reservoir 54. When the machine is idle, the valve stem 96 may be shifted to position the pistons 94 and 95, as shown in Fig. 3, so that fluid under pressure entering through pipe 99 and port 100into valve chamber 101 may exhaust directly through pipe 109 and pipe 53 back to the reservoir.

' Wheel truz'ng speed In a grinding machine of the cylindrical I type, such as shown in the drawings, the table traversing mechanism should be capable of being driven at a slow but uniform speedfor properly truing the grinding wheel. Also it is desirable to provide a suitable mechanism so that the operator may readily shift from the normal traverse speed for positioningthe work to a predetermined slow but uniform speed for truing the wheel. To accomplish this, there is provided a throttle valve 115 of the piston type which has a piston 116 slidably mounted therein and connected at one end to a piston rod 117. This piston 116 is arranged to cover or expose a V-shaped port 118. A V-shaped port, such as shown in Fig. 8, is utilized so that it is possible to get a large range of control and -when desired to permit only a very small this valve may be readily controlled to give the desired slow uniform truing speed, it is preferable to provide a simplified readily ac- CJSSlblB control, such as illustrated in the drawings. This comprises a bell crank lever 125 pivotally mounted on a stud 126 on the bracket 127 which is supported on the machine base. The arm 128 of the bell crank en gages the head 121' of the valve stem 117. The other arm 130 of the bell crank lever 125 is provided with an adjusting screw 131 which is arranged to be engaged by the control lever 102, when the control lever is swung from position 102a to position 102?), as shown in dotted lines in Fig. 2. When the lever is moved towards the right (Figs. 1 and 2), it engages the adjusting screw 131 and rocks the bell crank 125 about the stud 126 and moves the valve stem 117 and piston 116 towards the right as viewed in Fig. 1 to partially close the V-shaped port 118. By manipulation of the adjusting screw 131 the amount of swinging movement of the bell crank and the throttling movement of the piston may be varied to give the desired truing speed of the table 12.

By manipulation of the main control lever 102, the operator may admit fluid under pressure either to the feed mechanism or to the table traverse mechanism. This also operates to control the movement of the throttle valve 115. It will be apparent from this disclosure that the operator may readily change from the normal traversing speed to a predetermined uniform slow speed for truing the grinding wheel by shifting the main control lever from position 102a towards the right into position 102b, as shown in dotted lines in Fig. 2.

H and feed mechanism When setting up the machine or when compensating for grinding wheel wear, it is desirable to permit a manual adjustment of the grinding wheel relative to the fluid pressure feeding mechanism. A suitable nut and screw mechanism is provided, comprising a nut 135 depending from the wheel slide 15 which engages a feed screw 136. One end of the screw 136 is connected to the piston rod 27 by means of a bearing 137 interposed therebetween. The feed screw 136 is mounted for rotar as well as endwise movement so that the plston 26 may move the screw endwise tofeed the grinding wheel towards or from the work and the screw may be rotated to adjust the position of the grinding wheel relative to the .fluid pressure mechanism. The screw may be rotated by a manually operable feed wheel 138 mounted on the outer end of a shaft 139. A gear 140 is mounted on the-other end of the shaft 139 and in turn meshes with a second gear 141 which is keyed to a rotatable bushing 142 journaled in the base 11 of the machine. The outer reduced end portion 143 of the screw 136 is slidably keyed by akey 144 within the bushing 142.

admission of fluid to table traverse cylinder 60, The operator ma then by manipulation of the control lever 3 traverse the table in either direction to position the work piece 19 into proper relation with the grinding wheel 16. 'When the work has been brought into the desired position, the operator shifts the lever 73 to a central or neutral position, as shown inFig. 1, so that the table isheld against endwise movement. Next, the operator shifts the main control lever into po sition 102 (see Fig. 2). This movement, as

illustrated in Fig. 1, opens the port 106 in the main control valve 93 to admit fluid to the feed control valve 30. The operator may then by manipulation of the lever 40 as previously described feed the grinding wheel into the work to grind it to a predetermined size or move the wheel r'earwardly after the grinding operation has been completed. If it is desired to true the grindin wheel, the operator makes use of one of t e standard well-known types of truing tools which is preferably mounted on the work supporting table so that it may be traversed across the face of the wheel. The operator then shifts the main control lever 102 into position 102b,as shown in Fig. 2, which admits fluid to the table traverse control valve 65 and simultaneously shifts the throttle valve 115 to partially close the V-shaped port 118 to produce the desired slow but uniform movement of the table for truing the Wheel.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent is:

1. A grinding machine comprising a base,

ing wheel, a fluid pressure system including a pump to force fluid under pressure to said cylinders, a manually controlled valve mechanism to admit fluid to either of said cylinders while excluding it from the other, thereby preventing actuation of the slide and table simultaneously, and means for moving the slide independently of the fluid pressure actuated devices to adjust the position of the wheel relative to that of the work.

2. A grinding machine comprising a base, a work table slidably mounted thereon, a

grinding wheel slide, a rotatable grinding wheel on said slide, a fluid pressure opera'ted cylinder and piston arranged to reciprocate said table, a second cylinder and piston arranged to move said slide, a pump, a fluid pressure system connecting said pump and cylinders, means including a manually controlled valve arranged to admit fluid to either of said cylinders to move either the work table or grinding wheel slide, and a pair of manually controlled reversing valves interposed between the manually controlled valve and said cylinders to change the direction of flow of the fiiud to both of said cylinders and to reverse their directions of travel.

3. A grinding machine comprising a base, a work table slidably mounted thereon, a grinding wheel slide on said base, a rotatable grinding wheel on said slide, a cylinder and piston operatively connected to reciprocate said table, a cylinder and piston arranged to move said slide to feed the grinding wheel, a pump to supply fluid under pressure to said cylinder, a main control valve mechanism to admit fluid to either of said cylinders and simultaneously exclude it from the other, a second valve between the main control valve and said second cylinder to control the direction of flow of fluid to said cylinder, and manually operable means to shift said second valve to feed the grinding wheel either toward the work to size the same or to move it rearwardly to an inoperative position.

4:. A grinding machine comprising a base, a work table slidably mounted thereon, a grinding wheel slide on said base, a rotatable grinding wheel on said slide, a fluid pressure cylinder and piston operatively connected to reciprocate said table, a second cylinder and piston arranged to move said wheel slide toward and from the work, a pump in the base to supply fluid under pressure to said cylinders, a 'main control valve arranged to admit fluid under pressure to either of said cylinders, and simultaneously exclude it from the other, a second valve in terposed between the control valve and said first cylinder to control the direction of flow of fluid to said cylinder, and an adjustable throttle valve arranged to control the flow of fluid to or from said cylinder and vary the rate of movement of said work table to produce the desired grinding action.

5. A grinding machine comprising a base, a work table slidably mounted thereon, a grinding wheel slide on said base, a rotatable grinding wheel on said slide, a fluid pressure piston and cylinder operatively connected to reciprocate said table, a second cylinder and piston arranged to move said slide to feed the grinding wheel into the work, a pump in the base and piping to supply fluid under pressure to said cylinders, a manually operated main-control valve to admit fluid to either of said cylinders and simultaneously exclude it from the other, a second valve between the main control valve and the table traverse cylinder to control the direction of flow of fluid to said cylinder and thereby control the'direction of travel of said table, a throttle valve to control the table movement, and manually operable means to control said valves.

6. A grindingmachine comprising a base, a Work table slidably mounted thereon, a grinding wheel slide on said base, a rotat able grinding wheel on said slide, a cylinder and piston operatively connected to reciprocate said table, a cylinder and piston arranged to move said slide to feed the grinding wheel into the work, means including a pump to supply fluid under pressure to said cylinders, a main control valve to admit fluid under pressure to either of said cylinders, a manually operable lever to control said valve, a second valve to control the direction of movement of said fluid to said table traverse cylinder and a throttle valve arranged to throttle the flow of fluid through the table traverse valve and operable by movement of said lever to throttle the exhaust of fluid from said second valve to' give the table a very slow speed for truing the grinding wheel.

7. A grinding machine comprising a. base,

a work table slidably mounted thereon, a grinding wheel slide mounted on said base, a rotatable grinding wheel on said slide, a fluid pressure operated piston and cylinder operatively connected to move the slide in,

either direction, a second piston and cylinder operatively connected to reciprocate said table, a fluid circulating system to control admission of fluid under pressure to said cyinders including a main control valve arranged to admit fluid under pressure to either of said cylinders, a manually operable reversing valve interposed between said control valve and said second cylinder to control the direction of movement of the table,

a throttle valve normally biased to a closed position interposed between the reversing valve and the exhaust, and a single manually operable control lever movable to actuate said main control and throttle valves so as to successively produce a feeding movement of the grinding wheel, a rapid traverse of the table to position the same or a slow traverse of the table for truing the grinding wheel.

8. A grinding machine comprising a base, a work table slidably mounted thereon, a grinding wheel slide on said base, a.rotat able grinding wheel on said slide, a fluid pressure operated piston and cylinder, one of which is connected to reciprocate said table, a second fluid pressure operated piston and cylinder which are operatively connected to said slide to feed the grinding wheel towards or from the work piece to grind the same, a fluid pressure system to convey fluid under pressure to each of said cylinders, a manually operable control valve device arranged to admit fluid to either end of said cylinders and simultaneously exclude it from the other, and means independent of the control valve for controlling the direction of movement of both the table and the wheel slide, whereby either may be moved in either direction independently of the other.

9. .A cylindrical grinding machine comprising a base, a longitudinally movable work table thereon which is arranged to support a rotatable cylindrical work piece, a grinding wheel slide on said base, a rotatable grinding Wheel on said slide, a fluid pressure system including a piston and cyl- V inder operatively connected to traverse said table longitudinally relative to the base to position the work relative to the grinding Wheel, a second piston and cylinder operatively connected to move the slide transversely relative to the base 'to feed the grinding wheel into the work to size the same, a control valve device arranged to admit fluid to either of said cylinders and simultaneous: ly exclude it from the other, a manually operable control lever connected to actuate said valve so as to traverse the table and position the work piece relative to the grinding wheel while the wheel slide is held stationary or to teed the grinding wheel into the work to size the same while the table is held stationary, and means independent of the control valve for controlling the direction of movement of both the table and the wheel slide, whereby either may be moved in either direction independently of the other.

Signed at Worcester, Massachusetts, this sixth day of April 1929.

ALBERT G. BELDEN. HERBERT A. SILVEN.

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