US2171902A - Grinding wheel truing apparatus - Google Patents

Description

Sept. 5, 1939. w. H. WOOD GRINDING WHEEL TRUING APPARATUS Filed May 4, 1938 5 Sheets-Sheet 1 -WAL L.ACEH. W002 3 Sheets-Sheet 2 I87 I95 762 I76 H W. H. WOOD GRINDING WHEEL TRUING APPARATUS Filed May 4, 1938 Sept. 5, 1939.

Sept. 5, 1939. w. H. WOOD 2,171,902

GRINDING WHEEL mums APPARATUS Filed May 4, 1938 s Sheets-Sheet s jwtwwtoz WALLACE H. W001:

Patented Sept. 5, 1939 2,171,902 GRINDING WHEEL mums APPARATUS Wallace H. Wood, Worcester, Mass., asslgnor to Norton Company, Worcester, Mass., a corporation of Massachusetts Application May 4, 1938, Serial No. 206,027

8 Claims.

which the wheel and tool are relatively fed to-- ward each other at each end of the reciprocatory stroke. A further object of the invention is to provide an improved hydraulically operated wheel truing apparatus in which a hydraulically operated pawl and ratchet mechanism is arranged automatically to advance the truing tool at each end of its reciprocatory stroke. Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts, as 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 of this invention,

Fig. 1 is a front elevation of the improved truing apparatus mounted on a wheel slide having the wheel guard removed;

Fig. 2 is a right-hand end elevation of the improved truing apparatus, showing the wheel slide and the wheel driving motor;

Fig. 3 is a rear elevation of the improved truing apparatus;

Fig. 4 is a plan view of the truing apparatus;

Fig.. 5 is a hydraulic piping diagram showing the truing tool traversing and feeding mechanism;

Fig. 6 is a cross sectional view, on an enlarged scale, taken approximately on the line 6-6 of Fig. 1, showing the cam for causing a vertical movement of the truing tool and also the hydraulic truing tool traverse cylinder and associated parts;

Fig. 7 is a fragmentary vertical sectional view, taken approximately on the line 1-1 of Fig. 1;

Fig. 8 is a cross sectional view, on an enlarged scale, taken approximately on the line 8-8 of Fig. 1;

Fig. 9 is a fragmentary front elevation, on an enlarged scale, of the truing tool feeding mecha-' nism, having parts broken away more clearly to show the construction;

Another object of the invention is Fig. 10 is a fragmentary sectional view through the feed pawls;

Fig. 11 is a fragmentary plan view of the feed pawls as shown in Fig. 10;

Fig, 12 is a fragmentary sectional view, on an enlarged scale, taken approximately on the line l2-I2 of Fig. 9;

Fig. 13 is a cross sectional view, taken approximately on the line I3I3 of Fig. 12; and

Fig. 14 is a fragmentary sectional view, taken approximately on the line MI4 of Fig. 9.

The improved truing apparatus has been illustrated in the drawings as mounted fixedly on top of a wheel slide II) which rotatably supports a wheel spindle H carrying a plurality of grinding wheels l2 and I3 of the same or diiferent sizes or diameters. The grinding wheel spindle I I may be driven in any suitable manner, such as a motor drive in which an electric motor I4 is mounted on the upper surface of thewheel slide Ill. The motor is provided with a driving pulley l5 which is of the multiple V-groove type and transmits power by means of multiple V-belts Hi to a 'muIti-grooved pulley I! mounted on the outer end of the wheel spindle II.

The wheel slide Ill supports a frame or base H] of the truing apparatus. An adjustable horizontally arranged member I9 is pivotally connected by a stud with the frame l8. An adjusting screw 2| threaded into a lug 22 projecting from the base l8 serves to adjust the member I9 about its stud or pivot 20 to facilitate adjustment of the position of the member 19 relative to the base l8. A look nut serves to lock the screw 2| in adjusted position. The member I9 may be clamped in adjusted position on theframe I8 by means of clamping screws 25 which pass through elongated slots 26 in the lugs 21 on the frame l8 and are screw threaded into the member IS. A dovetailed slideway 30 is formed integral with the member l9 and is arranged to support a horizontally movable slide 3| having a dovetailed surface 32 which mates with the dovetailed slideway 30. Anadjustable tapered gib 33, interposed between the dovetailed ways 30 and 32, serves to take up lost motion between the fixed and movable parts of the slide. A screw 34 is provided to facilitate endwise adjustment of the gib 33.

The horizontal slide 3| is provided with a verticallyarranged member 28 which is formed integral therewith or fixedly mounted thereto. The vertically extending portion 35 on the horizontal slide 3| is provided with a dovetailed slideway 36 which supports a vertically movable slide 31 having a mating dovetailed way 38. An adjustable tapered gib 39 serves to take up lost motion between the dovetailed slideways 36 and 38, and a screw 40 serves to facilitate adjustment of the ib 39.

A second vertically arranged slide 41 is supported by a dovetailed slideway 42 formed integral with the vertically extending member 35. The dovetailed slideway 42 is provided with an adjustable tapered gib 43 having a screw adjustment 44. The slide 4| is preferably arranged so that it may be moved vertically during the horizontal movement of the slide 3|.

The vertical slide 31 adjustably supports a truing tool holder which in the present case is formed as a cylindrical bar 45 which is slidably keyed within an aperture 46 formed in a projection 41 of the slide 31. The truing tool holder or bar 45 is arranged to be clamped in adjusted position within the aperture 46 in the projection 41 of the slide. 31 by binding screws 48 and 49. The truing tool support 45 carries at its outer end a truing tool 50 having a diamond point 5| arranged for successively truing the peripheral surfaces of the grinding wheels l2 and I3.

The slide 4| is preferably adjustably connected to the slide 31 so that during the traversing movement of the horizontal slide 3|, the vertical slides 31 and 4| are moved together .in a vertical direction to control the path of movement of the diamond or truing tool 5|. The slide 4| is provided with a forwardly projecting boss or lug 52.

'A vertically extending feed screw 53 is rotatably connected to the lug 52 and extends downwardly -through a nut (not shown) which is carried by or formed integral with the slide 31. The lower end pf the screw 53 is journalled in and slidably keyed within a. spiral gear 55 which meshes with a spiral gear 56 formed on the inner end of a rotatable shaft 51. The shaft 51 is journalled in bearings 58 within the casing and is provided at its outer end with a manually operable hand wheel 59. By adjustment of the wheel 59, the feed screw 53 may be rotated to adjust the position of the slide 31 relative to the vertically movable slide 4|.

A poweroperated traversing mechanism is provided for producing a longitudinal traversing or reciprocating movement of the horizontally movable slide 3| to traverse the truing tool 5| relative to the periphery of the grinding wheels l2 and 13. In the preferred form a fluid pressure traversing or reciprocating mechanism is provided comprising a cylinder 60 which is formed within the member |9. A piston 6| is slidably mounted within the cylinder 68 and is connected to one end of a piston rod 62, the other end of which is fastened by nuts 63 to an end cap 64 formed integral with or fixedly mounted on the end of the horizontally movable slide 3|.

A fluid pressure system is provided to convey fluid under pressure to the cylinder 60. This system may comprise a reservoir 63 which is preferably located, within the base of the machine. Fluid is pumped from the reservoir 63 through a pipe 64 by means of a pump 65 which is preferably a motor driven fluidpressure pump of a standard well known type. Fluid under pressure from the pump 65 passes through a pipe 66, a portion of which is flexible hose; to a control valve 61. A pressure relief valve 68 is: connected with the pressure pipe 66 by 'a short pipe 69 and serves to. relieve excess pressure in the system and return it to the reservoir 63 through a pipe 16.

The control valve 61 is preferably a piston type valve and is arranged to control the admission and exhaust of fluid to and from the truing tool traverse cylinder 66 and also to "control the admission of fluid to a truing tool feed mechanism to be hereinafter described.

. e control valve 61 is provided with a valve stem 15 having formed integrally therewith a plurality of valve pistons 16, 11, 18 and 19. Fluid under pressure passing through the pipe 66 enters a chamber 8|] between the valve pistons 16 and 11 and passes out through a pipe or passage 8| into a cylinder chamber 82 at the left-hand end of the' cylinder 68 (Fig. 5) to move the piston 6| toward the right, which serves also to move the horizontalslide 3| and the truing tool 5| toward the right to its extreme right-hand position, asindicated in Figs. 1 and 5. During the movement of the piston 6| toward the right, fluid within a cylinder chamber 83 exhausts through a pipe or passage 84 into a valve chamber 85 located between the valve pistons 11' and 18 and out through a pipe or passage .86 into the reservoir 63. Similarly, when the valve stem -15 is shifted toward the right (Fig. 5), fluid under pressure from the pipe 66 passes through pipe 66a into the valve chamber 85 between the valve pistons 11 and 18 and passes through the pipe or passage 84 into the cylinder chamber 83 to cause the piston 6| to move to-,

ward the left and also moving the slide 3| and the truing tool 50 toward the left. During this movement, fluid within the cylinder chamber 82 .passes out through the pipe 8| into the cylinder chamber 80 between the valve pistons 16 and 11 and out through the pipe or passage 86 to the exhaust.

A speed control mechanism is provided to control the speed of movement of the truing tool both during its idle stroke and during the traverse of the diamond 5| across the peripheries of the grinding wheels l2 and I3. It is desirable to provide a control valve mechanism in the exhaust pipe line or passage 86 so that the truing tool will traverse at a rapid rate during the idle stroke of the diamond 5| and will be automatically slowed down to a proper truing speed when the diamond 5| moves into operative truing engagement with the peripheries of the wheels l2 and I3. A speed control valve 96 of the piston type is connected atone end of the pipeline 86. The valve 90 is a piston type valve having a pair of valve pistons 9| and 92. Fluid exhausting through the pipe 86 enters a valve chamber 93 between the valve pistons 9| and 92 and in the position shown in Fig. 5 passes out through a port 94 and a pipe 95, a portion of which is flexible hose, .to the reservoir 63. In the position of thevalve 98 (Fig. 5), unrestricted exhaust of fluid from the pipe 86 passes out through the pipe 95 so that the piston 61 and slide 3| together with the diamond 5| will traverse at a maximum speed.

The valve pistons 9| and 92 are normally urged in a downward direction by means of a spring 96.

The lower end of the valve piston 92 is provided with a conical end portion 91 which rides upon an adjustable cam 98. The cam 98 is held in a relatively fixed position and is supported on the horizontally movable slide 3|. The control valve 61 and the speed control valve 98 are supported by the fixed member l9. When the slide 3| traverses toward the left (Figs. 1 and 5). the slide will travel at a rapid rate until the conical end 91 rides into a low portion 980. on the cam 98. The forward movement of the valve pistons 9| and 92 (Fig. 5) serves to close the port 94, after which fluid within the pipe 86 exhausts througha needle valve 99 and into the pipe 95 into the reservoir;63. By manipulating the needle valve 99, the speed of movement of the truing tool 5| during its truingtraverse across the face of the grinding wheels I2 and I3 may be regulated as desired. It will be readily apparent from the 9| and 92 are in a rearward position (Fig. 5)

foregoing disclosure that when the valve pistons the port 94 is wide open, allowing unrestricted exhaust of -fluid to allow the truing tool slide 3| to traverse at a maximum speed, and upon closing of the port 90 fluid vmust thereafter exhaust through the needle valve 99 to allow the traverse to continue at a slow truing speed. In truing a pair of spaced wheels I2 and I3, such as shown in Fig. 1, the cam '98 is arranged so that the grinding tool 50 will travel at a rapid rate until the diamond 5| is about to engage the periphery of the wheel I2, after which the truing tool 50 travels at a slow truing speed. When .the truing tool 50 leaves the wheel I2, due to a raised portion 981) on the cam 98, the traverse will resume a rapid idle traverse until the diamond 5| is about to engage the periphery of the wheel I3, at which time the control valve 90 again moves forwardly as the cone shapedfollower 91 rides onto the portion 980 of the cam 99 to slow down the traverse of the truing tool 50 to a truing speed to true the periphery of the wheel "I3, after which the follower 91 rides again upon a high portion of the cam to finish the stroke of the slide 3| at a rapid rate. This mechanism operates in a similar manner on the reverse stroke. By varying. the shape of the cam 98, the speed of the truing tool 50 may be readily controlled for truing either a pair of wheels, as shown in the drawings, or any other arrangement, such as a single wide faced wheel or a multiplicity of wheels arranged in spaced relationship on the end of the spindle II. The cam 98 is provided with elongated slots I and |0I through which clamping T-bolts I02 and I03 pass adjustably to secure the cam 98 onto an upwardly extending projection I04 of the horizontal slide 3|.

In truing a grinding wheel or a plurality of grinding wheels arranged in spaced relationship with each other, it is desirable toreciprocate the truing tool across the peripheral surface of the wheel either one or more reciprocations for each truing operation. In the disclosure in the drawings, a mechanism has been illustrated for controlling the valve 61 so that the truing tool 50 mayreciprocate continuously as many times as the operator desires.

A reversing mechanism is provided for automatically actuating the reversing or control valve 5! to control the continuous reciprocation of the truing tool 50. A pair of adjustable dogs I05 and I08 are adjustably supported by a T-slot I01 formed in .a projection of theslide 3|. A reversing lever I08 is supported on a vertically arranged rock shaft I09 which is journalled in bearings H0 and III which are supported on the fixed member I9. The rod I09 is rotatably supported. in the bearings H0 and III. A lost motion connection is provided between the rod I09 and the valve stem 15. A lever I I2 is rotatably supported by the upper end of the rod I09 and carries a pin H3 at its upper end which rides in a groove in the spool shaped member Ill which is formed integral with or fixedly mounted on the outer end of the stem 75. The lever II2 is free to rotate relative to the shaft I09. A member I I5 is keyed to rotate with the shaft I09 and is provided with two oppositely extending arms IIS and II! each of which is provided with an adjustable stop screw H8 and H9, respectively. The lever H2 is provided with two projecting arms I20 and |2I which are arranged in the path of the stop screws v H8 and H9. When the shaft I09 is rocked to reverse the valve Bl, the member 'I I5 rocks until the lost motion is taken up before the lever II 2 starts to move toshift the reversing valve 61.

. By manipulation of the screws 8 and H9, the

extent of lost motion between the member 5 and the lever 2 may be varied as desired.

support for a spring-pressed arrow pointed.

plunger I 20 which cooperates with the roller I25 and serves as a load and fire mechanism to control the reversalof the valve 61.

The reversing lever I00 is preferably pivotally supported by a stud I30. The stud I30 is supported by a member |3| which is rigidly clamped onto the vertical shaft I 09.' The reversing lever I00 is provided with a forwardly projecting, manually operable lever I32 by means of which the mechanism may be manually raising the control leve'r I320 (Fig. 6), the reversing lever- I08 may be dropped out of the path of the reversing dogs I05 and I05 to allow the slide 3| to move to its extreme right-hand position, as illustrated in Fig. 1, with the piston 5| bearing against the end of the cylinder 50.

When it is desired to start the truing operation, the operator manually rocks the lever I32 in a clockwise direction (Fig. 4) which serves to shift the valve stem '15 of the control valve 67 toward the right (Fig. 5) to start the movement of the piston'GI toward the left to cause a corresponding -movement of .thetruing tool 50. Due to the angled-off surface on the under side of the dog I05, the lever I32 will swing into position |32a and then drop into an operating position so that the reverse lever I08 lies in the path of the reversing dogs I05 and I 06. The reciprocation of the truing tool 50 andits supporting slide 3| continues until the wheels I2 and I3 have been trued to the desired extent, at which time the operator raises the controllevor I32 into position |32a to allow the slide 3| to traverse to an inoperative position toward the right, as shown in Fig. 1.

In order that the truingtool 50 may true'a plurality of spaced grinding wheels of diiierent diameters, such as a pair of spaced grinding wheels I2 and I3, respectively, it is desirable to provide a control mechanism to move the slides 31 and 4| in timed relation with the traversing or reciprocating movement of the horizontal slide 3| so that a single truing tool 50 may be utilized to true both wheels, that is so that the diamond 5| may pass across the periphery of the wheel I Zand then the slides 31 and AI may be moved into a second predetermined position to true the periphery of the grinding wheel I 3. Due to the short space between the two grinding wheelsand due to the difference in their diameters, it is not feasible to utilize a fixed cam bar for this purpose. To overcome this difliculty a rotatable cam I50 is provided to transmit a vertical motion to the slides 31 and 4|, which movement is controlled by the longitudinal traversing movement of the truing tool 50 and the horizontal slide 3|. The rotatable cam I50 is supported on a shaft I5I which is supported on the vertical member 35 which is integral with the horizontal slide 3|. The outer end of the shaft I5I is clamped and supported in a bearing I52 formed integral with a bracket I53 which straddles the slide 4| and is fixedly mounted on the vertical member 35. A follower controlled. By I32 tothe dotted position m is fixedly mounted on the vertically movable slide H and is arranged to engage the periphery of the rotatable cam I56.

In order to transmit the desired vertical movement to the truing tool '56 and its supporting slide 61 in timed relation with the traversing movement of the horizontal slide 6|, a rack'bar I55 is I a shaft supporting the cam is moved longitudinally during the traversing movement of the-slide 3| and the truing tool 56. The cam I56 is preferablydesigned to .give the desired vertical movement to the truing tool 56 and, as illustrated, comprises two concentric portions for holding the truing tool 56 against vertical movement during the interval in which it traverses across the periphery of the wheel, and the connecting portions between the two concentric surfaces are shaped to give a predetermined lift or drop to the truing tool 56 and its supporting slides 31 and H so that the diamond 5| may be readily moved after truing the larger diameter wheel I! down to a position to true the smaller diameter wheel I3 and vice versa when the slide 3| is traversed in the reverse direction.

In order to attain one object of the invention, an automatic feeding mechanism is provided for feeding the diamond SI and truing tool 56 and its supporting slide 31 downwardly at each end of the reciprocatory stroke of the slide 6 I so that the truing tool 56 will cutafresh path across the wheel periphery. In the preferred construction, an hydraulically actuated pawl and ratchet mechanism is provided incrementally to rotate the feed screw 53 at each end of the longitudinal traversing strokeof the slide -3I to re-position the truing tool 56 for the next traversing movement. A sleeve I66 is rotatably supported on a reduced portion I6I of the shaft 51. The sleeve I66 has formed integrally therewith an outwardly extending arm I62 having a gear segment I66 formed'at its outer end. The gear segment I63 meshes with a sl'idably mounted rack I64 formed adjacent to one end of a piston rod I65 having an integral piston- I66 fixed at'its right-hand end (Fig. 5). The piston I66 is slidably mounted within a fluid pressure cylinder I61. A spring I66 surrounding the piston rod I65 and interposed between the piston I66 and a shoulder I69 within a casing .I16'serves normally to urge the piston I66 in a direction toward the right (Fig. 5). when fluid under pressure is admitted through a pipe "I into a cylinder chamber I11 the piston I66 is moved toward the left (Figf5) against the compression of the spring I66 to move the rack bar I64 toward the left and to swing the gear segment I63 and associated parts in a counterclockwise direction (Fig. 5).

The sleeve I66 is also provided with a radially extending arm I15 which supports a stud I16 at .its outer end; The stud I16supports a pair of pawls I11 and I16 which are arrangedto engage a ratchet wheel I19 which is in turn rigidly fixed to rotate with the hand wheel 56. The hand wheel 56 is keyed to a'reduced end portion of the shaft. The pawls I11 and I16 vary in length by an amount substantially equal to one-half of a ratchet tooth; The pawls I11 and I18 are normal- 1y held in an operating position by, means of a spring-pressed plunger I66 which notchesin the stud I16 and may be moved into an Y engages inoperative position by means of a manually operable lever I6I.

The lever I6I is fastened to the pawl I 11. The pawl I11 is provided with a clearance hole I62. A pin I66 i s fixed to the pawl I16 and passes through the clearance hole I62 so that when the pawl I11 is swung to and from an operating position by means of the lever I6 I, the pawl I16"wi1l also be moved by means of the pin I66.

It will be readily apparent from the foregoing disclosure that when the pawl carrying stud I16 and pawls I11 and I16 are oscillated in either direction by the spring I66 or by the admission of fluid under pressure into the cylinder chamber I12. the pawls I11 and I16 will be caused to oscillate, either riding idly over the ratchet wheel I16 when moved in a clockwise direction (Figs. 1 and 9) or will rotate the ratchet wheel I16 when moved in a counterclockwise direction.

In order that the extent of feed of the diamond 5I or truing tool 56 may be regulated and con-' counterclockwise direction (Figs. 1 and9) to turn the feed screw 53 and thereby advance the diamond 5| toward the wheel axis so that upon its next traversing stroke across the wheels, it will true a predetermined amount oil the wheels. The engagement of the end of the piston rod I65 with a stop screw I64 serves to limit the movement of the pawls I11 and I16 in a counterclockwise direction.

The spring I66 serves to return the piston rod I65 toward the right (Fig. 5) to return the feeding mechanism parts, namely the pawls I11 and I16, to their initial position ready for the next feeding movement. In order to adjust the extent of infeeding movement, a stop device is provided for limiting the movement of the pawls I11 and I16 intheir idle movements in a clockwise direction (Figs-1 and 9). An arcuate slideway I65 is fix-' edly secured to the casing, I16'and serves as a support for an arcuate slide I66 which is previded with astop abutment I61. By adjusting the position of the'arcuate slide I66, the position regulate the extent "of movement of the pawls-I11 and I16 in their idle stroke over the teeth of'the slideway' I65 is formed as a worm segment I66.

A worm. I66 is rotatably supported in a housing 'I66 which is pivotally supported by a stud I91 carried by the slide I86. The worm I89 is ar-' 1 of the abutment I61 may be varied asdesired to ranged to mesh with the worm segments I66. In case it is desired to make aquick adjustment of the abutment l61, the-casing I66 may beswung in a. counterclockwise direction about the 'stud I6f as a pivot to throw the worm I66 out of mesh I with the worm segment I68 and the slide I66 may then be adjusted on its arcuate slideway 165' and the worm I66 again thrown into mesh with theworm segment I66. The worm I66 is rotat ably supported in the casing I66 in bearings and.

is supported so that it may be rotated manually precisely to adjust the.position of the abutment I61 by means of aknob I62 which is mounted ,on-the outer end of the shaft for the worm I86.

' ried by the knob I92 and a fixed index point I94 is provided on the casing I90 so that the abutment I81 may be precisely adjusted to reposition the arm I15 as desired. It will be readily apparent from the foregoing disclosure that when the pawls I11 and I 18 are moved idly over the ratchet wheel I19 in a clockwise direction (Figs. 1 and 9) by means of the released compression of the spring I68, the movement will continue until an abutment I95 carried by the arm I15 engages the adjustably fixed abutment I81 which stops the movement of the piston I66 toward the right (Fig. 5) under the influence of the spring I68. The pawls I11 and I18 are then in position for the next infeeding movement. To facilitate holding the knob I92 in its adjusted position, a spring-pressed plunger 200 is carried by the frame I90 and is arranged to engage one of a plurality of holes or depressions 20I within the portion I93 of the knob I92.

The fluid pressure system is. preferably arranged so that fluid under pressure may be admitted through the pipe I'II into the cylinder chamber I12 to actuate the feeding mechanism to advance the truing tool 50 at each end of its reciprocatory stroke. This is preferably accomplished by providing a valve mechanism which is controlled in timed relationship with the traverse control valve. In the preferred construction, as illustrated in the drawings, the righthand end of the valve 61 is arranged so as to control the admission of fluid to the feed cylinder I61 at each end of the tool stroke so as to advance the diamond 5| toward the wheel axis before the tool starts its traversing movement in the reverse direction. The right-hand end of the valve stem 15 is provided with a central aperture 205. When the valve stem 15 is moved toward the right to reverse the-direction of fluid under pressure to the traverse cylinder 60, the ports 206 within the piston 18 pass a port 201 in the valve sleeve and fluid under pressure from the pipe or passage 66a passes through the port 201, the port 206, into the central aperture 205 within the valve stem 15, and out through apertures 208 and a port 209, into the pipe "I, into the feed cylinder chamber I12 to move the piston I66 toward the left (Fig. 5) against the compression of the spring I68 to move the feed mechanism part in a counterclockwise direction (Figs. 1, 5 and 9).

The valve stem 15 in reversing moves so that the port 206 in the valve piston passes by the port 201. After the port 206 passes the ports 201 in the valve sleeves, the piston 18 cuts off fluid under pressure from the feed mechanism and when the valve reaches its extreme right-hand position, fluid under pressure from pipe or passage 66a enters the valve chamber to admit fluid under pressure to the pipe or passage 84 to start the tool traverse toward the left. In the position of the valve as illustrated in Fig. 5, the released compression of the spring I68 exhausts fluid from the cylinder chamber I12, through the pipe I1I, which passes through the port 209 and ports 208 in the valve stem 15 into the central aperture 205 and exhausts out through ports 2I0 in the valve stem, into a pipe or passage 2 which conveys it to the reservoir 63.

It will be readily apparent that each time the valve stem 15 is moved either toward the right or toward the left, the ports 206 within the valve piston 18 will coincide with the port 201 in the valve sle'eve so that fluid under pressure from the pipe or passage 66a will be admitted to the feed cylinder chamber I12 to actuate the feed pawls I11 and I18 which in turnserve to turn the ratchet wheel I19 and the feed Wheel 59 to advance the truing tool 50 a predetermined distance toward the wheel axis at each end of the reciprocatory stroke of the truing tool 50'.

The operation of this improved truing apparatus will be readily apparent from the foregoing disclosure. Assuming all of the parts have been previously adjusted, that is, the dogs I05 and I 06 for length of stroke and the stop I81 for the amount of feed, the operation of the mechanism is initiated by the operator swinging the control lever I32 in a clockwise direction (Fig. 5) to shift the control valve 61 into its reverse position. During this movement, fluid passes through to the feed cylinder 60 to advance the truing tool 50 a predetermined amount before fluid is admitted through the pipe 84 to start the traverse of the slide 3I and diamond 5I toward the leftlFigs. 1 and 5). The diamond 5I traverses first at a rapid rate with fluid exhausting through the valve which is controlled by the cam 98. As the truing tool 50 approaches the side of the wheel I2, the released compression of the spring 96 cooperating with the cam 98 serves to close the valve 90 and thereafter fluid exhausts through the adjustable needle valve 99 into the reservoir 63 to traverse the truing tool 50 at a truing speed. During this movement the gear I56 rolling on the stationary rack I55 rotates the cam I50 so that when the truing tool 50 engages the periphery of the wheel I2, the follower I54 will be in engagement with a concentric portion on the cam I 50 so that there is no vertical movement of the truing tool 50'as it passes across the periphery of the wheel I2.

When the tool 50 has traversed across the face of the wheel I2, the continued longitudinal movement of the slide 3I rotates the cam I50 through a further extent to drop the truing tool 50 to position it for truing the wheel I3 to a second predetermined diameter and the follower I54 engages a second concentric portion on the cam I50 during the time the truing tool 50 is traversing across the periphery thereof. During this pass of the truing tool across the periphery of the two spaced grinding wheels I2 and I3, the speed of movement of the slide 3I is governed by the contour of the cam 98 which is arranged so that when the truing tool is out of engagement with the wheel peripheries, the slide 3I will travel at a rapid rate and when the tool is in truing engagement with either of the grinding wheels, the truing tool will be traversed at a predetermined slow truing speed.

The movement of the-slide 3| toward the left continues until the dog. I06 engages the reversing lever I08 which rocks the shaft I09, first taking up lost motion between the shaft I09 and the lever H2 and then causing the arrow pointed spring pressed plunger I28 to ride over the roller I25. After the high point of the arrow I28 rides by the periphery of the roller I29, the released compression of the spring quickly snaps the reverse valve 15 into its reverse position. During the shift-over of the reverse valve, fluid under pressure from the pipe or passage 66a passes through the valve port 201 above described into the pipe or passage "I to actuate the tool feeding mechanism to advance the truing tool 50 ready for the next traversing movement. The

diamond 5| will continue to traverse automati- 73 cally until the lever I32 is raised to the dotted position i320; when the slide 3| is moving in a direction toward the right which serves to throw the reversing lever I08 out of the path of the dog I05 to allow the truing tool to move to its extreme right-hand or inoperative position (Fig. 1). In this position of the parts, the piston El abuts against the cylinder head and the truing tool 50 and associated parts remain in this position so that the truing tool is out of engagement with the grinding wheels I2 and I3 during the grinding operation. I I

It will thus be seen that there has been provided' by this invention a wheel spindle positioning mechanism in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As various possible embodiments maybe made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.-

I claim:

1. In a grinding wheel truing apparatus, a truing tool, means to reciprocate said tool longitudinally, means including a rotatable cam and a follower to control the transverse movement of said tool, means actuated by the longitudinal movement of said tool to rotate said cam, and'an automaticallyactuated pawl and ratchet mecha-- anda' follower to control the transverse movemechanism automatically to feed said tool transversely at each end of its longitudinal stroke.

4. In a grinding wheel truing apparatus a truing tool,-means including a fluid operated piston and cylinder longitudinally to reciprocate said tool, means including a rotatable cam which is rotated in timed relation with said longitudinal reciprocation to move said tool transversely so as to control the position of the truing tool during a truing operation, means including a nut and screw mechanism to feed said tool transversely, a pawl and ratchet mechanism to actuate said nut and screw mechanism, and means including a fluid pressure operated piston and cylinder operatively connected to actuate said pawl and ratchet at each end of the longitudinal reciprocatory stroke of said tool.

5. In a grinding wheel truing apparatus, a truing tool, means including a fluid pressure operated piston and cylinder to reciprocate said tool longitudinally, a control valve .therefor, means including a rotatable cam and a follower, means including a rack and gear mechanism to rotate said cam in timed relation with said longie control the position of the tool dlu'inga truing operation, said cam being provided with one or more concentric portions to true cylindrical portions onone or more spaced grinding wheels,

means including a rack and gear mechanism which is actuated in timed relation with the longitudinal reciprocation ofs'aid tool to rotate said cam, means including a nut and screw feeding mechanism to feed said tool transversely, a pawl and ratchet mechanism to actuate said nut and screw mechanism, and means including a fluid pressure operated piston and cylinder oper- Y atively connected to actuate said pawl and ratchet at each end of its reciprocatory stroke.

7; In a grinding wheel truing apparatus, a,

truing tool, a vertically movable slide to support said tool, a horizontally reciprocable slide. to support said vertical slide. means including a rotatable cam and a follower transversely to control the position of the tool during the longitudinal movement of the horizontal slide and truing tool,

a fluid pressure piston and cylinder to reciprocate said horizontal slide, a control valve .therefor, a reversing mechanism including adjustable dogs on said horizontal slide, a reversinglever for actuating 'said control valve, means including a fluid pressure piston and cylinder operatively connected to adjust said vertical slide relative to said horizontal slide so as to produce a feeding movement of the truing .tool, said control valve being so constructed and arranged as to admit fluid under pressure to said second cylinder when the valve is shifted in either direction into a reverse position so as to actuate the infeeding of the truing tool at each end of the tool reciprocation.

8. In a grinding wheel truing apparatus, a

truing tool, a'vertically movable slide therefor,

a horizontally reciprocable slide to support said vertical slide, a fluid pressure piston and cylinder to reciprocate said horizontal-slide, means includinga rotatable cam and a follower'transversely to control the position of the truing tool during the longitudinal movement of said horizontal slide and truing tool, said cam being provided. with one or more concentric portions to position the vertical slide and truing tool to true cylindrical portions on one or more spaced grinding wheels of different diameters, a nut and screw to feed said vertical slide relative to said horiand ratchet, and a single control valve auto-' ma'tically to control the admission to and exhaust of fluid to reciprocate said horizontal slideandtraversethe truing tool and which during reversal of the valve serves to admit fluid under pressure to said second cylinder automatically strokef WALLACE H. WOOD.

-- to feed said truing tool at each end of the'tool

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