US3495360A - Apparatus for refinishing crankshafts - Google Patents

Description

Feb. 17, 1970 M. T. GEORGIAN 3,495,360 I APPARATUS FOR REFINISHING CRANKSHAFT'S v I 4 sheetss eet 1 INVENTOR. MICHAEL. T. GEORGIAN BY #246 Kw Filed Jan. 4, 1967 FIGZ Feb. 17, 1970 v M. T. GEORGIAN APPARATUS FOR REFINISHING CRANKSHAFTS 4 S eets-sheet 3 Filed Jan. 4, 1967 FIG. /5

FIG. 9

INVENTOR. MICHAEL'T. GEORGIAN Feb. 17, 1970 M. T. GEORGIAN 3,495,350

' APPARATUS FOR REYFYINISHING CRANKSHAFTS Filed Jan. 4, 1967 I 4 Sheets-Sheet 4 6 2% MM; W

United States Patent 3,495,360 APPARATUS FOR REFINISHING CRANKSHAFTS Michael T. Georgian, 7295 Rosernont, Detroit, Mich. 48228 Filed Jan. 4, 1967, Ser. No. 607,328 Int. Cl. 1324]] 19/12, 9/02 US. Cl. 51241 7 Claims ABSTRACT OF THE DISCLOSURE Apparatus for resurfacing the bearing surface of a crank pin without removing the crankshaft from the crankcase. A ring member positioned around the crank pin carries a plurality of grinding stones in contact with the bearing surface. Rotation of the ring produces a progressive radially inward movement of the stones so that the stones are at all times in grinding contact with the crank pin. The grinding faces of the stones are trued by a dressing apparatus clamped to the housing supporting the rotatable ring member.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to grinding and honing apparatus and more specifically to an apparatus for refinishing crank pin bearing surfaces Without removing the crankshaft from the engine or rotating the crankshaft.

Description of the prior art This application discloses improvements over the crank pin grinding apparatus disclosed in my Patent No. 2,566,660, issued Sept. 4, 1951. The crank pin grinding apparatus disclosed in my aforementioned patent takes the form of a ring supported in a fixed housing and positioned around the bearing surface of a crank pin. A plurality of annularly spaced grinding stones are coupled to the ring so that rotation of the ring produces progressively inwardly directed movement of the grinding stones so that they maintain a continuous abrasive contact with the surface of the crank pin. The ring is coupled for rotation to the output of a motor carried by the housing.

A problem associated with the arrangement of the aforementioned grinding apparatus is that rotation of the grinding stones produces reaction forces on the housing. Means were not provided for stabilizing the housing so that the grinding stones produce an uneven pressure on the crank pin bearing surface resulting in an uneven finish.

Another problem of my aforementioned crank pin grinding apparatus is that by supporting the motor to the ring housing, the overall size of the.apparatus is bulky and cumbersome to install in an operative position on the crank pin.

Still another problem associated with my aforementioned crank pin grinding apparatus is that the stones are clamped in a split tool holder so that they can be changed only by disengaging a pair of clamping screws. It is therefore a rather laborious process to change the stones to accommodate different surface finishes and different crank pin lengths.

SUMMARY OF THE INVENTION The preferred embodiment of the present invention, which will be subsequently described in greater detail obviates the aforementioned problems in addition to providing some special advantages in crank pin grinding apparatus.

One major improvement in the preferred embodiment contemplates a quick-change tool holder comprising a pair of separable elements associated with each of the grinding stones. Each grinding stone is bonded to one tool holding element which is attached to its companion tool holding element through a spring loaded dovetail connection. The dovetail connection permits separation of two elements by the application of a slight disengaging force so that the grinding stone can be easily and quickly replaced.

The bearing surface of the crank pin is often finished 1n a two-part operation. First a rough-finish stone having a length shorter than the crank pin is stroked back and forth to remove scored and grooved sections. The roughfinish stone is then replaced by a smooth finish stone having a length corresponding to the length of the crank pin. The final finished surface is achieved by a single radial movement of the stones toward the bearing surface.

By eliminating the final stroking operation, two advantages are achieved: (1) a smaller surface thickness is removed so that the crank pin retains its heat-treat surface hardness, and (2) a true cylindrical bearing surface is obtained rather than the rounded surface commonly associated with a stroked finish.

The quick-change tool holder enables the operator to readily and easily change from a rough to a finish stone and to change stones to accommodate crank pins of variable lengths.

A second feature of the preferred embodiment of the present invention contemplates a flexible drive shaft providing an operative connection between the output of the drive motor and the tool rotating mechanism. This feature of the present invention provides two advantages over the grinding apparatus of my aforementioned patent. First, since the housing supporting the annular ring is separate from the motor housing, the grinding apparatus provides a much smaller unit thus increasing the facility with which the apparatus can be attached to a crank pin and moved between a series of crank pins.

The drive motor is clamped to a fixed part of the vehicle carrying the engine. The flexible shaft provides an important second advantage in that once the motor is clamped to the vehicle frame, the operator need manipulate only the weight of the grinding apparatus as it is repositioned from crank pin to crank pin.

The preferred grinding apparatus of the present invention is provided with a pair of extensible arm assemblies,

each arm assembly comprising a pair of companion slide members. One member of each slide assembly is attached to the housing and the other slide member carries a roller member supported for rotation about an axis perpendicular to the axis of the crank pin. A bracket associated with each arm assembly is attached to the crankcase housing and provides a guideway parallel to the longitudinal axis of the crank pin. The roller members of the arm assemblies ride in the guideways so that the grinding apparatus is guided for movement along the true axis of the crank pin during a stroking operation. The pair of extensible arm assemblies also cooperate to absorb reaction forces developed by the grinding stones rotating about the crank pm.

The preferred grinding apparatus is provided with optional means for advancing the stones against the crank pin including an automatic feed-in mechanism and a manual feed in mechanism. Both feed devices utilize a first member carried by the stone carrying ring and a second member supported by the fixed housing supporting the ring.

The automatic feed mechanism utilizes a second member taking the form of a resilient finger which intermittently engages a gear carried by the ring. The gear is coupled to the stone holders so that rotation of the gear advances the stones. The resilient finger has a selected stiffness to rotate the gear if the stones are not in contact 3 with the bearing surface and to ride over the gear if the stones are bearing against the bearing surface.

The manual feed device utilizes a threaded member supported by the housing and movable into frictional engagement with a second ring member carried by the ring. The second ring is coupled to the stones so that the frictional engagement produces a relative movement between the main ring member and the second ring operable to advance the stones.

Another feature of the preferred grinding apparatus illustrating the present invention takes the form of a dressing attachment for the grinding stones. The dressing apparatus is clamped to the housing of the grinding apparatus and preferably includes a diamond dressing tool supported for movement in an axial direction within the tool holding ring. An elongated feed member provides means for advancing the dressing tool in surface finishing contact with the grinding faces of the stones while the stones are rotated by the grinding motor. Thus the grinding stones can be finished to a true contour corresponding to the peripheral surface of their associated crank pin. This dressing operation can be accomplished in a manner of minutes without even removing the stones from their holders and by taking advantage of the drive means associated with the grinding apparatus.

It is therefore an object of the present invention to provide a crank pin grinding apparatus having a pluraliy of annularly spaced grinding stones rotated in surface finishing contact about the crank pin bearing surface and including a quick-disconnect tool holder permitting an easy replacement of the grinding stones.

It is another object of the present invention to provide a grinding apparatus for crank pin bearing surfaces having a grinding stone rotated in surface-finishing relationship with the bearing surface while the crank pin is held stationary and wherein the grinding stone has a length corresponding to the length of the crank pin bearing surface.

Still another object of the present invention is to provide a grinding apparatus for finishing the bearing surfaces of crank pins while the crank shaft is supported in the engine and wherein a plurality of grinding stones are rotated around the bearing surface of the crank pin by an operative flexible connection between the apparatus and a remotely supported drive means.

A still further object of the present invention is to provide means for stabilizing a crank pin grinder adapted to be attached to a crank shaft journalled in it engine by providing a guideway fixed to the engine and a pair of spaced apart arm assemblies providing a connection between the apparatus and the engine for the transmission of reaction forces developed by the rotating grinding stones.

Still another object of the present invention is to provide means for dressing the stones of a motor driven grinding apparatus.

Still furtherobjects and advantages of the present invention will become apparent to those skilled in the art to which the invention pertains upon reference to the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS The description makes reference to the accompanying drawings in which like reference characters refer to like parts throughout the several views and in which:

FIG. 1 is a perspective view of a crank pin grinding apparatus illustrating apreferredembodiment of the invention and operatively connected to a drive motor through a flexible drive shaft;

FIG. 2 is an enlarged fragmentary sectional view taken along line 2-2 of FIG. 1;

FIG. 3 is an enlarged view taken along line 3-3 of FIG. 2;. I

FIG. 4 as a sectional view through one of the extensible slide assemblies and taken along line 4--4 of FIG. 1;

FIG. 5 is an elevational view of the two halves of the tool holding ring separated one from the other;

FIG. 6is an enlarged view taken along line 6--6 of FIG. 5;

FIG. 7 is a transverse sectional view of the assembly showing the worm gear connection between the flexible shaft and the annular ring;

FIG. 8 is an enlarged fragmentary view of the automatic indexing member;

FIG. 9 is an elevational side view of the grinding apparatus illustrated in FIG. 1 with parts in section for purpose of clarity;

FIG. 10 is a view illustrating a tool for manually moving the grinding stones into a grinding position with the bearing surface of the crank pin;

FIG. 11 is a perspective view of a preferred dressing apparatus attached to the preferred grinding apparatus for truing the grinding stones.

FIG. 12 is an elevational view of the grinding and dressing apparatus combination illustrated in FIG. 11;

FIG. 13 is a side elevational view of an apparatus illustrated in FIG. 11 with parts in section for purposes of description;

FIG. 14 is a fragmentary view of a scale means for providing an indication of the grinding progress; and

FIG. 15 illustrates the hand operated friction device for advancing the grinding stones against the crank pin bearing surface.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, FIG. 1 illustrates a grinding apparatus 10 operatively connected to a motor 12 through a flexible, elongated, drive shaft 14 and a chuck 16. The grinding operation is described with reference to a crankshaft journalled in an engine, a part of which is illustrated in phantom at 18. The engine 18 is carried by a vehicle having a frame member 20 remote from the engine. The motor 12 is adapted for an electrical connection and fixed to the frame member 20 by clamping means 22.

The grinding apparatus 10 includes an upper semicircular housing section 24 and a lower semi-circular companion housing section 26 pivotally connected to housing section 24 by a pin 28. The separable end sections of the housing sections 24 and 26 are flanged as illustrated, with a threaded fastener 30 carried by lower housing section 26 adapted for a threaded connection with the upper housing section 24.

As can best be seen in FIG. 9, an annular inwardly facing recess 32 is defined in the housing sections 24 and 26. The recess 32 provides a bearing surface for annular ring assembly 34. The ring assembly 34 is intended to rotate within the closed housing halves 24 and 26-.

Referring to FIG. 5, the ring assembly 34 comprises a pair of companion ring halves 36 and 38. The ring halves 36 and 38 are similar to one another with the exception that ring half 38 carries a pair of pins 40 and the ring half 36 is provided with a pair of sockets 42 intended to receive the pins 40. The pins 40 have a length slightly less than the depth of the sockets 42 so that the ring halves 36 and 38 may be mated one to the other to provide a circular ring assembly 34. The ring half 36 is provided with a pair of bores 44 each of which intersects a socket 42 such that their axes are in a perpendicular relationship and slightly spaced one from the other. The pins 40 are each provided with an arcuate cut-out 46 which registers with the bores 44 when the pins 40 have been received by their respective sockets 42. A locking pin 48 is associated with each of the bores 44 and is provided with an eccentric locking portion 49 formed on an axis offset relative to the body of the pin. A cut-out 50, formed in locking portion 49 is shaped to correspond to the circumference of the sockets 42.

In order to mate the ring halves 36 and 38 one to the other, the pins 48 are inserted in their respective bores and rotated so that their cut-out portions 50 register in the position illustrated in FIG. 6 so that the pins 40 can be received by their respective sockets 42. The pins 48 are then rotated so that the eccentric portions 49 are tightly wedged in their respective bores 44 thereby rigidly locking the ring halves 36 and 38 together. The rings 36 and 38 can be separated merely by rotating the locking pins 84 so that the eccentric portion 49 of the pin moves out of registry with the cut-out 46 of the pins 40.

The circumferential edge of the rin assembly 34 is provided with teeth 52 which mesh with a worm gear 54 which as can best be seen in FIG. 5 is journalled in a housing 56 carried at the periphery of the lower housing 26. The worm gear 54 is operably connected to the flexible drive shaft 14. Thus rotation of the drive shaft .14 produces rotation of the ring assembly 34 within the housing halves 24 and 26.

It can therefore be seen that the purpose for the split gear assembly 34 is to permit the ring halves 36 and 38 to be positioned around a crank pin, locked together and setted for rotation in the hinged housing halves 24 and 2 As FIG. 9 best illustrates, a split annular plate 58 is fastened to one face of the ring assembly 34 and a second annular plate 60 is fastened to the opposite face of the ring assembly 34, preferably by threaded fasteners 62.

The ring 34 is provided with an annular slot 64 on the face associated with the annular plate 60. The outer periphery of the plate 60 overfiaps the slot 64 to provide a seat for a split' bevel gear 66. The gear member 66 is provided with an annular series of teeth 68 which rotate in the slot 64. It is to be understood that the annular gear 66 can rotate relative to the gear assembly 34.

Now referring to FIGS. 2, 3 and 5, the ring assembly 34 carries a plurality of annularly spaced grinding tool holders generally indicated at 70. Each tool holder 70 includes a bevel gear 72 seated in a slot 74 provided in the ring gear 34. The slots support the bevel gear 72 for rotation about an axis radial to the axis of the ring gear 34. A radially outwardly directed socket 76 extends from each of the slots 74. A sleeve member 78 provided with a head section 80 is seated in each gear 72 so that the sleeve extends through the gear for a sliding fit in the socket 76. The sleeve is splined as at 82 to fit with a com plementarily splined bore in the gear 72.

An elongated hollow stud member 84 is threadably engaged with the bore of the sleeve 78 and has a female tool holder 86 fixed at its inner end. Thus rotation of the gear 72 produces movement of the stud 84 between an extended position wherein it projects toward the axis of the ring assembly and a retracted position wherein it is received within the sleeve 78.

The female coupling 86 is provided with a slot 88 having divergent sides. A male coupling member 90 is provided with a tongue section 92 complementarily formed to the slot 88 and adapted to slidably engage therewith. A grinding stone 94 is preferably bonded to the inner face of the male coupling 90 and is provided with an arcuate grinding face 96 having a contour corresponding to the desired circumference of the crank pin. The stud 84 has a longitudinal threaded bore 98 which registers with a bore 100 formed in the male coupling 86. The inner end of the bore 100 terminates at the base of the slot 88. A seat 102 formed in the tongue 92 of the male coupling member 90 registers with the bore 100 when the coupling members 86 and 90 are in their fully engaged position.

A ball 104 slidably disposed in the bore 98 is urged toward the couplin member 90 by a spring biased member 106 which reacts against a threaded plug 108 carried in the threaded bore 98. The tension of the spring 106 can be adjusted by moving the plug 108 toward or away from the ball 104. The plug 108 is locked in place by a locking screw 110.

Thus, it can be seen that when the coupling members 86 and are in their fully engaged position, that the ball 104 emerges from the bore sufiiciently to seat in the seat 102 so that relative movement between the coupling members 86 and 90 is restricted. However, by applying a slight force on the male coupling member 90 to produce relative movement with member 86, the ball 104 can be unseated to permit disengagement of the coupling members.

As can best be seen in FIG. 2, it is intended that the finish grinding stone 94 has a length corresponding to the length of the gearing surface of the crank pin 112. The quick disconnect coupling members 86 and 90 permit the stone to be quickly interchanged with a different stone such as a rough finish stone (not shown).

As thus far described, it can be seen that rotation of the gear 72 moves the grinding face 96 of the grinding stone 94 toward or away from a radial position corresponding to the surface of the crank pin 112. The bevel gear 72 as can best be seen in FIG. 2 is in mesh with the teeth 68 of the ring gear 66. Thus, relative rotational movement between the gear 66 and the ring assembly 34 produces a corresponding rotation of the gear 72. Referring to FIGS. 1 and 9, the inner peripheral edge of the ring gear 66 is provided with teeth 112 which mesh with a gear 114 which is supported for rotation by a pin 116 journalled in the gear assembly 34. The opposite end of the pin 116 carries a gear 118 which is associated with the split annular plate 58.

Referring to FIG. 8, upper housing section 24 carries a spring-loaded plunger 120. The plunger 120 carries an inwardly directed resiliently supported finger 122 which is movable between an extended position wherein it engages the gear 118 and a retracted position wherein it clears the gear 118. The plunger 120 is disposed in a housing 124 and its outer portion carries a pin 126 which registers in a slot 128. In the extended position of the plunger 120, the pin 126 is received by the slot 128; in the retracted position, the pin 126 is withdrawn from the slot and rotated 90 to seat on the end of housing 124.

Now the grinder as thus far described, operates as follows: The output of the motor 12 by means of the flexible shaft 14 produces rotation of the ring gear assembly 34 within the housing sections 24 and 26. The gear assembly 34 rotates the ring gear 66 and the gear 118 until the gear 118 engages the finger 122. If the grinding stones 94 are not in surface finishing contact with the crank pin, the finger 122 causes the gear 118 to rotate by one tooth which in turn rotates the gear 114 and produces relative rotation between the ring gear 66 and the ring assembly 34. Thus relative rotation between the ring gear 66 and the ring 34 rotates bevel gears 72 to produce a simultaneous radially inward displacement of the grinding stones 94. If the grinding stones 94 are in abutment with the crank pin when the gear 118 orbits into a meshing relationship with the finger 122, the plunger retracts sufficiently to permit the continued travel of the gear 118 without causing it to rotate. Thus it can be seen that as the stones gradually reduce the diameter of the crank pin journal 112, that the stones are progressively indexed radially inwardly so that they are at all time in surface-finishing relationship with the gearing surface of the crank pin 112.

When the grinding apparatus 10 is first positioned around the crank pin 112, the stones 94 are moved inwardly from their retracted position toward the surface of the crank pin 112 by a tool 130, illustrated in FIG. 10 which engages a socket 132, illustrated in FIG. 1, so that a toothed section of the tool 130 meshes with the ring gear 66. Rotation of the tool 130 provides means for manually indexing the stones 94 into abutment with the bearing surface of the crank pin 112.

Now referring to FIG. 2, each of the female coupling members 86 is provided with a pin 134 in registry with a slot 136 provided in the annular plate 58. The slot 136 is radially formed to permit the coupling 86 to move between its fully extended and retracted positions, but prevents rotation of the coupling 86 relative to the ring 34. The pins 134 thus insure that once the stones 94 have been positioned at an equal radial distance from the axis of the ring gear 34 that they will move in unison toward their grinding position.

Now referring to FIGS. 1 and 4, a pair of male slide members 138 are fixed to opposite sides of the housing 56. A companion female slide member 140 provided with a slot 142 is slidably engaged with a complementarily formed tongue 144 of the slide 138. The slides 138 are each provided with a series of longitudinally spaced threaded bores 146. The female slide 140 is provided with a longitudinal slot 148 which receives plurality of threaded fasteners 150 for threadable engagement with the bores 146 to lock the slides 138 and 140 to one another at a selected relative position.

A support member 152 is fixed to the end of each of the slide members 140 and carries a roller member 154. The rollers 154 are supported for rotation about an axis preferably parallel to the direction of the relative movement between the slides 138 and 140.

An elongated bracket 156 is associated with each of the rollers 154 and fastened preferably to the block of the engine 18. Elongated slots 158 permit the brackets 156 to be attached to the engine 118 by using the same holes that accommodate the bolts that hold the oil pan (not shown). Each pair of brackets 156 are arranged such that C-shaped guideways 160 are in alignment with one another and provide a guideway fer the rollers 154 in a direction parallel to the axis of the crank pin 112. This alignment is achieved because of the fact that the surface of the engine block that accommodates the oil pin is normally parallel to the axis of the crankshaft. The pair of rollers 154 also stabilize the grinding apparatus when the grinding stones 94 are rotating about the hearing surface of the crank pin 112 by transmitting the torque developed by the grinding stones 94 to the engine block.

The comparison slide members 138 and 140 provide an extensible arm assembly to accommodate a variable dis tance between the bracket 116 and the centeriine of the crank pin 112.

Now referring to FIGS. 11, 12 and 13, a dressing apparatus generally indicated at 162 is adapted for attachment to the housing 56 so that the stones 94 may be resurfaced in place. The dressing apparatus includes a pair of support members 164 each of which is attached to the male slide members 138 by a threaded fastener 166. The support elements 164 each have an upright supporting section 168 which define a pair of axially aligned threaded bores 170 and a second pair of bores 172 "which are in spaced parallel relationship to the bores 170. The threaded bores 170 accommodate an elongated threaded feed member 174. An elongated tool supporting member 176 is axially slidably disposed in the bores 172. The outer end of the tool support 176 is provided with a slot 178 which slidably engages the periphery of a disc shaped member 180 carried at the end of the feed member 174. A handle member 182 is carried by the disc 180 such that the rotation of the handle 182 produces a corresponding rotation of the feed member 174. Rotation of the feed member 174 produces coacting longitudinal movement of the feed member 174 and the tool support 176.

A pin 184 supported by the outer support section 168 registers with a longitudinal slot 186 formed in the tool support 176 and prevents rotation of the tool support.

An elongated tool 188 is carried in a bore 190 formed in tool support 176 and locked at a selected extended length by a threaded fastener 192. Preferably a diamond dressing tip 194 is carried at the end of the tool 188. In operation, the diamond tip 194 is supported at a radial distance from the axis of rotation of the grinding stones 94 corresponding to the diameter of the crank pin 112 which the grinding stones are to accommodate. The tip 194 is longitudinally adjusted such that it will engage the edge of the face 96. The stones 94 are then rotated about their axis by energizing the motor 12 and the dressing tip 194 is advanced by rotating the handle 192 so that the dressing tip 194 travels from the leading edge to the trail- 'ng edge of the grinding faces 96. Thus it can be seen that the contour of the grinding face 96 of each of the grinding stones 94 can be dressed in place without separation from the grinding apparatus 10 and by using the driving motor 12 associated with the grinding apparatus, so that the dressing operation can be accomplished in a relatively short time.

FIG. 15 illustrates a hand-feed device associated with the preferred grinding apparatus for manually indexing the grinding stones 94 into abrasive contact with the crank pin bearing surface. As heretofore described, relative movement between the split bearing ring 66 and the ring assembly 34 produces inward movement of the grinding stones 94.

The device illustrated in FIG. 15 produces this relative movement by an elongated member 200 threadably supported in a boss 202 forming an integral part of housing section 24. A knurled knob 204 is carried at the outer end of the member 200. The inner end of member 200 is narrowed as at 206 and provided with an annular recess 208. A hronze tip 210 is bored to receive the narrowed end 206 and a pin 212 secures the tip 210 tn the end 206. This arrangement permits the member 200 to be rotated without providing a corresponding rotation of tip 210. Rotation of the member 200 forces the tip 210 into a frictional engagement with the outer periphery of split ring 66. By applying a sufiicient pressure against the ring 66, the tip 210 produces a braking effect on the ring effective to produce relative movement between the rotating ring 66 and the rotating ring assembly 34 so that the grinding stones 94 move toward the bearing surface of the crank pin.

FIG. 14 illustrates how the gear member 66 may -be provided with suitable graduation 208 with a pointer 210 mounted on gear assembly 34 to provide the operator with an indication of the progress of the grinding. Preferably a full revolution of gear member 66 relative to gear assembly 34 produces a .250 inch displacement of the grinding stones 94.

It is to be understood that although I have described but one preferred embodiment of the present invention, that various modifications and revisions can be made therein without departing from the spirit of the invention as expressed in the scope of the appended claims.

What I claim is:

1. Apparatus for refinishing the bearing surface of the crank pin of a crankshaft while said crankshaft is stationary, comprising:

(a) an annular ring adapted for positioning around said crank pin;

(b) a plurality of annularly spaced tool holders coupled to said annular ring;

(c) a grinding element releasably carried by each of said tool holders, each of said grinding elements having an inwardly directed grinding face;

(d) drive means coupled to said annular ring to pro= vide rotational movement of said ring around the bearing surface of a crank pin so that said grinding elements rotate about the axis of said crank pin;

(e) means for simultaneously advancing said grinding elements radiaily inwardly in coacting relationship with the rotational movement of said ring so that said grinding faces are in surface finishing contact with the bearing surface of said crank pin;

(f) said crankshaft being journaled in an engine having a housing, and including means associated with said engine housing defining a reference axis parallel to the true axis of said crank pin, and means providing a connection between said reference axis and said annular ring so that said grinding elements rotate about an axis common to the true axis of said crank pin during a stroking operation;

(g) said apparatus including an annular housing, said ring being disposed in said housing and having teeth defined along its circumferential surface, a worm gear journalled in said housing and meshed with said teeth, a motor, and means providing a flexible, remote torque transmitting connection between the output of said motor and said worm;

(h) said connection-means accommodating a selected spacing between said reference axis and said crank pin, said connection means comprising:

a guide member attached to said engine housing,

said guide member defining an elongated guideway running parallel to the axis of said crank P a slide assembly providing an extensible connection between said annular housing and said guide member, said slide assembly including:

( 1) a pair of elongated, companion slide members, one of said slide members attached to said annular housing;

(2) a roller member carried by the opposite of said slide members, said roller member supported for rotation about an axis parallel to the direction of relative movement of said slide members; and said roller member slidable disposed in said elongated guideway; and

(3) means for locking said companion slide members, one to the other, at a selected length accommodating the spacing between said reference axis and said crank pin.

2. The apparatus as defined in claim 1, including a second guide member attached to said engine housing, said second guide member defining a second guideway forming an extension of said first guideway; a second slide assembly providing an extensible connection between said annular housing and said second guide member, and said first and second slide assemblies cooperating to stabilize said apparatus when said grinding elements are being rotated about said crank pin bearing surface in surface finishing contact.

3. The apparatus as defined in claim 2, wherein said annular ring comprises a pair of halves, and said annular housing comprises a pair of cooperating sections hinged for relative movement permitting said annular housing to be positioned about said crank pin.

4. Apparatus for refinishing the bearing surface of the crank pin of a crankshaft while said crankshaft is stationary, comprising:

(a) an annular ring adapted for positioning around said crank pin;

(b) a plurality of annularly spaced tool holders coupled to said annular ring;

(c) a grinding element releasably carried by each of said tool holders, each of said grinding elements having an inwardly directed grinding face;

(d) drive means coupled to said annular ring to provide rotational movement of said ring around the bearing surface of a crank pin so that said grinding elements rotate about the axis of said crank pin;

(e) means for simultaneously advancing said grinding elements radially inwardly in coacting relationship with the rotational movement of said ring so that said grinding faces are in surface finishing contact with the bearing surface of said crank pin;

(f) means for maintaining said grinding elements in continual surface finishing contact with the bearing surface of said crank pin, said means comprising:

a housing supported against rotation, said housing defining a bearing portion for said annular said tool holders supported for radial inward movement toward said crank pin bearing surface;

means actuated by the relative movement between said annular ring and said housing for advancing said tool holders toward said crank pin bearing surface, comprising:

(1) an indexing gear member carried by said annular ring;

(2) means responsive to the rotation of said gear and operable to advance said tool holders, the advance of said tool holders being a function of the rotation of said gear;

(3) a finger member supported to said annular housing, said finger member engaging said gear member at intermittent intervals, said finger member effective to produce rotation of said gear member through a selected arc when said grinding elements are not in surface finishing contact with the bearing surface of said crank pin and ineffective to produce rotation of said gear member when said grinding elements are in said surface finishing contact.

5. The apparatus as defined in claim 4, wherein said finger member has a resilient section, said resilient section supported for engaging said indexing gear member, and said resilient section having a stiffness sufiicient to rotate said gear member when said grinding elements are not in said bearing surface finishing contact but said stiffness permitting said resilient section to ride over said gear when said grinding elements are in said bearing surface finishing contact.

6. Apparatus for refinishing the bearing surface of the crank pin of a crankshaft while said crankshaft is stationary, comprising:

(a) an annular ring adapted for positioning around said crank pin;

(b) a plurality of annularly spaced tool holders coupled to said annular ring;

(c) a grinding element releasably carried by each of said tool holders, each of said grinding elements having an inwardly directed grinding face;

(d) drive means coupled to said annular ring to provide rotational movement of said ring around the bearing surface of a crank pin so that said grinding elements rotate about the axis of said crank pin;

(e) means for simultaneously advancing said grinding elements radially inwardly in coacting relationship with the rotational movement of said ring so that said grinding faces are in surface finishing contact with the bearing surface of said crank pin;

(f) said advancing means including:

a housing supported against rotation, said housing defining a bearing portion for said annular ring;

said tool holders supported for radial inward movement toward said crank pin bearing surface;

means responsive to relative movement between said annular ring and said housing and operable to advance said tool holders toward said crank pin bearing surface, comprising:

( 1) a member carried by said annular ring and supported for movement relative to said annular ring;

( 2) means responsive to the movement of said member and operable to advance said tool holders toward said bearing surface;

(3) means supported to said housing and arranged to provide a selected frictional engagement with said member, said frictional engagement effective to produce movement of said member relative to said annular ring.

7. The apparatus as defined in claim 6, wherein said member comprises an annular member carried by said annular ring, said annular member having an annular sur- 1 1 face, and including a finger carried by said housing, said 729,329 finger supported for movement toward said annular sur- 2,001,497 face, said finger arranged to frictionally engage said annu- 2,162,187 lar surface when said annular ring is rotating and elfective to produce relative rotational displacement between said 5 annular member and said annular ring. 597,336

References Cited UNITED STATES PATENTS 2,571,779 10/1951 Stodgell.

s1 347 2,890,550 6/1959 Wickland s1 -347 12 5/ 1903 Griflin et al. 5/1935 Lawhorn et al. 6/1939 Tharp.

FOREIGN PATENTS 5/1934 Germany.

JAMES L. JONES, JR., Primary Examiner US. Cl. X.R.

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