US1634386A - Driving connection - Google Patents

Description

- luy 5, 1927.Il

c. SCHRAMM E'r Al.

DRIVING CONNECTION 1924 4 sheets-sheet 1 Filed -June 4 nflfmmml z n lllrl.

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DRIVING CONNECTION Filed June 4. 1924 4 Sheelts-Sheet 2 INVENTHHSA W @ge/)M WK7N a iff/,

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DRIVING CONNECTION Filed June 4, 1924k 4 sheets-snaai 4 Patented July 5, 1927.

UNITED STATES 1,634,386 PATENT OFFICE.

CARL SCBRAIM, 0F WIE-ST HARTFORD, AND A:PAUL F. VOKAL, OF HARTFORD, CON- NECTICUT, ASSIGNORS T0 PRATT 85 WHITNEY COMPANY, OF NEW YORK, N. Y., A.

y CORPORATION OF NEW JERSEY.

DRIVING CONNECTION.

Application led`June 4,

Our invention relates to driving connections and particularly to driving connections for operating thread grinding machines.

One object of our invention is to provide a driving connection for a work carrying spindle and a lead screw that shall compensate for the back lash between the work spindle and the lead screw.

Another object of our invention is to provide a driving connection for a thread grinding machine that shall be provided with a loose connection so constructed as to compensate for back lash and insure correct relative position between the grinding wheel and the work when the work and the grinding wheel are axially moved relatively to each other in` either direction.

In many machines, it is essential to maintain the cutting tool and the work in correct relative position. Thus in grinding a thread, it is essential to maintain the rotating work or thread in a correct relative position with respect to the grinding wheel. In moving the work longitudinally past the grinding wheel, it is not diliicult to maintain the grinding wheel in correct position with respect to the threads being ground when the work is being moved in one direction past the grinding wheel. However, upon reversing the longitudinal movement of the work, the back lash in the driving connection between the work spindle andthe lead screw changes the relative position of the rot-ating work and the grinding wheel so as to require a resetting of the work and the wheel with respect to each other.

-In a machine constructed in accordance with our invention, a loose connection is provided between either the work carrying spindle or the lead screw to compensate for the back lash in thedriving connection serving to operate the machine. Preferably the loose connection is provided between the work carrying spindle and the driving connection. In practicing our invention, the loose' connection serves to prevent rotation of the work carrying spindle upon reversal in the direction of rotation4 of the spindle and the leadscrew until the lead screw has been rotated sutcient to take up all back lash in the driving connection. In the conl struction above set forth, it will be noted no means is usedv to prevent back lash but means is provided for compensating for the 1924. Serial No. 717,794.

' invention.

Fig. 2 is an end elevational view of the machine shown in Fig. 1.

Fig. 3 is a detail view illustrating the wheel dressing slide.

Fig. 4`is a detail view of the means for controlling the wheel feeding movements.

Fig. 5 isa view partially in section along the line 5 5. of Fig. 4.

Fig. 6 is a sectional view along theline -6 6 of Fig. 1. i

Fig. 7 is a sectional view along the line 7-7 of Fig. 6.

Fig. 8 is a sectional view through the loose connection shown in Fig. 1 between the work carrying spindle and the driving means.

Fig. 9"is a sectional view along the line 9--9 of Fig. 8.

Fig. 10 1s a detail view ofthe adjusting pin shown in Fig. 8.

Fig. 11 is a. view partially in section of a second loose connection adapted to be placed between the work carrying spindle and the driving mea-ns.

Fig. 12 is a sectional view along the line 12-12 of Fig. 11.

' Fig., 13 is a sectional view along the line 13-13 ofthe loose connection shown in Fig. 11.

Fig. 14 is a third and the preferred loose connection adapted to` be placed between the work carrying spindle and the driving means.

Fig. 15 is a sectional view along the line 15-15 of the driving connection shown in Fig.v 14.

Fig. 16 is a sectional'view along the line 16-16 of thc driving connection shown in Fig. 14.

Fig. 17 is a sectional view through the reversing mechanism.

Fig. 18 is a detail view of partsof the reversing mechanism in horizontal section.

Referring to the drawings, a thread Aor tap grinding machine is shown comprising a main frame 1 upon which is mounted a work `carrying carriage 2 and a wheel slide 3.

The carriage 2 is mounted upon suitable guides 4 and 5, and the sllde 3 is mounted upon suitable guides 6 and 7. -The carriage 2 carries a headstock 8, which is preferably fixed to the carriage 2, and a tailstock 9 which is adjustable along the carriage 2 on suitable guideways.

An auxiliary wheel slide 10 is supported 0n a suitable uideway in the slide 3, as best shown in ig. 3 of the drawings. A nut 11, which projects from the bottom of the auxiliary slide 10, engages a screw shaft 12. TheY screw shaft 12 serves to effect feedingl movement of the wheel slide 3. The auxiliary slide 10 is connected to the wheel slide 3 by means of a nut 13 and a screw shaft 14. The nut 13 is iixedly secured to the auxiliar slide 10 and engages the screw shaft 14 which is mounted on the wheel slide 3. Thus, it is apparent rotation of the screw shaft 12 serves to operate the wheel slide 3 through the nut 11, auxiliary slide 10, the nut 13 and the screw shaft 14. The screw shaft 14 is operated, in a manner to be hereinafter set forth, when the grinding wheel is being dressed.

The wheel slide 3 is provided with a' bracket 15 which serves to support a wheel supporting plate 16. The bracket 15 is provided with arcuate T-slots 17 which are en- 16 in any set position. The plate 16 is provided w1th suitable bearings for the wheel spindle 19. The spindle 19 carries a grind-- lng wheel 20 and a driving pulley 21. In the'above construction, it will be noted the plate 16 may be adjusted on the bracket 15 to angularly adjust the grinding wheel 20 with respect to the workbeing operated upon.

The pulley 21 is connected by a suitable belt 22 to a pulley 23 which is mounted on a power shaft 24. The be'lt 22 extends over two idler pulleys 25 which are mounted on the slide 3. A pulley 26, which is mounted on the main frame 1, is resiliently held in engagement with the belt 22 to take up any slack during the movement of the wheel slide with respect to the mai frame.

A dressing slide 27 is provlded for carrying a suitable dressing attachment to true the grinding wheel 20. The slide 27 is movable along a second slide 28 and may be locked to the second slide by means of a lever 29a. The movement of the slide 28 is controlled by a hand wheel 29. The hand wheel 29 not only serves to effect movement of the slides 28 and 27 for dressing the wheel but also serves to effect movement of the wheel slide 3 by means of the screw shaft 14. The hand wheel 29 is connected to a short shaft 30 having a bevel gear wheel 31 mounted thereon. The bevel gear'wheel 31 meshes with a bevel gear wheel 32 which is mounted on a shaft 33. The shaft 33 'earries aspur gear wheel 34 and is provided with screw threads 35 which engage a nut 36. The nut 36 is secured to the slide 28, as indicated on Fig. 2 of the drawings. The gear whe-el 34 is connected to a gear wheel 38 which is mounted on and secured to the screw shaft 14. The gearing between the shaft 33 and the shaft 14 is such as to effect a two to one movement between the slide 28 Iand the wheel slide 3. Thus, the dressing slide is moved twice as far as the wheel slide. Accordingly the grinding wheel 20 is always mamtamed in adjusted position with respect to the work being operated no matter the end thereof, meshes with a spiral gear wheel 45 which is mounted on a shaft 46. The shaft 46 is connected to a gear whec'l 47 by means of a suitable clutch 48. The clutch 48 iscontrolled by a handle 49 which is mounted on a lever 50. The lever 50 is pivoted at 51 and operates a lever 52 b v means of an arm 53. The lever 52 is pivotal'ly supported at 54 on the main frame 1 and engages a bell crank lever 55. The bell crank lever 55 is provided with a bifureated end ortion which engages a collar formed on t e clutch 48.

The gear wheel 47 meshes with a gear wheel 58 which is mounted on a shaft 59.

The shaft 59 is located directly above the Vwheel 65 which meshes with a gear wheel 66 on a short shaft 67. The'shaft 67 carries a pulley 68 for supplying power to rotate the Work carrying spindle and to effect movement of the work carrying carriage 2.

The gear wheel 47 not only meshes with the gear wheel 58 but also meshes with :114.20

gear Wheel 69 which is fixedly mounted on a shaft 70. The shaft 70 also carries agear wheel 71 which meshes with the -gear wheel 60 on the shaft 59. The gear wheel 71 is ixedly connected to the shaft 70 and is con-` nected to a ratchet wheel 72. Between the ratchet wheel 72 and the gear wheel 69, a cam drum 73 is loose'ly mounted on the shaft 70. The cam drum 73 has a pawl disk 74 secured to it adjacent to the ratchet wheel 72. The disk 74 carries a pawl member 75 which is adapted to engage the teeth on the ratchet wheel 72. A. spring member 76 is provided for exerting a force at all times tending to move the pawl 75 into enga ement with the teeth on the ratchet wheel 2. Two levers 77 and 78 which are located on opposite sides of the shaft 70 are provided for engaging the pawl 75 to move 1t out of engagement with the ratchet wheel. The levers 7 7-and 78 are respectively mounted on short shafts 79 and 80 which also carry levers 81 and 82. The levers 81 and 82 are joined by a spring member 83 which exerts a force tending to move the levers 77 and 78 in the path of movement of the pawl 75. One arm 84 of a bell crank lever 85 is disposed between the levers 81 and 82 and serves to operate the levers 81 and 82 in accordance with the movement of the'carriage 2. The bell crank lever 85 is connected by a reach rod 86 to a bell crank lever 87. The ,be'll crank lever 87 is o erated by two dogs 88l and 89 which are ad]ustably mounted on the' carriage 2. The dogs 88 and 89 serve to limit the' extent of movement of the carriage 2.

Assuming the lever 77 to be in .engagement with the pawl 75, as shown in Fig. 17 of the drawings, and the pawl to be held out of engagement with the ratchet wheel 72, the cam drum 73 is held stationary. However, upon engagement between the dog 89 and the bell crank lever 87, the arm 84 of the bell crank 85 engages. the lever 81 and moves the lever 77 out of engagement with the pawl 75. rI`he pawl 75 engages the teeth of the ratchet wheel 72 and accordingly the disk 74 and the cam drum.7 3 are rotated with the shaft 70. Such rotation of the disk 74 and the cam drum 73 continues until the pawl 75 is enga ed by the lever 78. The lever 78 moves t e pawl out of engagement with thel revent further movementv ratchet wheel to of the cam drum 3.

Upon engagement between the dog 88 and the bell crank lever 87 at the other end of the movement of the carriage 2, the lever l78 4is moved out of engagement with the pawl 75 to eEect a half rotation of the cam drum 73. This last movement of the cam drum is stopped by the lever 77 engaging the pawl 75 to disengage it from a ratchet wheel 72. The disk 74 is provided with two notches 92 which are fitted t'o a. spring pressed plunger 93 to prevent any retrograde movement of the disk 74 and the cam rum 73.

The cam drum 73 has a cam groove 94 formed therein which operates a'lever 95 to control the clutch mechanism 62. The clutch mechanism'62, as heretofore set forth, serves to connect either the gear wheel 58 or the gear wheel 60 to the shaft 59. By such ymeans it is apparent the pulley 68 is rotated in a clockwise or in a counterclockwise direcaround two idler pulleys 100 which are mounted on the carriage 2. -The shaft 98 carries a spiral gear wheel 101 which meshes with a spiral gear wheel 102 on a shaft 103. The shaft 103 carries a gear wheel 104 which, meshes with a gear wheel 105 on a shaft 106. The shaft 106 is connected through a. suitable lost motion connection 107 to the driving spindle 108. The shaft 103 also carries a pinion 109 which meshes .with a gear wheel 110. The gear wheel 110 meshes with a gear wheel 111. The gear wheel 111 is connected to a glear wheel 112 which ,meshes with gear w y connected to the lead screw 114 which efects movement of the carrial e 2.

Referring to Figs. 1, 6 an 7 of the drawings, the lead screw 114 is connected to the carriage 2 by means of a nut 115 which has a worm wheel 116 secured thereto. The worm wheel 116, which is lixedly connected to the nut 115, meshes with a worm 117. The worm 117 is formed on a shaft 118. The shaft 118 extends through the front of the machine and has a hand wheel 119 mounted thereon. The hand wheel 119 serves to effect adjustment 0f the carriage 2 with respect to the wheel 20 at will.

The lead screw 12, which operates the wheel slide 3, has a ear wheel 121 mounted on it, as shown in igs. 1,` 4 and 5 of the drawings.` The gear wheel 121 meshes with a pinion 122 on a short shaft 123. The shaft 123 carries a gear wheel 124 which meshes with a pinion 125 on a shaft 126. The shaft 126 carries a hand wheel 127 for effecting feeding movement of the wheel slide 3 at will. The shaft 126 also carries a ratchet wheel 128 and a three armed lever 129. One arm 130 of the flever 129 carries a pawl 131. A

second arm 132 of the lever carries a pawl 133 and a third arm 134 is connected b a link 135 to a bell crank lever 136. The ell crank lever 136 is operated by a plunger 137.

lThe plunger 137 is operated by means of a dog 138 which is adjustably mounted on the work carrying carriage 2. The dog 138 operates the plunger 137 at each reciprocation of the carriage 2 and accordingly effects an oscillating movement of. the three arm lever 129. If the pawl 131 is in engagement with the teeth of the ratchet wheel 128, an intermittent feeding movement of the wheel slide 3 will be effected. A shield 139, which is adjustable on the 'ratchetwheeh serves to limit the total feeding t0 any desired eel 113. The gear wheel 113 is fxedamount. The shield 139 extends over the teeth of the ratchet and prevents the pawl 131 from engaging the teeth when the wheel has been fed to a predetermined depth. The arm 132 carries a handle 140 for feeding by hand when so desired. The amount of feed eifectedby the arm 132 .may be controlled by means of a shield 141 which is supported on the main frame of the machine.

Referring to Figs. 1, 8, 9 and 10, one form of the loosev connection is illustrated for compensating for the back lash in the gearing connected tothe lead screw 114 and the work spindle 108. The shaft 106, which is connected to the work spindle 108 through the loose connection 107, projects through a sleeve 144 which is suitably secured to the headstock of the machine. Adjacent to the sleeve 144, an arm 1'45 is keyed to the shaft 106. The arm '145 carries a pin 146 which projects into position between two stop members 147 and 148. The two stop members are mounted on a cup-shaped member 149. The cup-shaped member 149 is keyed to the work carrying spindle 108 as shown in Fig. 8 of the drawings. The pin 146 is adjustable in the arm 145 and is held in any set position by means of two set screws 150. A collar 151, which is threadably connected to the sleeve 144, engages a notch in the pin 146 and serves to adjust the position of the pin in the arm 145. A set screw 152 is provided for holding the collar 151 in any set position on a sleeve 144. It may be noted that the pin 146 may be adjusted by means of the collar 151 even if the shaft 106 and the spindle 108, are in rotation.

The pin 146 is provided with a tapered surface 153 which is adapted to engage the stop member 147 and a straight surface 154 which is adapted to engage the stop member 148. The stop member 147 is adjustable in a slot 155 and is provided ywith a tapered surface `156 which isl adapted to engage the tapered surface 153 on the pin. The stop member 148 may be secured in any one of the holes 157 in the cup member 149 and is provided with a straight surface for engaging the straight surface 154 on the pin 146.

In the above construction, it will be noted, the work carrying spindle 108 is rotatedby the pin 146 engaging one of the stop members 147 or 148. Inasmueh as the pin 146 does not simultaneously engage the two stop members 147 and 148, it is apparent a reversal in the direction ofrotationiof the shaft 106 permits the driving connection to operate for a limited time before the work carrying spindle 108 is rotated. Thus, compensation is effected for the back lash between the lead screw 114 and t-he work spindle 108. The amount of loose connection between the shaft 106 and the work spindle 108 may be roughly adjusted by varying the position of the' two stop members 147 and 148. A fine adjustment of the 'loose connection may be 'effected by varying the position of the pin 146 in the arm 145.

Referring to Figs.' 11, 12 and 13 of the drawings a modification of our invention is illustrate The shaft 106 projects through a cup-shaped member v160 which is secured to the carriage 2. A hub member 161, which is suitably pinned to the shaft 106, is disposed adjacent the cup member 160 and has teeth 162 formed on its periphery. A spider member 163 carries a number of pairs of pinions 164 and 165. v Each pair of'pinions 164 and 165 are rotatably mounted on a shaft 166 which is suitably secured to the spider member 163. Each of the pinions 165 meshes with the teeth 162 formed on the hub member and with teeth 167 which are formed on the cup member 160. Each of the pinions 164 meshes with teeth which are formed on the inside periphery of a ring shaped worm wheel 168 and with teeth 169 which are formed on a hub member 170. The hub member 170 is rotatably mounted on the shaft'106 and carries a pin 171 which projects through a slot 17 2 which is formed in a second cup-shaped member 173. The cup-shaped member 173 is fixedly connected to the shaft 106. The ring shaped worm wheel 168 is located between and supported on the two cup members 160 and 173, as best shown in Fig. 11 of the drawings. The cupshaped member 173 carries a pin 175 which is located at the same distance from the shaft 106 as the pin 171 is located. The two pins 171 and 175 are adapted to engage an arcuated lug 176 which projects from a disk 177. The disk 177 is lixedly connected to the work carrying spindle108. A suitable Worm shaft 178 is provided for effecting operation of the worm Wheel 168. j

The pin 175 engages one end of the lug 176 to effect rotation of the spindle 108 in one direction and the other end of the lug 17 6 to effect rotation of the spindle in a reverse direction. The position of the pin 171 in the Slot 172 may be adjusted to provide any amount of loose connection between the shaft 106 and the work carrying spindle 108. When the worm shaft 178 and the Worm wheel 168 are held stationary, it is apparent the pin 171 rotates with the shaft 106. Such operation is apparent inasmuch as the cup-member 160 and the worm Wheel 168 are held stationary. The pinions 164 and 165 rotate at the same speed and consequently the hub member 170 is compelled to rotate at the same speed as the hub member 161. The rotation of the worm wheel 168 by the worm shaft 178 varies the position of the hub member 170 with respect to the hub member 161 and accordingly varies the position of the pin 171 in the slot 172. Referring again to 'Fi 8 of the drawings, a suitable brake or frlction device 179 pin 171 engages thev is mounted on the 'spindle 108 in' order to prevent any overtravel of the spindle whenever the direction of rotation thereof is reversed.

Referring to Figs. 14, 15 and 16 of the drawings, a third and the preferred form of loose connection is illustrated. A disk 180, which is keyed tothe shaft 106, is provided with two arcuated stop members' 181 and 182. The sto member 181 is formed integral with the isk 180 whereas the stop member 182 is adjustably secured to the disk by means of bolts 183. The bolts 183 project through a slot 184 formed in the disk 180 and the' stop member 182 is preferably fitted to a groove 185 in the disk. The end of the member 182 adjacent to the member 181 is provided with a surface 181a which is inclined with respect to the axis of the shaft.

The surface 186 of the stop member 181, which is adjacent to the stop member 182, is parallel with the axis of the shaft. The work spindle 108 carries a collar member 187 which is provided with a lug 188. The lug 188 projects between the two stop members 181 and 182 on the disk 180 as shown in Figs. 14 and 16 of the drawings. The surface of the lug 188 which engages the sto member 182 is inclined in accordance wit the inclination of the surface'181a of the stop member. The spindle 108 carries a disk 189 having two pins 190 rejecting therefrom. The pins 190 project t rough the collar member 187 and compel movement of the work carrying spindle 108 in accordance with the rotation of the collar member. An annular member 191, which is pivoted'at 192 on the carriage 2, is provided with shoes 1.93 which are litted to a groove 194 in the collar member 187 A worm segment 195, which is formed on the annular member 191, as shown in Fi 15 of the drawings, is in engagement wit a worm shaft 196. The worm shaft 196 serves to effect movement of the annular member 191. When the shaft 106 is rotating in one direction, the stop member 182 engages the lug 188 to elfect rotation of the work carrying spindle 108 and when the direction of rotation. of the shaft 106 is reversed, the stop member 181 engages the lug 188 to eli'ect rotation of the spindle 108. Accordingly a rough adjustment of the loose connection may be effected by adjusting the position of the stop member 182 with respect to the stop member 101. A finer adjustment of the loose connection is effected by varying the position of the lug 188 with respect to the stop members 181 and 182. The axial position of the lug 188 along the shaft 106 is varied by operating the worm shaft 196.

Modications in the mechanism and in the arrangement and location of parts maybe made within the spirit and scope of our invention and such modifications are intended to be covered by the appended claims.

What we claim is: j

1. In a machine, the combination with al lead screw, a spindle, and a train of gears for rotating said spindle and the lead screw in a forward and 1n a reverse direction, of means for so connecting the spindle to the train ofgearin@r as to insure a limited rotation of the lead screw prior ,'to the rotation of the spindle upon change in the operation of the gearing to change the direction of rotation of the lead screw and the spindle.

2. In a machine, the combination with a lead screw, a work spindle, a carriage for the work spindle, a lead screw for operating said carriage, and means comprising a train of ears for rotating said spindle and the lea screw in a forward and 1n a reverse direction, of means for so connectingA the s indle to said train of gears as to insure a imited rotation of the lead screw prior to the rotation of the spindle upon change in the operation of the train of gears to change the direction of rotation of the lead screw and the spindle.

3. In a machine, the combination with a lead screw, a carri e operated by vsaid lead screw, a work spin le mounted on said car-y riage, and means comprising a train of gears for rotating thespindle and the lead screw in aI forward and in a reverse direction, of a lost motion connection between the spindle and said train of gears to insure a limited rotation of the lead screw prior to the rotation of the spindle u on change in the operation of the traino gears to change the direction of rotation of the spindle and the lead screw, and means for l'varying the amount of said lost motion.

4. In a machine, the combination with a lead screw, a carriage operated by the lead screw, a work carrying spindle, and means comprising a train of gears for rotating the lead screw and the spindle in a forward and in a reverse direction, of a lost motion connection between said spindle and the gear train, and means for varying said tion connection to insure the rotation of the spindle and the lead screw in the same relation when rotating in a forward and in a reverse direction. l

5. In a machine, the combination with a lead screw, a carria e operated by the lead screw, a work spind e mounted, on said carriage, said spindle servin to carry a piece of work having a threa formed thereon, and means comprising a train of gears connected to the spindle and the lead screw for rotating them in timed relation, of a lost motion connection 'oined to the gear train, and means for adjusting said lost motion connection to compensate lfor the back lash in said gear 'train whereby the spindle and the lead screw may` be rotated in a forward 6. In a machine, the combination with two rotating members, and mechanism for rotating the two members in timed relation to each other and for rotating the members in a forward and -in a reverse direction, of a loose connection between one of the members and the said mechanism to compensate for the back lash in said mechanism upon reversal in the direction of rotation of the members.

y7. In a machine, the combination with a work carrying spindle and a lead screw for moving the work along a cutting tool, of a gear train for rotating the spindle and the screw in a forward an in a reverse direction, and a lost motion connection between one of said members and the gear train to compensate for the back lash in the gear train.

8. In a machine, the combination with a work carrying spindle and a lead screw for moving the work along a cutting tool, of a gear train for rotating the spindle and the screw in a forward and in a reverse direction, and a lost motion connection between the spindle and said train of gears to compensate for the back lash in the gear train.

9. In a machine, the combination with a wiork carrying spindle, a lead screw for effecting relative movement between the work and a cutting tool, and means comprising a train of gear wheels for rotating the work spindle and the lead screw in a forward and in a reverse direction, of a lost motion connection between said gear train and the spindle and lead screw to compensate for the back lash in the gear train, said connectionfcomprising a lug member located between two stop members.

10. In a machine, the combination with a work carrying spindle, a lead screw for effecting relative movement between the work and a cutting tool, and means comprising a train of gear wheels for rotating the work spindle and the lead screw in a forward and in a reverse direction, of a lost motion connection between said gear train and the spindle to compensate for the back lash in the gear train, said connection comprising a lug member located between two stop memlbers, and means for varying the relative position of the two stop members to vary the lost motion in said connection.

11. In a machine, the combination with a work carrying spindle, a lead screw for effecting relative movement between the work and a cutting tool,A and means comprising a train of gear wheels for rotating the work spindle and the lead screw in a forward and in a reverse direction, of a lost motion connection between said gear train and the spindle to compensate for the back lash in the gear train, said connection comprising a lug member located between two stop members,

and means for varying the position of the lug and for varying the relative position of the two stop members to Vary fthe lost motion in said connection.

12. In a machine, the combination with a work carrying'spindle, a lead screw for4 spindle axis and for varying the relative position of the two stop members to vary,

the amount of lost motion in the connection. 13. In a machine, the combination with a work carrying spindle, a lead screw for effecting relative movement between the work and a cutting tool, and means comprising a train of gear wheels for rotating the spindle and the lead screw in a forward and in a reverse direction, of a lost motion connection between the work spindle and the gear train to compensate for the back lash in the gear train, said connection comprising a lug rotating with the work spindle, two stop members rotating with said gear train and respectively located on opposite sides of the lug member, and means for varying the relative position of the two stop members and for varying the position of the lug along the spindle axis to vary the amount of lo motion in said connection.

14. In a machine, the combination with a work carrying spindle, a lead screw4 for effecting relative movement between the workand the cutting tool, and means comprising a'train of gear wheels for rotating the work spindle and the lead screw in a forward and in a reverse direction, of a lost motion connection between the work spindle and lthe gear train, said connection comprising a lug rotating with the work spindle and projecting between two stop members which rotate with said train of gear wheels, one of said stop members having a surface invarying the position of the lug along the clined with respect to the spindle axis for engaging a similar surface on the lug and ward and in a reverse direction, of a lost to the spindle axis for engaging a similar motion connection between the work spindle surface on said lug, and means for varying and the gear train, said connection compristhe relative position of the two stop meming a lug rotating with the work spindle bers and for varying the position of the lug 5 and projecting between two stop members to vary the amount of lost motion in said 15 which rotatewith said train of `gear wheels, connection. one of said stop members having` a surface In testimony whereof, we hereto atiix our inclined with respect to the spindle axis for signatures. engaging a similar surface on the lug and the CARL SCHRAMM.

10 other stop member having a surface parallel PAUL FRANK VOKAL.

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