USRE15190E - A cobpobation - Google Patents

Description

w. F. FRASER.

MECHANICAL MOVEMENT. APPLICATION FILED OCT, 20. i920.

Ressued Sept. 13, 1921.

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MECHANICAL MOVEMENT.

'APPLICATloN FILED ocT. 2o, 1920.

Reissued Sept. 13, 1921.

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w. F. FRASER. I

MECHANICAL MOVEMENT.

APPLICATION FILED OCT. 20. |920.

ReissuedvSept. 13, 1921.

INVENTOR Wagen T Fraser Cgfm ywrrNEssss L G. Sla/Mier? ATTO EY A ated use in operating UNITED STATES PATENT oEFlcE.

WARREN' F. FRASER, OF WESTBOBO, MASSACHUSETTS, ASSIGNOR, `BY' MESNE ASSIGN- MENTS, TO NORTON COMPANY, O F WORCESTER, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

MECHANICAL MOVEMENT.

Specification of Beissued Letters Patent. Rei

Original No. 1,883,142, dated October `29, 1918, Serial No. 207,042, tlled December 14, 1917. Application .for reissue led October 20, 1920. Serial No. 418,2405.

To all whom it may coment.'

Be it known that I, WARREN F. FRASER, a citizen of the United States of America, residing at Westboro, in the county of Worcester and State of Massachusetts, have in vented certain new and useful Improvements in Mechanical Movements, of which the following is a full, clear, and exact specification.

This invention relates to improvements in mechanical movements and more particularly to mechanical movements adapted for reci or carriages for grin ers and like machines.

. The object of the invention is to provide simple and positive means for operating the reciprocatory member in opposite directions and for quietly and automatically reversing the direction of movement thereof when the machine is being operatedat a high rate of speed.

Still another object of the invention involves the use of instrumentalities for neutralizing the action of the driving member upon the driven member immediately prior to the shifting of the clutch and immediately following the shifting of-.said clutch, so as'to produce a gradual reduction in the speed of the driven member and a gradual increase in the speed of said member without necessitatin any reduction in the speed of the initial driving instrumentalities, thus permitting the driv1ng member to be operat a much greater speed than is permissible with other types of grinders.

The invention consists in the combination and arrangement of parts, whereby the above objects and certain other objects hereinafter appearing may be attained, as set forth in the followingpspecification and particularly `pointed out in the clair/ns.

Referring to the drawings:

Fi re 1 is a side elevation of a portion of a grlnder with drivin means embodying this invention shown 1n connection therewith; 4

Fi 2 is a detail side view of portions of the c utch and worm shifting slide with the casing containing the spring actuated contact members for said clutch shifting means shown in section;

Fig. 3 is a section taken on the line 3 3 of Fig. 1, with certain parts shown in elevation;

rocatory work tables Fig. 4 is a detail sectional view taken on the line 4 4 of Fig. 3, certain parts in said view being shown in elevation;

Fig. 5 is a section taken on the line 5 5' of Fig.v 1;

Fig. 6 is a detail viewof a modified form of the clutch and worm shifting means;

Fig. 7 is an enlar ed perspective View of the c utch shifting ever.

Like numerals refer to like parts throughout the several views of the drawings.

Inthe drawings, 1 represents the frame of a grlnder. 2 is a reciprocatory work table superimposed on said frame and adapted to be operated by suitable'gearing, including a rack 3, secured underneath the under part of said table. A gear 4 is adapted to mesh with said rack and this gear is operatively connected with a ear 5, preferably a worm gear, by means o? an intermediate gear 41, which is adapted to b e rotated by said worm gear. The worm gear 5 is driven by a worm 6 engaging the teeth on the periphery of said worm.

The worm 6 is naled in suitable the grinder, one Slidably mounted secured to a shaft 7 jourbearings in the frame of of which is shown at 8. upon the shaft 7 but rotatable with said shaft is a clutch member 9 having teeth 10 and 11 disposedat opposite ends respectively of said clutch member. Loosely mounted upon said shaft 7 adjacent to the end of the clutch member having the teeth 10 thereon is a gear 12 which is arranged to mesh with a gear 13 fast upon a shaft 14 which, in the present case, is the driving shaft of the grinder, said driving shaft being journaled to rotate in suitable bearin one of which is shown at 15, Fig. 3, an on this shaft is a pulley 16 from which the shaft receives its motion.

The gear 12 has teeth 17 adapted tointerlock with thev teeth 10 of the clutch. member through said Loosely mounted ssued Sept. 13, 1921.

thus rotating the A keye22 prevents the rotation of the clutch' mem v. able guides and these teeth 19 are arranged to operate said clutch member in a reverse direction to that imparted by the teeth 17 The gear 18 meshes with .an intermediate ar 2O which, in turn, meshes with a gear 21 fast to the driving shaft 14 and the last mentioned train of gears is adapted to rotate the worm shaft 7, through the clutch member 9, in an `op osite direction to that imparted by the tram 'of gears 12 and 13.

r 9 relatively to said shaft 7 and ermits said clutch member to be moved o gitudinally of said shaft from the teeth 17 of. the gear 12 to the teeth 19 of the gear 18.

During rotation of the worm 6 in engagement with` said gear 5, the thrust of said worm is borne by suitable end thrust bearpreferably consisting of a sleevey 23,

which is mounted uponsaid shaft and slidv 'able in the bearing 8. Interposed between one end of the sleeve 23 and the worm 6 is a ball washer 24 and interposed between vthe opposite end of said sleeve 23 and the nut 25 securedto said shaft 7 is a second ball washer 26. The sleeve 23 is` slotted at 27 and receives a yoke 28 on the arm 29 secured to a slide 30 sldably mounted in suitj 31 on the framel, said slide be` ing preferably arranged at the front of said frame with the arm 29 extending through a slot 32 cut through said frame. Y

The slide 30 carrying the arm `29 is arranged to reciprocate in its guides 31 in a direction substantially parallel with the axis of the shaft 7 and for the purpose of neutralizing, at certain times in the operation of the machine, the. eiect of the worm 6 upon said gear 5. rllhe period when said neutralizing. effect takes place is governed by the movement of the table 2 'and is accomplished preferably by means of a cam member 33 which, in its preferred form,

embraces a ylever 34 ivoted at 35 to the axis of said shaft frame 1. This lever as two arms 36 and 37.` The arm 36 carries the cam member 33 embodying a cam slot 38,` adapted to receive a follower 39 carried by an arm` 40 upon the slide 30.

The normal position of the arm 36 on said lever 34 is substantially parallel with the axis of the shaft 7 and when in this position the follower 39 is adapted to rest in the middle portion 41 of the cam slot38, which portion'is substantially straight and extends approximately at right angles to the 7. The slot has two sections 42 and 43 extending in opposite directions from the` straightportion 41 there-` of, the section 42 extending awa from the pivot 35 of said lever ina gra ual curve, while the section 43 adually curvesinwardly from said straight portion toward said pivot 35. j

.'When said lever 34 is in its central Iposi- -formed in the c utch` member 92.

tion with the follower 39 in the straight or rest portion of the cam slot, the slide 30 will be prevented from moving longitudinally of the axis of the shaft 7 and consequently the entire movement of the worm 6 will be transmitted to the worm .gear 5. The other arm 37 of the lever 34 is constructed and arranged to engage adjustable abutments 44 and 45 carried by the table 2 which maybe adjusted to engage said lever at predetermined `periods in the operation of the machine and rock said lever in one direction or the other and during said rockin `movement, the follower 39 will enter eit er the section 42 or the section 43 of said cam` and be moved thereby to transmit a limited movement to the slide 30 longitudinally of the axis of the shaft 7.

The arm 37 of said lever 34 is adapted to be yieldingly maintained in its central position when not engaged by one or, the other of said abutments, preferably by means of pins 46 and 47 arranged upon opposite sides of said lever and adapted to engagea projection 48 on said arm. The pins 46 and 47 are each slidably mounted in brackets 49 and are yieldingly held in protruding relation to said brackets by` springs 50 arranged within said brackets and adapted to engage the shouldered portions 51 of said pins.

The springs 50 are adjusted so as to prevent any pressure being exerted b j said pins upon the projection 48 of'said ever when said lever 1S in its central position, but these springs will act as cushions for said lever when said lever is moved to 4one side or the other. The slide 30 is also arranged to accomplish the shifting of the clutch member 9 j and the means whereby this movement may be transmitted to said clutch member preferably 'embodies a clutch shifting lever 52 comprising a hub 53"'p`1voted at 53 to the frame of the machine and two arms 54 and 55, which are arranged substantially in alinement with each other, (seegFigs. 5 an 7). These arms 54 and 55 are preferably formed integral with the hub 53 `which is bored to receive the shaft constituting the pivot 53.

The arm 54. is a forked arm which engages a ring 56 arran ed in an annular groove 57 The other arm 55 of said lever has a stud 58 attached thereto, which projects through an opening 59 in the front wall of the frame 1 and betvlveen ak pair of oppositely disposed spring ble rackets 62 attached to the slide `30.

A spring 63 is interposed between theV rear end of each of the plungers 60 and 61 and the portion of the brackets 62 so as to exert a yielding pressure upon said plungers. The slide 30 has a recess 64 extending transversely therethrough at -the rear of the brackets containing the plungers 60k anl 61 and within rs 60 and 61 slidably mounted in suitn parts motion to the rack 3 this recess are pawls and 66 pivoted at 67 to the' front wall ofthe frame 1. The ends of the pawls 65 and 66 are adapted to engage a portiony 68 of the stud 58, said portion 68 of said stud being square for this purpose.

Stop pins 69 are provided for limiting the upward movements of said pawls and said pawls are adapted to be normally held in engagement with said stop pins, preferably by means of a spring 70 interposed between said awls and exerting equal pressure upon each. he ends of the ' awls 65 and 66 are positioned with relation to each other so that when one is holding said stud 58 in such a position that the clutch member 9 is in one of its operating positions, the endV ofv the other pawl will be deflected by said stud in readiness to engage said stud when the same is moved to the other clutch engaging position.

To actuate the vpawls 65 and 66 at the proper time to release the clutch operating lever, ins 71 and 72 are carriedby the slide 30-'an adapted to respectively engage the pawls 65 and 66 at the proper time in the operation of the slide.

The general operation of the machine hereinbefore specifically described is as follows: Assuming that the abutments 44 and 45 are adjusted roperly motion is imparted to the driving s iaft 14, thence throu h one or the other of the train of gears to t e worm shaft 7. The worm 6 transmits motion to the worm gear 5 and this motion may, in turn, be transmitted through a sliding clutch 73 which may be shifted by a hand lever 74 into engagement with the teeth 75 on said worm to a shaft 76, upon which said gear 5 isloosely pivotally mounted. The shaft 76 rotates the gear 4' and through the gear 4 imand incidentally the table. 2.

The direction in which said table will be moved at this time depends upon the position of the clutch member 9 and we will assume that said clutch member 9 is in engagement with the gear 18, thus said gear will impart a movement to the table 2 in the direction of the arrow a., Fig. 1. The movement of said table in the dlrection indicated continues until the abutment 44 engages the lever 34 and rocks said lever from the position shown in Fig. 1, which is the central position, into the position indicated in Fig. 4. y

This movement of said lever causes the section 42 of the cam 38 to act upon the follower 39 and force said follower to the right, as shown, moving with said follower theslide 30, and incidentally the sleeve 23 willbe moved in the same direction and cause the worm 6 and shaft 7 to be moved longitudinally of the axis of' thegshaft 7, thus neutralizing the ,effect of sa1d worm u on the ar 5, thereby reducing the speed 06 o the tab e 2 and finally stopping the movement of said table altogether, although said table is not stopped until the lever 34 'has y been rocked so as to bring the follower 39 to the end of the section 42 of the cam slot. Before the abutment 44 has engaged the lever 34 to rock the same about its pivot, the stud 58 .will be occupying the position shown in Fig. 2, at whlch t1me, as hereinbefore stated, the clutch member 9 is inits left hand position, with reference to Fig. ,5, and engaging the gear 18. The stud 58 will be held at this time in the position shown vin Fig. 2, by the pawl 65 which occupies the position illustrated in dotted lines, Fig. 4. As the slide 3() is moved in the direction of the arrow b by the section 42 of said cam 38, the bracket 62 will be moved therewith and the spring 63 at the rear of the plunger 61 will be compressed and thereby exert considerable pressure against the stud 58 which, at this time, prevented from moving by the pawl 65. As said slide approaches the extreme end of its movement, in the direction of the arrow b, the pin 71 carried thereby will engage the pawl 65 and trip the same, vthereby releasing the stud 58, permitting the spring to act through the plunger 61 and force said stud 58 to the position shown in full lines, Fig. 4, and simultaneously with the movement of said stud 58 the clutch member 9 will be disengaged from the gear 18 and moved into engagement with the gear 12.

At the time this change takes place, the effect of the worm 6 upon the gear 5 will 100 have been` neutralized so that said gear 5 and the train of gears connected therewith will come to rest and immediate] upon the shifting of the clutch member t e worm 6 will be rotated in an opposite direction.

When the worm starts rotating, the end thrust bearings will be permitted to move with the slide 30 until the follower 39 has moved from the end 42 of the slot 38, as shown in Fig. 4, to the straight portion of said slot, as shown in Fig. 1. This longitudidnal retreating movement of the continuously rotating worm, which initially equals the forward advance of the worm thread, is retarded adually as the cam follower rides along t e cam path, with the result that the worm wheel is gradually accelerated.

The longitudinal movement of the slide 30 and the worm will have dropped to zero 120 whenithe followerV hasr reached the straight portion of the cam and is directly 1n a plane parallel with the axis of the worm and containing the axis yof the cam lever. When this movement of said follower is taking place, the effect of said worm 6 upon the gear 5, owing to the pecullar shape of the slot section 42, will be to slowly st art the worm gear into operation in the direction of the arrow c, Fig. 4, and gradually 1n- 130 crease the speed thereof, thus reversing the direction of movement of the table 2, which movement will continue until the abutment 45 strikes the arm 37 and rocks said arm in the opposite direction.

As soon as the table 2 starts to operate in the direction of'the arrow d, which it does when the gear 5 is rotated in the direction of said arrow c, the y, abutment 44 will be withdrawn from the lever 34 and permit the springs 50, acting through the pins 46 and 47, to coperate with the section 42 to centralize the cani lever so as to retain said follower in said straight portion.

Furthermore, the movement of the slide 30 in the direction which results in the return of the follower 39 from the section 42 of the slot 38 to the straight portion thereof, causes the plunger 60 to engage the stud 58 and the springs 63 engaging` said lunger will be compressed in readiness to sliift the clutch when the stud 58 is again released, by the tripping of the pawl 66 throu h the instrumentalities of the pin 72 on sai slide 30. The reversing operation 4of the driving mechanism will be repeated just as long as the clutch 73 engagesthe worm ear5 and' power is supplied to the driving aft of the machine.

In Fig. 6 of the drawings I have` illustrated a modified form of cam. In this form 77 is, a slide arranged to reciprocate verticall in guides 78 attached to the frame 1 35 of t e machine. `This slide has a cam slot 79 consisting of a straight portion 80 and sec e tions`81 and 82 curving in opposite directions with re ect to a vertical plane passing through t 'ecenter of the straight portion 80 of said slot at right angles to the direction of movement of said slide. The follower39 of the slide 30 works in the cam slot 79 in substantially the same manner as in the previous case.

upper 'end in the path of abutments 84 and 85 which are adjustably mounted on the reciprocatory work` table 2 and mentsare beveled at 86 and in opposite' directions. The bevel of the abutment 84 v causes said slide 77 to be moved upwardly when it engages the cam roll 83 while the bevel 86 -of the abutment 85 engages said roll83 and causes the slide to be depressed, thus imparting a reciprocatory movement to said slide 30. i

The slide 77 has a projection 87 extending laterally therefrom which is interposed between two p said slide, and between opposite faces of said projection and portions ofy saidride are springs 88 and 9 constructed an arranged to centralize said slide whenpressure is removed therefrom and also to assist in returning said slide to its normal position.

worm 6, and cam' The Slide 77 has a m11 sa aaah-ed to as these ebutsections of one of' the guides foi?` Itv has been previously stated that the mechanism hereinbefore' described is particularly adapted for use in o rati the work table of a grinder but it w1 l be evident that `the mechanism is not limited toV this particular adaptation but -may be used in various other types of machines. Furthermore, the particular construction of tli'e present embodiment ofthe invention is but one of the many forms which may be employed, therefore the invention should not be considered as limited to this particular embodiment but other embodiments may be employed without departing from the spirit an scope of the invention, as definedin the nded` claims. aving thus speciicall vention what I claim an Patent to secure is:

1. In a machine havin a reciprocable table, a reciprocating mec anism therefor, comprising a ap f described my indesire by Letters driven member -operatively connected with said table, a driver therefor, drivin and reversingmechanism to move lthe driver in opposite directions to traverse 90 the table through a variable stroke, said driver being capable of a secondary movement which tends to neutralize its driving action upon the driven member, and positively actuated mechanism to cause such secondary movement and start and stop the table gradually at each reversal and to permit the table to be driven at a uniform rate between reversals.

2. In amachine tool, a reci rocable body 1D0 and driving and reversing mecanism therefor, comprisin forward and reverse drivers, means 'inc uding a shiftable member to connect said drivers alternately in operative relation with said bod to reciprocate the same through a variab e distance and positivel actuating mechanism to reduce the spee of said body by a predetermined gradual retardation. before said member is shifted. l .y

3. In a machine tool, a reci rocable body and driving and reversing mec anism therefor comprising forward and reverse driving members, means including a shiftable memi ber to connect said driving members alternatel in operative driving relation with said d to reciprocate the same fora variable period and positively actuating means to reduce the s eed of said body gradually before said "shi table member is moved and thereafter to start said body gradually from rest toits normal rate.

4. In a'machine tool, a reciy rocable body and drivin andreversin mec anism therefor comprising a rotata le driver, a member driven thereby and operatively connected with said body to reciprocate the same through a variable distance, said: driver and driven member being relatively movable to f vary the `rate of reciprocation, and positively actuating mechanism controlling said relative movement to stop and start said body dually for each reciprocation.

5. v`n a machine tool, a rec] rocable table and driving and reversing mec anism therefor comprising a driving worm and a worm gear meshing therewith which are relatively movable arallel with the worm axis to var for comprising a driving worm and a worm `fore the clutch is shifted and gear meshing therewith which are relatively movable arallel with the worm axis to vary the spec of the table, a clutch mechanism to reverse the direction of rotation of the worm and ositively actuating means controlling said) relative longitudinal movement to reduce speed of the table gradually bethereafter to start the table gradually from the rest to its normal rate. Y

7. `An apparatus of the class described having, in combination,a gear, driving means for sald gear rotating in engagement with the periphe thereof, a plate having a cam slot formedltlierein, a roll adapted to engage said slot, means operatively connecting sald roll with said driving means, and means for moving said plate to neutralize the effect of rections for variable periods,

said driving member upon said gear.

8. In a machine tool, a reciprocable table and a driving and reversing mechanism therefor comprising a4 rotatable driving worm which is movable longitudinally of its axis, a` worm gear meshing therewith and operatively connected with said table, means to rotate the worm in opposite directions for variable lengths of table traverse, and cam mechanism to move said worm axially, which is effective to stop and start the table gradually and to permit it to be driven at a normal rate for an indeterminate period.

9, In a machine having a reciprocable table, a worm gear operatively connected, with the table, a driving worm for said gear, means to rotate the worm in opposite dian end thrust bearing for said worm, and positively o rated means constructed and arrange .to move said end thrust bearing during the operation of the worm to neutralize the .effeet of the worm upon said gear and brmg the table gradually to a stop.

10. An apparatus of the class describedhaving, in combination, atable, means for reciprocating said table including a gear, a wo'rm ada'ptedto rotate said gear, an-end thrust bearlng for said worm, and means operated by said table adaptedto move said 5 end thrust bearing during the operation of said worm to neutralize the effect of said worm upon said gear. a

'11. In a machine tool having a reciprocable table, lmeans to reciprocate the same comprising relatively movable driving and driven members, a cam controlling the operative relation of said stop the table gradually, ated by movement of the the cam and effect an tion of the table.

12. An apparatvs of the class described having, in combination, a table, means for reciprocating said table includlng a rotatable driving member operatively connected therewith, a clutch to rotate said member in. opposite direcand means'opertable to actuate easy reversal 1n direcmembers to start and y adapted to be operated tions, means operated by said table adapted to move said member longitudinally of its axls to neutralize the effect of said member upon said table, and means operated by said member to shi-ft said clutch and reverse the direction of travel of the table.

13. An apparatus of the class described having, in combination, a table, means for reciprocating said table including a gear, a worm adapted to rotate said gear, a clutch adapted to be operated to rotate said worm in opposite directions, means operated by said table adapted to move said worm longitudinally of its axis to neutralize the effect of said worm upon said gear, and means operated by said worm moving means during the neutralizin action thereof, adapted to shift said clutc and reverse the -action'of said worm.

14. An apparatus of the class described having, in combination, a table, means for reciprocating said table including a gear, a worm adapted to rotate said gear, means for reversing the action of said worm, a movable frame, an end thrust bearing for said worm carried by said frame, and means operated by said table adapted to move said frame and said thrust bearing in a direc-` tion reverse to that of said gear, whereby the effect of said worm on said gear'will be neutralized.

15. An apparatus of the class described having, in combination, a reciprocating member, means for reciprocating said member including a gear, a worm adapted to rotate said gear, a pivoted cam, a slide adapted to be reciprocated by said cam, means carried by said reciprocating member adapted to rock said cam on its'pivot, means carried by said slide adapted tomove said worm longitudinally of its axis to neutralize the eilect of said worm upon said gear, means for rotatin said worm in opposite directions, a clutc adapted to be shifted from one of said worm rotating means to the other to reverse the action of said worm,

shift said clutch.

' mediately prior to the shifting of said clutch i and for acceleratin the speed of said geark worm ywith one or the other of `said driving Vdriving means or with said reverse driving means, and'means operated by `said reciprocating member adapted to shift said clutch from one of said driving means to the other and for reducing the speed of said gear 'imimmediately following the shifting of said clutch. y

17. An apparatus of the cla described having, in combination, a gear, a worm adapted to rotate said gear, forward and reverse driving means for said worm, ymeans to automatically shift from one of'said driving means to t e other, and means adapted to gradually reduce the speed of said gear prior to the shift vfrom one of said driving means to the other and to gradually accelerate the speed of said gear immediately following said shift. y

v 18. An apparatusof the'class described having,"iii combination, a gear, a worm adapted 'to rotateY said gear, forward and' reverse driving means for said worm, a clutch adapted to operatively connect said means, means for automaticall shifting said clutch, and means for gra ually neutralizing the effect of said worm upon said gear and thereby reduce the speed of said gear immediately prioryto the shifting of said clutch.-

19. An apparatus of the class described having, in combination, a gear, a worm f adapted to rotate said gear, forward and reverse driving means for said worm, a clutch adapted to operatively connect said worm` with one orr the` other of said driving means, means for automaticall shifting said clutch, and means for gra ually neutralizing the effect of said worm upon said gear and thereby reduce the speed of said gear immediately prior to the shifting of said clutch, said means being also adapted to gradually accelerate the speed ofk said gear immediately 4following the shifting of saidiclutch.: n y

`20. An apparatus of the class describedhaving, in combination, a gear, a worm adapted to rotate said gear, forward and reverse driving means for said worm, a slide, means operated by said slide adapted to shift from one of said driving means to -the other, and a movable cam member move said slide in opposite adapted to be automaticall i operated to irections.

21. An apparatus of the class described forward and laico having, in combination, a table, means for reciprocating said table, including a gear, a worm adapted to rotate said gear, forward and reverse driving means for said worin, a clutch adapted to operatively connect one or the other ofy said driving means with said worm, a movable cam member adapted to be operated in opposite directions by said table,

connectin said cam member `withl said and means operatively worin an said clutch,`adapted to neutralize the effect of said worm upon said gear and shift said clutch. i

22. An. `apparatus of the class described having, in combination, a table, means for reciprocating said table, including a gear, a worm adapted to rotate said gear,` forward and reverse driving means for said worm, a clutch adapted to operatively connect one Vor the other of` said driving means with said worm, a movable cam member adapted to beoperatedin opposite directions by said table, means cam member in its central position, and means operatively connecting said cam member with said worm andsaid clutch, adapted to neutralize the effect of said worm upon said gear and shift said clutch.

23. An apparatus of the class described y, means for."

having, in combination, a table, reciprocating said table, including a gear, a worm adapted to rotateisaid gear, forward `and reverse driving means for said worm,

a clutch adapted to operatively connect one or the other of said driving means with said worm, a movable cam member adapted to be operated 'in opposite directions by said table, a pair of oppositely disposed spring actuated contact members, adapted to centralize said cam member, and means operatively connecting said cam member with said worm and said clutch, adapted to neutralize the effect of said worm upon 'said gear and shift said clutch.

24. An apparatus of the class described having in combination, a gear, a worm adapted to rotatesaid gear, forward and reverse drivingmeans for said worm,y a `clutch adapted to operatively connect said worm with one `or the other of said driving means, a slide, end thrust bearings for said worin for yieldingly maintaining said supported by said slide, means ada ted to automatically move 'said slide and sai worm in opposite directions, and yieldable means operatively connecting said slide with said clutch, adapted to shift said clutch in op` supported by said slide, means adapted to automatically move said slide and said worm 'y in opposite directions, clutch engaging means, and a pair of oppositel disposed s rin actuated members carrie by said sli e, apted to move said clutch engaging members in opposite directions to shift said clutch.

26. An apparatus of the class described having, in combination, a gear, a Worm adapted to rotate said gear, forward and reverse driving means for said worm, a clutch adapted to operatively connect said Worm with one or the other of said drivin means, a slide, end thrust bearings for sald Worm supported by said slide, means adapted to automatically move said slide and said worm in opposite directions, clutch engaging means, a pair of oppositely disposed spring actuated members carried by said slide, adapted to move said clutch engagin members in opposite directions to shi said clutch, means for locking said clutch in its operating `positions, and means operated by said slide adapted to release said clutch.

27. An apparatus ofthe class described having, in combination, a gear, a worm adapted-to operate said gear, a slide, a bear-vv ing supported by said slide, adapted to receive the end thrust upon said worm, .forward and reverse driving means for said Worm, a clutch adapted to operatively connect said worm with one or-the other of said driving means, a clutch lever, oppositely disposed spring actuated members carried by said slide, adapted to engage said clutch lever, means adapted t0 lock said clutch lever in its operating positions, means to automatically move said slide in opposite directions to apply tension to one or the other of said spring actuated members, and means actuated by said slide adapted to trip said clutch lever locking means and permit said spring actuated plunger to move said clutch lever to shift said clutch.

Signed at Westboro, Massachusetts, this 1st day of October, 1920.

, WARREN F. FRASER.

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