US2599900A - Jack - Google Patents

Description

0. DONOHUE June 10, 195 2 JACK 3 Sheets-Sheet 1 Filed March 5, 1949 INVENTOR.

awe/a 0017a bug June 10, 1952 D'QNOHUE 2,599,900

JACK

Filed March 5, 1949 3 Sheets-Sheet 2 "llu. mum l.

IN V EN TOR. 0. W?" 00/70/70 e 0. DONOHUE June 10, 1952 JACK 5 Sheets-Sheet 3 Filed March 5, 1949 Patented June 10, 1952 UNITED STATES PATENT .oFFicsl V 7 Owen Donahue, Rego Paris N. Y;

' Application Marci r5, 1949; Serial No. 79,769 1 f 15 Claims. (01.254 95) This invention relates to jacks and, more particularly, to a jack including a 'novel 'high leverage exerting mechanical movement whereby the jack is particularly adapted for pulling up and straightening heavy plates in ship building or repair work, for wrecking operations, for railroad equipment lifting, for boiler making, for pulling posts, for gear pulling, and for many other operations requiring the exertion of greatforce within fairly limited confines.

In many operations, particularly shipbuilding and repair and boiler making, plate straighten.- ing and pulling of a pair of plates into surface contact are recurrent operations. These operations are effected by the use of straightening or pull-up bolts, which are engaged through the plate or plates and then pulled up. by a suitable jack or like mechanism to straighten or flatten the plates. The bolts carry nuts which are then tightened to hold the plates set until they are riveted or welded in place. V

Also,'in such operations as wrecking, repair of structural members, and the like, it is necessary to exert great force to separate a pair of riveted or welded members, or to straighten a bent or otherwise damaged structural member. These operations, too, require the exercise of great force on a relatively limited area.

To easily, cheaply and efiectively accomplish such operations as the foregoing, the jack of the present invention includes a base arranged to .bear against a support and a reciprocable slide which may have an interchangeable chuck at one end, for pulling operations, and a head at the other end for pushing or lifting operations; In the case of pull-up or straightening operations, the chuck is engaged with the pullup bolt extending through the member to be pulled up or straightened, a nut is screwed onto the bolt, and theend of the latter is then engaged in the quick release chuck on the slide. The jack includes ,novel mechanism for first rapidly elevating the slide to take up the slack between the jack and its load and then exert-'- ing great force on the slide to pull the bolt up tight. The nut is then tightened on the bolt and a quick release mechanism on the jack is operated to release the bolt, allowing the jack to be carried to the next pull-up location.

to effect relative movement of the slide and pinion. A spring biases the pinion upwardl'yso that, during the first movement, the pinion remains in its upward position and the slide is drawn up or moved outwardly to take up slack. As the resistance increases, the pinion rolls down the slideand, through a lever arrangement of high mechanical advantage, moves a pawl engaged with the ratchet teeth to force the slide outwardly. Automatically operating cam means prevent retrogression of the slide while'permitting the outward movement thereof. The cam release means also releases the pawl so thatthe slide can be quickly released when a pull-up? is completed.

In the case of lifting or pushingoperations, the base of the jack is placed on one member or a' supporting surface and the slideis rapidly extendedto engage, its 'outer head with the member to be pushed or lifted. As the jack mechanism is further operated, the high lever age mechanical movementexerts great pressure on the slide to force the latter outwardly with ahigh degree of force. vA novel use of the jack is' in pulling a-plug or stopper into a hole in a ships hull for salvage or rescue operations. I g H With the foregoing in mind, it is an object of the present invention to provide a mechanical jack having rapid slack take-up means capable of exerting great force when resistance to jack movement increases. 7

Another object of the invention i to provide such a jack having .quick' release means.

A further object of the invention is to provide such a jackparticularly adapted for use in pulling up. .or straightening structural members, or forliftingzor.forcing operations.

Yet, another object is to provide such a jack including novel quick release means for a. detachable operating handle. V

These, and other objects, advantages and novel features of the invention will be apparent from the following description and theaccompanying drawings. In the drawings:

Fig; 1 is a side elevation view of the jack in the retracted position arranged to "pull up a plate holding bolt, a side plate being removed to better illustrate the jackmechanism.

' Fig. 2 is a view similar to Fig. 1 showing the line 4-4 of Fig. 1.

4 Y J r. 2,599,900

3 Fig. is a vertical sectional view of a chuck arranged to grip the plate holding bolt.

Fig. 6 is a partial sectional view of the jack operating handle, showing the pawl mechanism.

While the jack is universally applicable to 4 Serial No. 79,770, filed March 5, 1949, for Plate Holding Bolt. Such bolt, which is indicatedas a whole at H! in Figs. 1 and 2, maybe used,

for example, to hold a pair of plates ll, |2 in tight surface engagement, being providedwithj at2| supported on legs 22, 22' and reciprocably mounting a slider having an interchangeable chuck on its lower endarran'gedto grip b'olt l9. Casing 2| contains novel, high leverage mechanism operable by a handle to force l2 by bolt l0. 7 More specifically, casing 2| includes a base 23 and side walls 24, 24 held in spaced paral lelism by studs l6 engaged in spacers 26. 7 Side walls 24, 24 have transversely aligned, facing vertical grooves or tracks formed by transverse- 1y spaced ribs or rails I"! (Fig. 3) and slidably receiving elongated 'ribs' |8' on opposite sides of slider 25. Duringoperation of the jack, slider 25 is reciprocated relative to base 23 and walls 24, being guidedand held in vertical alignslider 25 outwardly to effect a clamping of plates ment by the ribs |8 engaged in the grooves or slots in walls 24. I

The slider 25 has a lifting or pushing head 3| at its outer end, and the longitudinal edge adjacent handle 35 is formed with rack" teeth 32. The opposite longitudinal edge has 'inl wardly facing ratchet teeth 33'. Rack teeth 32 mesh with a pinion 34 keyed to a shaft 36 extending laterally through 'aligned longitudinal slots 31, 31 in walls 24. Handle 35 is'moun'ted on one end of shaft 36' in a manner described 34 is rotated clockwise, it wmron inwardly along rack teeth 32, carrying links 4| inwardly to swing levers clockwise.. Pin 42 carries a radially projecting pin 46 forming a seat for the outer end of a heavy'coilspring 41. The inner end of spring 41 is seated in a recess 48 in a 4 leg 22. Coil spring 41 biases pin 42, and thus mounted between walls 24 and providedvwithan 1 operating handle 6| and a projection 62 enthe jak.

gaged in a coil spring 63 which also is engaged with a projection 64 on pin 54. 0am 69 frictionally engages slide 25 and is designed that, as the slide moves inwardly, cam 60 is rotated clockwise to wedge more tightly against the slide and resist such inward movement. However, handle 6| may be operated to release cam 60 to permit inward movement of slide 25. When the handle, 6| is swung counterclockwise (Figs. 1 and 2); by a sharp blow of the hand, for example, the cam 66 is released and spring 63 is compressed to bias projection 64 and pin 54 clockwise. This swings dog 56 to engage pin 5*! and kick pawl 55 out of engagement with Themanner in which handle 35 is attached to'pinion shaft 36 is as follows. Referring to Figs. 1,3 and 6, shaft 36 has a ratchet wheel 66 normally clutched thereto and embraced by a bearing aperture 61 in the inner end of handle 35 (Fig. 6). A pawl 68 on handle 35 is biased by a spring 69 to engage the ratchet wheel teeth, andcarries a rod 1| having a slot- '|2 in its outer end. Slot 12. receives a pin 13 in a member '14 on the end of a bar 16 slidable in a groove 11 along an edge of handle 35-. A U-shape lever 15 is pivoted at 18 on handle 35 and biased outwardly by a spring 19, the inner end of lever 15 beingconnected by a pin 8| to the outer end of b'ar16. A lever retaining loop 82 on handle 35 may be used to'lock lever '15 against the handle. When lever 15 is pressed against the handle, bar 16 is drawn outwardly to pull p'awl 68 out of engagement with ratchet The clutch connection for ratchet 66 is also operated by lever '15. This includes an exten- SlOI'l 83 on lever 15 connected by a link 84 to an os'cillatable link 88 pivoted at'81' on' handle 35. A pair of curved clutch jaWs'85, 85 are pivotally mounted on handle 35' and arranged to b'e'swung toward and away from the axis of shaft 36". These jaws have slotsrfi'l' in their outer ends receiving pins 88 'orlink '86. Jaws 85'are tapered or wedge-shaped in transverse section, with their radially inner'edges being thinner than the outer edges. As the jaws 85 are moved toward each other, their wedge surfaces engage frictional clutch members (not shown). Such inward movement is efiected as lever 151s moved inwardly to swing link disenga es ratchet wheel 66 from shaft 36 so that pinion 34 is free to roll up slide 25 under the influence of spring 41.

Chuck 39 is shown I'noreindetail in Fig. 5 as comprising an upper member 9 having'a "1""- head 9'2 receivable in a suitable slot in the lower end of slide 25. A lower member 93 is threaded onto member 9|, and has a frusto=conical section 94.- section 94 embraces chuck jaws 95, 95 which are rfiounted 'on a member 96 carrying pins 91 projecting through slots in member 93 and having" a head 98 engaged in aguide recess 99 nie'rnber 9|. Springs [0| bias member 96 downwardly so that jaws 95 are forced toward each other by the Walls of section 94 to grip a boltin the chuck. Chuck 3D is interchangeably mounted in slide 25 so that smaller or larger or different types of chucks may be readily used with The, describ'edjack operates in the renown-1g manner inapull-up operation. Gain 60 is released by being swung counte'r-cloc'zkwise by a sharpinward blow of inward pressure against handle 6|, releasing pawl 55 *aspreviously described, and lever 15 is swung inwardly to release handle 35 and ratchet wheel 34 from shaft 36. Slide 25 is then moved inwardly to the position of Fig.1 and engaged with bolt l0, which has previously been inserted through plates Ii, [2 and has nut I3 screwed thereon. As the outer end of the bolt enters chuck 30, jaws 95 are moved inwardly and spread apart to receive bolt [0.

Lever 15 is released, clutching ratchet 66 to shaft 36 and engaging pawl 68 with the ratchet. As handle 35 is reciprocated, pinion 34 moves in an inward direction along slide 25. Actually, at the beginning of the jack operation, slide 25 moves outwardly so that the pinion remains stationary. As slide 25 meets increased resistance to outward movement, due to the head of bolt Ill bearing against the under plate, pinion 3'4 moves inwardly. This swings levers 45 clockwise, causin pawl 55 to force the slide outwardly and pull bolt in to clamp the plates against jack legs 22. Such movement continues until the plates are in unyielding surface engagement, at which time nut I3 is tightened.

The bolt is then released by first swinging lever 15 to declutch ratchet 66 allowing spring 41 to move pinion 34 outwardly. Cam lever Si is then swung inwardly, as described, to release cam '60 and disengage pawl '55 through the medium of dog 56. Slide 25 may then be pushed in to release clutch from bolt 10.

It will be noted that two actions are involved in moving slide 30, both having pronounced force exerting effects. As pinion 34 is rotated, spring 41 tends to prevent its inward movement, thereby effecting an outward movement of slide 25. Then, as the resistance increases, levers 45 are swun clockwise (Figs. 1 and 2) to force slide 25 outwardly through the medium of pawl 55. The tremendous mechanical advantage due to the ratio of long arms 43 of the levers to short arm's 5| thereof enables great force to be exerted on the slide.

While the jack has been described as applied to a pull-up operation, solely by way of specific example, it should be emphasized that this operation is exemplary only, and the jack may be used in forcing or lifting operations by engaging base 23 on one member or surface and moving slide 25 to brace head 3| against the other member. In lifting operations, the jack is particularly useful in railroad work, where small clearances are available and concentrated force is required. The jack may be easily transported by means of handles I00, I00 on walls 24.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the principles thereof, it should be understood that the invention may be otherwise embodied without departing from such principles.

What is claimed is:

1. In a jack, in combination, a base; a force exerting member reciprocably mounted on said base for movement inwardly and outwardly relative to said base; movable means engageable with said member to force the latter outwardly relative to said base; an operating element for said member directly engaged with said member and operable thereon to move said member outwardly; force transfer means interconnectin said movable means and said element for operation of said movable means by bodily inward displacement of said element relative to said base and substantially parallel to the direction of movement of said member; and means biasing said element outwardly relative to said base whereby, during actuation of said element to move said member outwardly relative to said base to take up slack between the jack and the load on the jack, said element will remain in the extended position outwardly relative to said baseand move said member outwardly relative to said base; said element, when said member encounters resistance, moving inwardly relative to said base and in a direction parallel to the direction of movement of said member to operate said movable means to force said member outwardly relative to said base.

2. In a jack, in combination, a base; a force exerting member reciprocably mounted on said base for movement inwardly and outwardly relative to said base; movable means engageable with said member to force the latter outwardly relative to said base; an operating element for said member directly engaged with said member and operable thereon to move said member outwardly; force transfer means interconnecting said movable means and said element for operation of said movable means by bodily inward dis-' placement of said element relative to said base and substantially parallel to the direction of movement of said member; means biasing said element outwardly relative to said base whereby, during actuation of said element to move said member outwardly relative to said base to take up slack between the jack and the load on the jack, said element will remain in the extended position outwardly relative to-said base, and move said member outwardly relative to said base; said element, when said member encounters resistance, moving inwardly relative to said base and in a direction parallel to the direction of movement of said member to operate said movable means to force said member outwardly relative to said base; and releasable means automatically restraining retrogression of said member inwardly toward said base while providing movement of said member outwardly relative to said base. i r

3. In a jack, in combination, a load bearing frame; a force exerting slide reciprocably mounted in said frame for movement inwardly and out wardly relative to said frame, and, having gear teeth extending therealong; a pinion engaged with said teeth and mounted in said frame for bodily movement in a direction parallel the direction of movement of said slide; mechanism for rotating said pinion; biasing means urging said pinion outwardly relative to said frame; and movable means, including lever means mouiited on said frame and operatively connected to said pinion, engageable with said slide and operable by bodily movement of said pinion inwardly relative to said frame to force said slide outwardly relative to said frame; said pinion, during initial rotation being maintained outwardly relative to said frame by said biasing means and moving said slide out- .wardly relative to said frame until the reaction of said slide on said pinion exceeds the force of said biasing means, and further rotation of said pinion thereupon effecting bodily movement of saidpinion inwardly relative to said frame to operate said movable means to force said slide outwardly relative to said frame.

4. In a jack, in combination, a load bearing frame; a force exerting slide reciprocably mounted in said frame for movement inwardly and outwardly relative to said frame, and having gear teeth extending therealong; a pinion engaged with said teeth and mounted insaid frame for bodily movement in a direction parallel the die rection-iiof movement ,of said slide; mechanism:

including a handle and a ratchet devicefor-rotating isaidjpinion; biasing means :urging said pinion outwardly relative to said frame; and movable means operatively connected to said frame and ,said pinion engageablewith said slideand operable by bodily movement of said pinion inwardly relative tojsaid frame toforce said slide outwardly relative to said frame; said pinion, during initial rotation being maintained outwardly relative to :said frame by 'saidbiasingmeans and moving'said slide outwardly relative to said frame until the reaction ofsaid slide-on said pinion exceeds the force of said biasing means, and further rotation of said pinion thereupon effecting bodily movement of said-pinion inwardly relative to said frame to :operate said movable means to force said slide outwardly relative-to saidframe. I

5. In a jack, in combination, a load bearing frame; a. force exerting slide reciprocablymolmt ed insaid frame for movement inwardly and outwardly relative to said frame, and having gear teeth extending therealong; a pinion engagedwith said-teeth andmounted in said frame for bodily movement in a direction parallel the direction of movement of said slide; mechanism including a handle and a ratchet'device for rotating said pinion; biasing means urging said pinion outwardly relative to said frame; 7 and movable means, including lever-means mounted on said frame andoperatively connected to said pinion, engageable with said slide and operableby bodily movement of said pinion inwardly relative to said frame, toforce said slide outwardly rela tive to said frame; said pinion,-during;initial rotation being maintained outwardly relative to said frame by said biasing .means and moving-said slide outwardly relative to said frame until the reaction of said'slide on saidpinion exceeds the force of said bias ngmeans, and further rotation of said pinion thereupon effecting bodily.

movement of said pinioninwardly relative to said framerto operate said movable means to force said slide outwardly relative tosaid frame;

6. In a jack, incombination, a load bearing frame; an elongated force exerting -slide-reciprocably mounted in said frame :for movement-inwardly'and'outwardly relative to said frame and having gear teethgextending along one elon ated surface thereof and inwardlyqfacing ratchet-teeth extending: along an opposite, longitudinal :surface thereof; a; pinion engaged with=said gear teeth and mountd said frame for bodily "movement 7 in adireotion parallel the direction of movement ofusaid slide; mechanism forrotating said pin-- ion; biasingcmeans ,urging said pinion outwardly relative to said .frame andmovablemeanssoperatively connected'to said frame :and said pinion, including a :pawl jenga'geable with saidaratchet teeth, operable by; bodilytmovement of saidpinion inwardly relative to said .frame :to :forcesaid slide outwardly relative to :said' frame; said pinion,

during initial rotation being maintained out:

wardly relative to said frame by saidbiasing means and moving saidslideoutwardly relative to said frame until the reaction :of said slidelon rocably mountedin saidframe fonmovementim wardly and outwardly relative, to said frame, and

having gear teethextending along one elongated surface thereof and; inwardl facing-ratchet teeth extending :along an opposite longitudinalsurface thereof; a ,pinion engaged with said gear teeth and mounted in said; frame for :bodily movement in a direction-parallel the direction of movement of said slide; mechanismffor-rotating said pinion biasing means urging said pinion outwardly relative to .said frame; movable means operatively connected to said frame and said pinion, including va-pawl ,eng.ageable' .WithLsaid ratchet teeth, operable by bodilymovement of said: pinion inwardly relative to said frame vto force said slide outwardly relative to said frame; said pinion, during initial. rotation being .maintained outwardly relative. to said frame -,.'by said biasing means and ;moving.said slide-1 outwardly relative to said frame a'mtil vthe reaction of ,said slide on said pinion-exceeds .the force ofWsaidbiasin means, and further rotation ofisaid Din'ionithereupon effecting bodily movement. ofsaid pinion inwardly relative to said frame ,to operate said movablelmeans toforce saidslide outwardly relative to said frame; and .releasableameans automaticallylrestraining retrogression of said slide inwardly relative to said frame while providing for movement of said slide and outwardly :relative to said frame; said.releasable:means, in moving to the slide release position operating said pawl to disengage, said ratchet teeth to release said slide for retrogression inwardlylgrelative to saidframe.

.3. -In a jack, inv combination, a load bearing frame; an elongated force exerting slide reciprocably mounted in :said .frame for movement inwardly, and outwardly relative :to said frame, and having gear teeth extending along one elongated surfacethereof andinwardly facingratchet teeth extending .along anuopposite lon itudinal surface thereof; a pinion engaged'with'said gear teeth and mounted in said. frame for .bodily movement in, a direcjti'on parallel the direction of movement of' said slide; mechanism for rotatinglsaid opinion; biasing means urging said pinion outwardly relativegto said fframe'rmovabletmeans operatively connected to said frame and said pinion, includingfa ,pawl engageable with said/ratchet "teeth, operable;by bodilymovement of said ,pinio'n inwardly relative to said frame, toforce said slideoutwardly, relative to said frame; saidlpi'nion, during initial rotation being maintained loutwardlysrelative' .to .Jsaid frame by said biasing means and movinglsaid slideoutwardly rela'tive'...t0, said frame until the reaction. of said slide-on said pinion exceeds :the force of said ibiasing means, ..and-,further rotation of V saidrpinion .-there,upon-.eifec.tingbodily movement of said pinion inwardly relative to said frame to operate said movable (means .'to force saidslide outwardly relative to, said frame; ro-

tatablelcam ,means automaticallyrestraining retrogression of said slide inwardly relative to said frame while. providing for movement of saidslide and-outwardly relative torsaid frame; ,an elerocably mounted in said frame for movement inwardly and outwardly relative to said frame, and having gear teeth extending along one elongated surface thereof and inwardly facing ratchet teeth extending along an opposite longitudinal surface thereof; a pinion engaged with said gear-teeth and mounted in said frame for bodily movement in a direction parallel the direction of movement of said slide; mechanism including a handle and a ratchet device for rotating said pinion; biasing means urging said pinion outwardly relative to said frame; movable means operatively connected to said frame and said pinion, including a pawl engageable with said ratchet teeth, operable by bodily movement of said pinion inwardly relative to said frame. to force said slide outwardly relative to said frame; said pinion, duringvinitial rotation being maintained outwardly relative to said frame by said biasing means and moving said slide outwardly relative to said frame until the reaction of said slide on said pinion exceeds the force of said biasing means, and further rotation of said pinion thereupon effecting bodily movement of said pinion inwardly relative to said frame to operate said movable means to force said slide outwardly relative to said frame; and means on said handle operable to release said ratchet device.

10. In a jack, in combination, a load bearing frame; an elongated force exerting slide reciprocably mounted in said frame for movement inwardly and outwardly relative to said frame, and having gear teeth extending along one elongated surface thereof and inwardly facing ratchet teeth extending along an opposite longitudinal surface thereof; a pinion engaged with said gear teeth and mounted in said frame for bodily movement in a direction parallel the direction of movement of said slide; mechanism including a handle and a ratchet device for rotating said pinion; biasing means urging said pinion outwardly relative to said frame; movable means operatively connected to said frame and said pinion, including a pawl engageable with said ratchet teeth, operable by bodily movement of said pinion inwardly relative to said frame to force said slide outwardly relative to said frame; said pinion, during initial rotation being maintained outwardly relative to said frame by said biasing means and moving said slide outwardly relative to said frame until the reaction of said slide on said pinion exceeds the force of said biasing means, and further rotation of said pinion thereupon effecting bodily movement of said pinion inwardly relative to said frame to operate said movable means to force said slide outwardly relative to said frame; clutch means connecting said ratchet device to said pinion; and means on said handle operable to release said clutch means to release said pinion for movement outwardly relative to said frame.

11. In a jack, in combination, a load bearing frame; an elongated force exerting slide reciprocably mounted in said frame for movement inwardly and outwardly relative to said frame, and having gear teeth extending along one elongated surface thereof and inwardly facing ratchet teeth extending along an opposite longitudinal surface thereof; a pinion engaged with said gear teeth and mounted in said frame for bodily movement in 'a direction parallel the direction of movement of said slide; mechanism including a handle and a ratchet device for rotating said pinion; biasing means urging said pinion outwardly relative to said frame; movable means operatively connected to said frame and said pinion, including a pawl engageable with said I biasing means and moving said slide outwardly relative to said frame until the reaction of said slide on said pinion exceeds the force of said biasing means, and further rotation of saidpinion thereupon effecting bodily movement of said pinion inwardly relative to said frame to operate said movable means to force said slide outwardly relative to said frame; means on said handle operable to release said ratchet device;,clutch means connecting said ratchet deviceto said pinion; and means on said handle operable to release said clutch means to release said pinion for movement outwardly relative'to said frame.

12. A jack comprising, in combination, a load bearing frame; an elongated force exertingslide reciprocably mounted in said frame for movement inwardly and outwardly relative to said frame, and having gear ,teeth extending along one elongated surface thereof and inwardly facing ratchet teeth extending along an opposite longitudinal surface thereof; a pinion engaged with said gear teeth and mounted in said frame for bodily movement in a direction parallel the direction of movement of said slide; mechanism for rotating said pinion; spring means urging said pinion outwardly relative to said frame; a lever pivoted adjacent one end to said frame; a pawl connected to the short arm of the lever and extending toward said ratchet teeth; and link means connecting the long arm of the lever to said pinion; said pinion, when first rotated, being maintained outwardly relative to said frame by said spring means and. drawing said slide outwardly relative to said frame until the reaction of said slide on said pinion exceeds the force of said spring means, said pinion thereupon rotating inwardly along said gear teeth to swing said lever to move said pawl to force said slide outwardly relative to said frame.

13. In a jack, in combination, a base; a force exerting member reciprocably mounted on said base for movement inwardly and outwardly relative to said base; an operating element for said member engaged therewith and movable, relative to said base and said member, in a direction substantially parallel to the direction of movement of said member; biasing means urging said element outwardly relative to said base; whereby, as said element is operated, it will move said member outwardly relative to said base until the reaction of said member on said element exceeds the force of said biasing means; further operation of said element thereupon effecting inward movement of said element relative to said base; and means operatively associated with said member, said base and said element and operable by said element, during such relative inward movement of said element, to force said member outwardly relative to said base.

14. In a jack, in combination, a load bearing frame; a force exerting slide reciprocably mounted in said frame for movement inwardly and outwardly relative to said frame and having gear teeth extending therealong; a pinion engaged with said teeth and mounted in said frame for bodily movement in a direction parallel to the direction of movement of said slide; mechanism for rotating said pinion; biasing means urging said pinion outwardly relative to said amass base; and .movable means engageable with said slide. and'opera'tively associated with said. frame a andcsaidpinionsaid movable'meansbeing operable ,by ibodily inward movement .:of ;said pinion, .relativejto said'base, .to force said slide outwardly relative jto said base; "said pinion, during initial rotation being maintained {outwardly rela'tive to said ,base'by said biasing means and movingrsaid slide outwardly relative to said base until-the reaction of said slide on saidpinion exceeds the lforceiof said 'bias'ingmeanfi, and further rotatidn'eof said pinion thereupon effecting bodily movement; of said pinion toward-said base to operate said movable means to force said "slide outwardly. relative jto 'said base.

'15.,In a jack, in combination, 'a base; a force exerting member reciprocably mounted on -said base for movement "inwardly and butwardly -relative to'saidba'se; an operating element for said ,member engaged "therewith and movable, rela- I 'tiveto saidbase and said :member, in 'a direction substantially parallel to the direction of move- 1 ment of said member; fbiasing means urging said elementoutwardly relative tosaid base; a lever :pivoted on; said base .and having a flongfatm 1 eonn ecteld to said 1qpfir-ating element to swing said-lever "asisaid element gmov s i elativeito I said base; and cooperating 'paw'r and ratchet means 'on theshort' arm of saidlever and-on said memiber to" force said member outwardly when said lever is swung by li'IWaIQ mOVGMCIlt ofsaid elemen't; whereby, as said element is'operated, it

will movesaid'member'outwardly relative to said base until the reaction of said-member on said element exceeds the =force of said biasing means; 'further'operation of said element thereupon effe'cting' inward movement or said element-relative to said base to swing said {lever to operate said pawl and ratchet means to force said slide outwardlyrelative' to said base.

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