US1658586A - Lifting jack - Google Patents

Description

Fe. 7, 192s.

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T. H. WITTLIFF LIFTING JJACK Filed June 23. 1923 3 Sheets-Sheet 2 INVENTOR.

ATTORNEYS Feb. 7, 1928.

T. H. wlTTLlFF LIFTING JACK 3 Sheets-Shea?I 5 Filed June 23. 1923 f A TTORNE I of the extension handle to holdlsaid :rod

in sliding relation thereto. Between i the" parallel plates 25 of the operating handle the retaining pawl `34- `and they actuating pawl 35 are mounted upon the pivot pins Yl2 and :26, respectively. Each of said pawls is provided at one side with a circular bossA 36, 37, respectively, about .which coil springs 38, 39, respectively, are swung, the-ends of said springs being securedto the adjacent side of the handle and to the body portions of said respective pawl,`saidfsprinvs thus serving to hold the free ends of said pawls i in resilient contact with the rack on the lifting bar. Such pawls areeach provided with a plurality of teeth at their router ends, said teeth being spaced the proper distance to engage with correspondingly spaced teeth `ot' the rack. This provides a broaderiarea of contact between the pawls and the rack and prevents damage to one-tooth renderingthe device inoperative.V i

The mechanism thus tar described is suficient to carry out the operation of `elevating the lifting bar, .the springs` on the respective pawls holding` the same insliding engagement with the cap and the upper ends of said pawls engagingsaid rack teeth alternately as the operating handle is moved up and down. l l i The mechanism for reversing the action of the pawls and holding the retaining pawl away from the rack bar during a portion of the period of engagement of the actuating pawl with the rack bar when the lifting bar is lowered now will ,be described. This mechanism is best shown in Fig. 2 and comprises a spring supporting plate 4.1 having a rearwardly projecting stud 42 secured centrally thereof. Said stud extends through an aperture in the pawl 34 adjacentto and transversely of the pivot pin '22. SaidA stud projects rearwardly a short distance beyond the rearward face of said pawl and is provided with a depending pin 43 secured to said rearward end. A coil spring 44` is mountedupon said stud between the depending `pin and the rearward tace of the pawl 34 and has one endv engaged in the body of said pawl and the other end hooked4 over said depending pin.l Through the action of this spring the depending pin is normally held in a vertical position, its intermediate portion resting against a shoulder. 45 formed on the rearward faceof said pawl34.

The forward face of the spring supporting plate is provided with enlargements 46, 47,

the respective ends of which are suitablyrecessed to receive the ends of the pawl controlling springs 48, 49, respectively.

As is Vmore particularly shown in Figs. 4,-

the two halves of which are olf-set in opposite directions from a median line so as to 've the ends of said respective springs reedom of motion past the side edges of Athe ends of the plate opposite from the -point of'attachment. The outer ends of the controlling springs are each bent downwardly and `outwardly to form the pawl contacting terminals 51, 52, ot said respective springs. As is clearly shown in Fig. 6, the actuating pawl 35 is provided on its rearward face with the upper and lower cam extensions 53, 54. Adjacent the cam extension 53 a depressed or cut away portion` 55 is provided against which the contact terminal51 of the spring 48 rides when the spring supporting plate is in alignment with the axes of the operating pawls. Adjacent the camextension 54 the pawl 35 is cut away to provide space for the free movement of` the contact terminal 52 when the spring supn porting plate is in its cent-ral position.

It will be noted from the several iigures of the drawing that when the sliding rod 2f] is in retracted position, the spring supporting plate occupies its normal position in alignment withthe central axes ot the pawls and that when saidv rod is moved forward the beveled terminal at its inner end will engage the depending pin V43and move the same away from' the shoulder 45 on the rearward face of the retaining pawl. The lower end of the retaining pawl is suitably slotted to receive'the end of the rod when it isprojected to its full forward position.

VlVhen the rod is so projected and the pin 43 is turned, it will rotate the stud, together with thesupporting plate 41 secured thereto. Such rotation of the plate will tend to swing the endsoic the controlling springs to a position in alignn'ient with the cam extensions 53 and 54 of the operating pawl 35. springs may` not immediatelymove to said position if their contact terminals 51" and 52 are disposed wit-hin the recessed or cui. away portions ofthe pawl at the time when the slide rod is shifted. However, upon the actuation of the operating lever and the rocking;r of the pawls upon their pivots, said terminals .will be carried beyond the ends of said cam faces during a portion of such rocking motions of the pawls and will then automatically swing to a position in which their contact terminals 51. 52, are located in alignment with the respective cam extensions and 54.

The operation of raising the actuating or lifting bar of the jack, `as has already been indicated, takes place when the spring sup porting plate occupies a position in alignment with the median line of the pawls. The operation of lowering the lifting har Occurs when the spring sul'iporing plat:`

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is rotated about its supporting stud and the controlling springs are placed in cam contacting position. lrVhen so adjusted, the action ot' the pawls is reversed.` Thus, when the outer end of the extension handle is low ered, the contact terminal 52 rides against the cam` extension 54 on the pawl 35 and holds its top engaging end free. of the rack for a distance of one rack tooth. As it clears said tooth, the contact terminal 51 engages the cam extension 53 and forces the engaging end of the pawl 35 interengagement with the rack. The operatinghandle isthen in a substantially horizontal position. Upon further depressing the outer end ol the operating handler, the cont-act terminal 51 rides over the cain extension 53 and places tension upon the springv t8 so thatit tends to throw the retaining pawl 34: in a rearward direct-ion. The pawl 341 will not move tree of the rack teeth until 'the lifting bar has been slightly elevated to relieve its forward end from the weight 'of the load. Vhen the pawl is so relievedv it will move rearwardly out of engagement with the rack teeth and will be held clear of the rack until the operating handle has assumed an approximately1 horizontal yposition in its return, while its outer end `is being moved back to an extreme upward position. During this last half of the upward movement `of the outer end of the operating handle the upper end of the retaining pawl 341; will be restored to rack engaging position and as the outer end of the handle approaches its upper limit of motion, the Contact terminal 52 ot the controlling spring 49 will be brought against theLcam extension 54 ot the actuating pawl and move the same outwardly as soonasthe upper end ot said pawl is relieved of the weight ot the load through the engagement of the up-` per end of the retaining pawl therewith.

In the modified forni of Construction illustrated in Figs. 9 to l2, inclu-sive, the body of the jack and the lifting bar and the pawls and the pivoted spring supporting plate are identical with the structure heretofore described. In place, however, oit using a slid ing Arod having a beveled cam surface at its forward end tor rotating the spring supporting plate, aportion ot the handle is arranged to be bodily shittable to serve this Yfunction. Thus the forward section ot' the handle 6l i-s pivoted upon the pin 22 and a slidable section of the handle 62 is telescopically engaged within said pivoted section of the handle. Said sliding section is provided at its forward end with an extension 63 having a beveled face 6l for engagement with the depending pin 43 attached to the rearwardly projecting st-ud 42 upon which is secured the spring supporting plate 41. Said beveled face acts in exactly the same manner as the beveled tace on the sliding rod and when said portion `ofthe handle is retracted it permits the pawls to act normally in causing the jack to raise the load, while when said section of the handle is projected said beveled 'tace swings the spring supporting block to bring the springs carried thereby into a central position whereby the action ot' the pawls may be reversed and the j ack caused to lower the load. In order to retain the sliding `section ot the handle in either ot' its adjusted positions a spring detent 65 is provided. ,Said detent com prises a section of wire bent in the torni of an elongated rectangle, as is clearlv shown in Fig. 12, and having a notched tubular spacing member 66 at its 'forward portion. The rearward portion ot said loop comprises the terminal ends oi the wire 67 which are adapted to he engaged intorecesses 68 'lorined in the pivoted section 6l ot the handle. When so engaged the tubular spacing member 66 is adapted to engaged a notch 69 formed in the rearward portion ot' the pivoted section ot1` the handle and the sides of said detent member are adapted to engage beneath a pair of lateral ears .71 formed upon said pivoted section o'l' the handle. The upper edge of the sliding` section ot the handle is provided with a recessed portion 7 2 provided with two spaced seats 73, 74, of a size suitable to receive said tubular spacing member 66. When said.` member is engaged in the seat Tft the sliding section of the handle will be in its rearward position and the jack will Lbe adapted 'tor elevating the load. lWhen the sliding section of the `handle is shifted torwardly and the member engaged in -the seat 78. the mechanism of the jack will be adapted for lowering the load.Y It will be noted that `the seats 73 and 7d are spaced from each other and that when the detent is engaged y in either ot said seats there is no tension upon the handle, inasmuch as when the seat 73 is engaged by the detent the depending pin t3 has passed over the beveled tace and is resting against the 'flat side of the torward extension of the handle.

In order to facilitate the manipulation ot the jack trom a position beyond the body olf an automobile or under similar conditions, an extension handle may be provided. As is clearly shown in Figs. 9 and 10," said f extension handle 75 may be provided at its rearward end with a hand grip 76 formed by turning the rearward end of the bar `of said extension at right angles to the main body portion thereof. The forward section of said extension is provided with an oblique slot 77 and a notched forward end 78. The lower portion of said handle adjacent the notch is extended to form a projecting tongue 79 for a purpose to, be hereinafter explained. The sliding section ot the handle is provided with two laterally project the extension handle when the ze ing studs 81 and 82, the stud8l being located at the rearward end ofsaid sliding section and being adapted to he engaged through the slot of the handle extension.

`A wing nut 83 is screW-threadedly engaged upon the stud 81` and permits the handle extension to be rigidly secured to the slid ing section of the handle. It will be obvious that by releasing the tension upon the Wingnut the extension of the handle may be moved rearwardly with respect to the sliding section thereof a distance suicient kto permit the disengagement of the notch from the stud 82. This will permit the `handle to be folded when the sliding section of the handle is detached from the jack.` In folding the extension upon the sliding part of the handle the small semicircularnotch 8O in the upper edge ofthe extension permits said two handle sections to be broughtkinto parallelrelation. The projecting tongue 7 9 act-sas a stop to assist in engaging the stud V82 with` the notch in parts are restored to opera-tive position.

Other modes of applying the principle ot my invention may be employed instead of the one explained, change being` made as regards the mechanismpherein disclosed, provided the means stated by any of the following claims or the' equivalent of such stated means be employed.

I therefore particularly point out and dis` tinctly claim as my invention z- 1. A lifting jack comprising incombinas tion a standard,` a lifting bar slidably mounted in said standard, a .rack formed onV one side of said lifting bar,- a pairof operating pawls disposed onebehind the other adja cent to and 1n Contact with said rack, a rotatable spring4 block mounted upon one ofV said pawls, a. pair of oppositely directed ccny trolling springs mounted upon said spring block, and means for rotating said spring block together with said springs to move the latter into,l and out of controlling position with respect to said pawls. i

2. A lifting jack comprising in combination a standard, a lifting bar slidably mounted in said standard, a. rack `formed on one side ofsaid lifting bar, an operating handle pivotally supported upon said standard, an actuating pawl carried at the forward end oi said operating handle, a plurality of cam faces upon said actuating pawl', a retainingpawl mounted upon said standard, pawl con` trolling means mounted uponsaid retaining pawl, andmeans associated `With said handle' for shifting the position of said controlling means.

3f A lifting jack comprising in combination a standard, a lifting bar slidably mounted in said standard, a rack formed on one side of said lifting bar, an operating handle pivotally supported upon said standard, au actuating pawl carried at the forward ond of said operatingl handle, a plurality ot cani, faces upon said actuating pawl, a retaining pawl mounted upon saidstaiulard, paul controlling mcans pivctally mounted upnusaid retaining pawl, means carried by said con trolling means for contacting with said, cani .surfaces on the actuating paul. and means` associated with saidppcrating handle fon shifting the position oi said paul controlling means. l y, y

4. A lifting-jack comprising in combina# tion a standard, a lifting bar slidably mount`- ed in saidstandard, a rack formed on one side of said lifting bar; a pair of operating pawls disposed one behindthe other adju-` cent to and in contact with said rack, means` for controlling said operating pawls mounted upon one of said pawls, an operating handlchaving apivoted and a slidahle section, a. beveled extension upon said slidable tion of the handle for shitting the position of said controlling means, a spring detent on said pivoted section of said handle. and a pair of spaced seats engaged by said datent for holding said sliding section `otsaid han dle at load-elevating or load-lowering adjustment, respectively.

5. An operating handle for alitting jack comprising in combination a section .pir/'etall ly secured to the main body of the jack, a single'sliding section engaged Withirrand reciprocable with respect to said pivoted scction,` an extension section pivotedy to said" sliding section, and means toifirnily loclcsaid extension section with said sliding section to .hold said extension at an up ard angle to said sliding section and to permit thefold#` lng of said extension section in parallel rela`` tion with said sliding section.

frnnononn n. Wirrnnua i i `10.*) Signedby me, thisV 20th dav of lunalfllr

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