US1396951A - Lifting-jack - Google Patents

Description

W. H. FOWKES.

LIFTING JACK. 4unicnlon msn mn. s. |919.

1,396,951 Patented Nov. 15, 1921` ,7 2 sains-'suur 1; 5 66;/

'if i v I /5 w. H. FowKEs.

LIFTING JACK.

APPLICATION FILED MAR. 8, 19,19.

2 SHEETS-S Patented N0v. 15, 1921.

MEET 2.

UNITED STATESA PATENT OFFICE.

WILLIAM HERBERT rowxnsfor CHICAGO, ILLINOIS, AssIGNon r.ro BUDA` ooMrANY,

`A coRPoRA'rIoN or ILLINoIs.

. My invention relates to those liftingiiaclrsf usually designatedin the trade` as ball'bean ing screw-jacks, and has for `its chief aim in general to improvethe construction and increase the efficiency and utility of jacks of this type, and in particular to produce a quick-raising self-lowering j ack,` the selflowering action of which is automatic. i

` One of the salient objects kof theinvention is to produce `an automatic self-lowering jack capable of being ratcheted down should the jack stick when in load sustaininglposition; another object is the provision in a jack of a centrifugal frictional controlcontion and therebypermit the jack to auto-I` structed and arranged to automatically govern or uniformlyretard the descent of the jack under differing load conditions by virtue ofthe variable centrifugal braking action setup in said control rendering it adaptive to whatever loadis imposed upon it;

" a further object of mylinvention relatesto the provision of; driving `mechanism comprising leverage Increasing gearing` arranged intermediate the operatingstub shaft of the ]ack and such control, whereby the rotative speed of :the moving `partsof said control is materially increasedover that of y saidshaft and :to therebyobtain a corre` spending leverage increment of `braking power at said shaft; a further object ofthe inventionis to intermediately `provide said drivingr mechanismwithi` a positive acting` brake normally set tohold thejaclr against involuntary descent `under load, said. brake being'manually releasable to instantly bring1 matically descenduunder full `control independently of said brake; and afurtherobject of the invention `is to` so organize'the automatic control and the cooperating gearing with itspositive brakeso that theseparts together withthedetachable casing that carries themlconstitute a self-contained mechanism, readily detachable without disturbance of the partsfromthe supporting sleeve of the jack and asreadilyattachable.

`Speciiicafionof Letters Patent.

Patented Nov.15,192`1.

Application `iled March 8, 1919.` Serial No. 281,388.

These, together with such other advan tages as may be hereinafter described, or

`are incident to my invention, I attain by means of a construction illustrated in preferred form in the accompanying drawings. wherein: y i .Figure 1 represents a vertical sectional view of a jack to which my invention is shown applied; y

Fig. 2 is a View taken along the line 2--2 of Fig. 1 looking in the direction of the arrows, the lower partbeing in side eleva tionand the upper in partial cross-section;

Fig. 3 is a sectional view taken from the interior of the gear casing along the line 3-3 of Fig. 1; and i Fig. 4 is a fragmentary View of a slightly modified .form of `the control illustrated more particularly in Figs. 1 and 3. Y

Referring to the drawings, the reference character` 5 denotes the standard of the jack, and 6 designates the lifting sleeve movable' thereon and having as parts thereof the head cap 7 and the gear plate or case 8. lVithin the upper end of the standardis mounted the usual operating nut 9 carrying the lift'- ing screw 10 which is preferably pitched for a quick action lift. Keyed to the upper re-` duced end of the screw 10 is a bevel gear 11 having a meshed engagement with a bevel pinion 12 `whose operating shaft 13 is journaled in an extended bearing 14 formed in the casing 8 and which vis terminally provided; with any suitable operating mecha# nism, the `inner ratchet ortion only of which is indicated at 15.` lVithin the head of the sleeve and between the opposed faces of the capand bevel gearl is a pair of superimposed bearing plates 16 and 17 provided intermediately with a series ofant-friction members 18. The base of the j ack is desig nated by the reference character 19.

Before passing to a specific description of the preferred component elements of the principal mechanisms involved in the invention, the following brief Y localization of these mechanisms may be of assistance in` clarifying such description. letter A indicates a ratchetmechanism about shaft 13 which idles during `the lifting action of the jaclr. but is brought into operation upon any reverse rotation of said brake B. `Upon release ofthe brake the soV The reference centrifugal control C, or C as modified in Fig. 4, comes into action to automatically govern the'descent of the jack under its load, and thereby prevents any disability occurring to the jack which would be the case were its descent not retarded.

These, mechanisms are all associated and coperative, andas a whole constitute a complete geared device devoid of any need for manual adjustment to govern the selfloweringof the jack, the Agearing being such as to multiply the leverage at mechanism C so that the increment of such leverage is applied through mechanisms B and A to shaft 13 ina simple but very effective manner.

Similar characters designate like parts of these mechanisms throughout the several figures of the drawings.

The ratchet mechanism A consists of a ratchet 2O secured to the shaft 13 to rotate with itiand a loose spur gea-r 21 providedwith spring pressed pawls 22 designed to ratchet idly over' the'teeth of the ratchet during the actuation ofthe shaft by the operating mechanism tolift the jack, and to engage them to impart motion to said gear 21 upon reverse rotation'of the shaft under the influence oa load unless positively checked by the brake B. The ,i latter comprises a largefspur gear 23 marginally flanged at one side to forman annular friction band 24 and integrally provided on .the other side Y With a' small lpinion 25 iii-mesh with the large spur gear 21, saidgear 23 and pinion 25 being-loosely mounted for rotation about a stub shaft126 Whose outer end 26 is threaded into an enlarged portion 8 of the casingSfgWithin this band are apair of cams 27 and`28, the former axially mounted on a pins29 threaded the casing 8, and being provided'vvith an arm 27 connected tothe cam28 at'a point removed from its axis by-a link member 30, which latter has a tension springconnection 31 with the cam 28 lnormallyv acting to maintain the camming facesv incontact with the inner surface of the Aband at opposed points thereof.

' The cam28 is secured to the inner end of a fulcrum shaft 32 which is journaled in said enlargementS and is extended therethrough to rigidly ca rry at its outer end a lever 33 having aterminal finger piece 34 intermediate the guards 35 and 3G formed on the casing 8, the guard 36 also constituting a fingerV piece when it is desired to manually dpress -th'elever iinger piece 34 to- Ward it and thereby release the brake so l lthat-the automatic control C may function.

This control C contemplates the provision of an annular friction band 37 secured to an inner wall portion 6 of theV sleeve lin any suitable manner concentric with the shaft 38, the latter'having its outer end fixed in a vhub portion 8a of the 'gear case and loosely carrying a sleeve 39 which is formed with a Lof the disk are Weighted liber brake shoes -l-.l

the weighted portions of which are lndir cated at 42. These shoes may he held in position against the inner face of the band by the light helical springs 43 which extend between the lever arms 44 of the shoes and eyes 45 provided on a small disk 46 secured to the sleeve. The tension of the spring preferably of a quality permitting the ratcheting down of the jack by the shaft operating mechanism 15 should the jack stick under load, and to permit the leverage increasing gearing to gain a prompt start upon release of the brake B. Instead of the springs 43, pins 43 may be advantageously employed to approximately position the shoes, as indicated in Fig. 4 which illustrates a modified form of weighted lever brake shoe embodying the short arm shoe 41', and the long lever arm 44 which is provided with the'vveight 42. The pin 43 is so positioned that with the control at rest a slight clearance normally exists between the shoe and the band.

Obviously, the disk 40 of the control is the high speed member of the mechanisms above described, and the centrifugal force present during disk rotation tends to throw the weighted brake shoes outwardly against the brake band 37, to frictionally retard the descent of the jack sleeve, the frictional braking effect correspondingly increasing to ,counteract any increase in the rate of disk load conditions and thereby automaticalli7 check such increase of speed. Stated di ilerently, the centrifugal braking action of the control accommodates itself to variable loads which may be sustained by the jack and. provides for a substantially normal rate of selfloivering descent within the capacity limit of the jack. Furthermore, it will be upparent that the leverage increase obtained through the gearing multiplies the braking eflect'of the control to gain an increment of braking power at the operating shaft 13, the lower speed member of the mechanisms. From the foregoing, it will be seen that in the liftingv action of the jack these stated mechanisms are at rest, the positive brake serving to prevent anyinvoluntary descent ofthe jack, release of which brake by depressing iinger piece 34 initiates the selflowering movement of the ack. This movement, as already set forth, is then wholly governed by the automatic control, such control being characterized by an entire ab- `these mechanisms proper, and their relation to gear case 8,1are along simple and efficient lines, and as a whole the device takes upon itself a very compact form inviting ease and economy in manufacture and the parts are readily assembled and applied to the jack. With the single exception of theV band 37, all the parts may be brought together as a self-contained unit carried by the casing 8, uncoupling of which permits the removal of the unit. Other advantages will readily appear to those skilled in the art.

I do not desire to be understood as limiting myself to the precise details `of construction, or to the exact arrangement of the various parts or elements as shown` as it is manifest that variations and modi ications thereof may be made without depart ing in any way from the spirit and scope of my invention and improvements, the instant embodiment of which is` illustrated in a preferred form. I therefore reserve the right to all such variations and modifications as properly fall within the scope of my in vention and ,the terms of the following claims.

I claim: y

1. In a self-lowering lifting ack, the combination of af stationary mem er, a lifting member movable thereon, a revoluble actuating member therefor, a ratchet mechanism associated with said actuating member, a locking mechanism comprising a plurality of oscillatory cams for 4releasably holding said liftin member against involuntary a descent under load, an automatic controlling mechanism having a movable part thereof `constructed andarranged with reference to a fixed part thereof whereby to centrifugally retard the descent of said lifting member upon release parts being disposed about a fixed axis of support on the movable member,

and said mechanisms associated in train by gearing designed to drive said movable part at a higher rate of speed than that of the revoluble actuating member.

2. In combinatioma casing, an actuating shaft therein having a ratchet mechanism including a loosely mounted .gear wheel, a pinion in mesh therewith provided with a 'spur gear having an annular band, a plurality of lookin cams carried by said easing and normally ilicking with said spur gear band, a shaft mounted in said casing and provided with a sleeve having a pinion meshed with said spur gear, a fixed brake band concentric by said sleeve and pivotally provided near its margin with a plurality of lever brake of said locking mechanism, said withsaid shaft, a rotary disk carried shoes designed to flexibly engage said fixed l brake ban as the disk rotates, said locking cams being provided with a manually operated lever extending through said casing.

3. In a jack, the combination of a support, an actuating shaft therein having a ratchet mechanism including a loosely mounted gear wheel, a pinion in mesh with said wheel, a spur gear connected to said pinion and provided with an annular band, a plurality of locking cams arranged within said banc, a spring for normally urging said cams into locking relation with said band, manual means for releasing said cams against the force of said spring, a sleeve mounted in said support and provided with a pinion meshing with said spur gear, a stationary brake band concentric with said sleeve, a disk carried by the sleeve, a plurality of brake shoes mounted on said disk and adapted to engage said band, centrifugally `actuated means for forcing said brake shoes into engagement with said band, and a lifting member connected with said shaft. i

4. In a lifting jack, the combination of a casing, a lifting member movable therein, a rotatable shaft for actuating said member, ratchet mechanism connected with said shaft, locking mechanism for preventing reverse rotation of said shaft, comprising a pair of locking cams mounted in said casing, an annular rotatable band surrounding said cams and operatively connected with said shaft, means for normally urging said cams into locking relation with said band, manual means for releasing said cams, and a controlmechanism comprising a rotatable disk connected to and adapted to be actuated bv rotation of said band, a. plurality of contri ugally-actuated brake shoes carried by said disk, and a stationary drum surrounding said brake shoes and adapted to be engaged thereby.

5. In a lifting jack, the combination of a i casing, a lifting member mounted therein, a shaft for actuating said member, a gear wheel surrounding said shaft, pawl and ratchet connections between said wheel and said shaft., an annular drum adapted to be rotated by said gear wheel, a plurality of cams mounted within said drum, means for normally urging said cams into locking relation with the drum, manual means for releasing said cams, a disk connected to and adaptedto be rotated by said. drum, a plurality of centrifugally actuated brake shoes carried by said disk, and a stationarily mounted iannular drum surrounding said shoes and adapted to be engaged thereby for controlling the speed of rotation of said

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