USRE14235E - A coepokation of - Google Patents

Description

E ma I Qd d w M u wlTNEsysEs l. E. H INDMAN. UFTING JACK. -APPLlcAT1oN mio My 24n91e.

2 SHEETS- sneu 2.

misma 1360.26, 1916.

Md@ M 'Wm u WITNESSES UNITE STATES PATENT OFFICE.

TSAIA'H E. HINDMAN, 0F GRAFTON, PENNSYLVANIA, ASSIGNOR TO THE DUFF MANU- FAOTUEIN'G COL'PANY, OF PITTSBURGH, PENNSYILANIA, A CORPORATION 0F LIFTING-JACK.

Specification of Reissued Letters Patent. Reissued Dec, 26, 1916.

@riginal No. 1,652,921, dated February 11, 1913, Serial No. 719,018, filed September 6, 1912. Application for reissue filed May 24, 1916. Serial No. 99,704.

f 2 is a sectional view on the line II-II 4of Fig. 1, 8 is a detail view of portions of the clutch mechanism on a larger scale, and in which the angle of the wall of the slot which fornisthe cam has been exaggerated.

My invention has relation to lifting jacks, and iS/more particularly applicable to jacks `in which it is desired to rapidly lower the jack under the weight of the load.

The invention is designed to provide a simple and efficient clutch mechanism by the action of which the load can readily be lowered without shifting or adjusting any Aof the various parts.

The precise nature of my invention will l l be best understood by reference to the accompanying drawings, which will now be described, it being premised, however, that various changes may be made in the details of construction and general arrangement of the parts, without departing from the spirit and scope of my invention as defined in the appended claims.

In the accompanying drawings, have shown the invention .as-applied to a high speed screw jack, in which the numeral 2 designates the base of the jack having an upwardly projecting cylinder 3 provided with a head @having a central'nut 5. The quick pitch screw stemV 6 extends down through the nut and has secured to its lower end a head 7 which is adapted to limit the upward movement of the screw 6. Surrounding the cylinder 3 is a lifting shell 10,

lwhich carries at its top a lifting plate 12.

Extending through a bearing 18 in 'the side ofthe shell is an operating stub shaft 14 having a squared outer end 15 and carrying within the shell a bevel gear 16 intermeshing with a horizontal bevel gear-17, which is keyed to the thread shaft 6. Surrounding the shaft 6 Yabove the bevelV gear 1 7 is a steel ring and ball race 18, whichis also secured to the shaft 6 to rotate therewith. The upper face of the ring 18 is provided with an annular groove to 'receive a row of balls 19, which are also seated in an annular groove in the upper ball bearing plate 20, which is centered on the reduced portion 21 of the elevating screw 6.

Rotatably mounted on the upper face of the bevel gear 17 and surrounding the steel ring 18, is a worm wheel 22, which engages the threads of a worm 23 keyed to a shaft 24, which is journaled in bearings 25 formed.

in a lateral extension on the shell 10. The' inner periphery of the worm wheel 22 is provided with a plurality of cam-shaped grooves or recess 26, in which are seated rollers 27, which engage the eccentric cam I faces 26L and the periphery of the ring 18. The cam faces 26 are'eccentric to the periphery of the ring 18, aswell as the line 26b which is concentric to the periphery of the ring 18, as clearly shown on Fig. 3 in which vthe angle of the cam face 26 .has been slightly exaggerated.

28 designates springs, which are seated in recesses adjacent to the cam recesses 26, and are arranged to engage the wall of said recesses and their respective rollers to hold the rollers toward the narrow portion of the cam recesses 25, so as to lock the worm wheel 22 with the ring 18 when the worm wheel'is moved in one direction.

Secured to one of the ends of the shaft 24 is a crank 29 adapted to rotate the shaft 24 and worm 23 when the screw lowered.

The operation of the device is as follows The jack is placed under'the load and the screw is elevated by means of the bevel gears 16 and 17 in the usual manner, without rotating theV worm 22. The frictional engagement of the rollers 27 between the cam surfaces 26 and the ring 18 will prefrom the provision of :t worm and 'worm wheel connection for lowering the load of a screw jack, in which the downward movement of the screw is prevented by a, worin and Worm wheel.

A furtherr advantage results from the provision of an automatic clutch which will permit the screw to be rotated to elevate the jack-without rotating the worm wheel and nection with said screw, and an automatic clutcli connection between the worm Wheel and the screw for preventing the rotation of the 'screw in lone direction relative to the worm wheel but which' will permit free movement of the screw relative to the Worin wheel in the other direction; substantially :is described.

` 3. A lifting jack having ,en elevating screw, gearingy for rotating the screw to ele'- vate it7 e worm wheel, tfclutch connection between said worin wheel and the screw erranged to prevent the' Screw from 'rotating relative to the worm Wheel under the action of the load, e worin engaging said Worm wheel and normally preventing rotation thereof, and Ineens for actuating seid worin to rotztte the worm wheel; substantially as described.

4. A lifting jack having a lifting screw, two independent sets of mechanisms con nected to the screw, one of said sets of mechlatnisins including en automatic clutch to pre- 'vent the Screw from rotating in one direction and to permit freerotetion of the screw in the other direction by the other mechenism; substantially as described.

5. A lifting jack lia-ving en elevating screw, Ineens for rotating seid Screwto elevate'it e rotatable, but normally stationery clutch connected to -said screw and arranged to permit the screw to rotate in a direction to elevate it but to prevent it from rotating in the opposite direction, and means to rotote seid clutch to permit the screw to rotate ity in said opposite direction 4to lower it lower; Vsubstantially es described.

ln testimony whereof, I have hereunto set my hand this 22nd clay of Mey, 19l6 SAIAH E. HNDMAN. lWitnesses:

Gro. B. BLEMING,

AMY REYNOLDS.

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