US361944A - Lifting-jack - Google Patents

Description

(No Model.) 2 Sheets--Sheet l. Y

J. W. HAWKINS.

- LIFTING JACK. 7 No. 361,944. Patented Apr. 26, 1887.

. mm mm (No Model.) 2 Sheets- 8mm; 2.

J; W. HAWKINS.

LIFTING JACK.

No. 361,944. Patented Apr. 26, 1887.

v lifting-pawls.

UNITED STATES PATENT OFFICE.

J. IVESLEY HAWKINS, OF KENT, OHIO.

LlFTlNG-JACK.

SPECIFICATION forming part of Letters Patent No. 361.944, dated April 26, 1887.

Application filed February 2, 1887. Serial No. 226,262. (No model.)

To all whom it may concern;-

Be it known that I, J. WEsLEY HAWKINS, of Kent, in the county of Portage and State of Ohio, have invented certain new and useful Improvements in Lifting-Jacks; and Ido hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it pertains to make and use the same.

My invention relates to improvements in lifting-jacks; and it consists in certain features of construction and in combination of parts, hereinafter described, and pointed out in the claims.

This invention is designed as an improvement on a lifting-jack patented June 8, 1886, to J. Wesley Hawkins, No. 343,312.

In the accompanying drawings, Figures 1 and 2 are respectively a side and front eleva tion of a lifting-jack embodying my invention. Fig. 3 is an elevation in section, and Fig. 4 a plan of the retaining-pawls and connected mechanism. Figs. 5 and 6 are respectively a side and end elevation of the yoke for the Figs. 7 and 8 are plans, respectively, of the lifting and releasing levers.

A represents the standard, that is usually of cast-iron, with a broad base, A. The lower or main portion of the standard has avertical recess, A, in which operates the lifting-bar B. This bar has a head, I), for lifting weights that are sufficiently elevated, and a toe, b, that extends outside of the recess A, for lifting loads that are lower down-such, for instance, as rails of a railroad-track-by reason of which this device is well adapted for a track-jack. The bar B slides through sleeves a and a, connected with the standard, these sleeves forming guides for the lifting-bar. A forked lifting-lever, C, is pivoted at c to the standard. The outer end, 0, of the lever has a conical socket for receiving a wooden extension-lever. (Not shown.) To the extreme ends of the prongs c are pivoted hooks D, the latter engaging bails E of the yoke E. This yoke is rectangular in plan, with the end pieces, 6,

rounded to form fulcrums for the pawls F.

These pawls engage, respectively, gibs G, that clamp the lifting-bar. Each gib has lugs g located below theyoke, which prevent the gibs from being lifted out of place.

Each gib on the back side has a tooth similar to the tooth g of gibs J, that engages a corresponding notch, f, in the engaging pawl and retains the gib and pawl in the proper relative posit-ion, causing them to move together. The face f of each pawl is slightly eccentric with the axis of the pawl, by reason of which, when the yoke is elevated by the hoisting-lever, the gravity of the gibs and pawls causing them to descend, the gibs are made to clamp the liftingbar and elevate it, the pawls acting as a toggle-j oint to press the gibs against the lifting-bar.

The retaining mechanism, consisting of the yoke H, pawls I, and gibs J, is the same as just described, except that the yoke H has no bails for lifting it; but in place thereof the yoke H rests on shoulders a of the standard. A forked releasing'lever, K, is pivoted to the standard at k. The prongs of this lever extend through suitable slots made inthe standard and reach under the gibs J. When the lifting-bar B has been elevated, and it is-desired to depress the same, the outer end of the lever O is elevated, and the yoke E is thereby depressed until the lower ends of the gibs G rest upon the sleeve a, by means of which the gibs G and pawls F are slightly elevated and the gibs are caused to release their grip on the lifting-bar. While the parts are in this position, by pressing down on the outer end of the lever K, the prongs thereof are made to lift the gibs J, when the lifting-bar will descend by gravity.

With mechanism as described in the patent aforesaid the pawls come in direct contact with the lifting-bar, and as the contact-surfaces are necessarily limited there is a tendency to abrade the surface of the lifting-bar and even indent the latter when the load is excessive. With my improved device, owing to the large surface of the gibs that engage the lifting-bar, this difficulty is entirely overcome, the result being that the wear of these parts is merely nominal. The gibs and pawls being short and strong, the engaging surfaces of each may be hardened without danger of breakage, and the wear ofthese parts is therefore reduced to a minimum.

What I claim is- 1. In a lifting-jack, the combination,with a standard, a lever pivoted thereto, a liftingbar, and a yoke arranged astride the liftingbar, of gibs and pawls arranged in pairs and supported by the yoke, said gibs being made 5 to clamp the lifting-bar, the pawls being fulcrumed on the yoke and made to serve as toggle-joints in pressing the gibs against the lifting-bar, substantially as set forth.

2. In a lifting-jack, the combination of the x0 lifting-bar, yoke, pawls, and gibs having lugs extending under the yoke for engaging the latter, said lugs serving as stops to prevent the gibs from upward displacement, substantialiy as set forth.

J. WESLEY HAWKINS.

\Vitnesses:

C. R. SAUNDERS, J. B. MILLER.

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