US232846A - Jack-screw - Google Patents

Description

(No Model.)

D. RANKIN.

- Jaok'Screw. No. 232,846. Patented Oct, 5,1880

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DAVID RANKIN, OF SAN FRANCISCO, CALIFORNIA.

JACK-SCREW.

SPECIFICATION formingpart of Letters Patent No. 232,846, dated October 5, 1880.

Application filed June 30, 1880.

To all whom it may concern:

Be it knownthat I, DAVID RANKIN, a subject of the Queen of Great Britain, and residing at San Francisco, in the county of San Francisco and State of California, have invented a new and useful J ack-Screw, of which the following is a specification.

My invention relates to improvements in jack-screws such as are used in the lifting or moving of buildings and other heavy weights; and the objects of my improvements are, first, to provide a jack-screw in which the cap which supports the weight is so constructed as to give a central and not a side pressure to the capstan-head and screw-threaded shaft when being worked on an incline and while the screw-shaft is being revolved or worked; second, to provide a means whereby the screwthreads of the shaft and base are relieved of th erincumbent weight or pressure after the eight has been raised, and all danger of accidents which might arise from the breakmg of the screw-threads is avoided; third, to provide a device whereby the capstan-bar or handspike may be attached to the body of the jack-screw in such manner as to form a handle by which the jack-screw may be carried from place to place; and, lastly, to provide a means whereby the capstan-bar can be operated in a small compass or space.

I attain these objects by the mechanism illustrated inthe accompanying drawings, in which- Figure 1 is a side elevation; Fig. 2, vertical sectional elevation Fig. 3, top viewof cap.

Similar letters refer to similar parts throughout the several views.

The body or base A of my jack-screw I cast in the usual bell-shaped mold, and turn a screw-thread for a short distance in the upper part thereof.

The stem or shaft B of the capstan-head O is provided with a screw thread its entire length, and it engages with the screw-thread of the body A.

The capstan-head G is pierced with two or a double series of capstan-holes, D D, the centers of the upper holes oropenings being over the center of the web, between the lower (No model.)

it is impossible to make any but short turns of the capstan-head.

The top of the capstan-head is constructed in the form of a dome, as clearly seen in Fig. 2, and over this the cap or castle E fits, and is held in position by a bolt or rivet, a. r

The cap or castle is hollowed out, as shown, so as to fit over the top of the capstan-head or dome, and the lower part of this cavity is of greater diameter than the upper part thereof, or of that portion of the capstan-head upon which it rests and covers, the object being to permit the cap to be slightly inclined when operating or working on an incline or uneven ground. 1

Near the upper part of the base A, I secure the knob F, which has an aperture through which the handspike G is passed, and a step is formed near the bottom of the base A, in which the point of the handspike rests. A setscrew, 1), serves to secure the handspike in its position, as shown.

When in operation and the screw-shaft has been turned up a sufficient height, and it is desirable that the superincumbent weight shall remain in a certain position for any length of time, I take the key or bar H, which, when not in use, hangs by a ring upon the knob F, and pass it through any two of a series of slots, I I, cut in the base A, and then reverse the jack-screw a few turns, or until the lower end of the screw-shaft rests upon the said key, and the pressure will then be taken oft the screwthreads and all danger of accident be avoided.

The part of the cap E which is applied to the weightto be operated upon is hollowed out, as shown, and the upper part or rim has a triangular groove, 0, cut therein, so that it may take a firmer hold upon the weight to be lifted, and at the same time not scarify it as when operating with anotched cap.

Having thus described my invention, what I claim, and desire to secure by Letters Patent, is-

1. In a jack-screw, the combination of the capstan-head constructed in. the. form of a dome with the cap or castle hollowed out so as to be received by the said capstan-head in such a manner as to allow of sufficient space for the easy working of the parts when united, substantially as herein set forth and described.

2. In a jack-screw, the combination, with the base A and cap E, of the screw-threaded stem B and dome-shaped capstan-head 0, provided with rivet-bolt a and a series of holes,

and cap E, all arranged andoperating substantially as herein shown and set forth.* I 5 5. In a jackscrew, a carrying or lifting device consisting of a knob or projection, F, setscrew 1), and capstan-bar Gr, substantially as set forth and described.

In testimony that I claim the foregoing I 20 have hereunto set my hand and seal this 2d day of June, 1880.

DAVID RANKIN. n s.]

" Witnesses:

O. W. M. SMITH, W. P. COLEMAN.

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