US199660A

US199660A - Improvement in derricks

Info

Publication number: US199660A
Authority: US
Publication date: 1878-01-29
Anticipated expiration: 1895-01-29

Description

T. POWELL. Derrick.

No. 199,660. Patented Jan. 29, 1878.

U ITED; STA E THOMAS POWELL, on stro'cKromjoALin-oRNIA.

IMPROVEMMENTIN' DERRICKQS.

Specification forming part of Letters Patent No. 199,660, dated January 29-, 1878; application filed October 9, 1877.

ing purposes.

My invention consists in so applying the ropes which sustain the boom and hoist the load that they will form a truss to stiffen and strengthen the mast, so that the heavier the load the more perfectly will the truss brace the mast, thus allowing me to use a light mast, as hereinafter more fully described.

Referring to the accompanyingdrawings, let A represent a mast which is stepped in two bars or timbers, B C, which cross each other at right angles at its base. Shoes D D are applied to the under side of the bar B, while the forward end of the bar 0 is beveled to form a sled, on which the derrick can be moved, thus providing a broad base, with fac'ilities for moving the derrick easily.

Spliced braces connect each end of the two bars with the mast. These braces are made connected, and the upper parts are folded upon the mast, while the lower parts arefolded upon their respective ends of the cross-bars.

I is an arm, which I secure upon one'side of the mast, near its top, so as to project to a distance from it. K is a boom, which is hinged to the mast opposite the arm I. This boom loperate by a rope, L, one end of which is attached to the boom near its outer end.

The rope then passes over a sheave or pulley,

M, near the upper end of the mast, then down over a sheave or pulley, N, in the outer end of the arm I, thence down to the base of the derrick, to which it is fastened. This arrangement of the rope causes it to serve as a truss to stiffen the mast, because any strain on the outer end of the boom will draw upon the cord, which will throw the weight upon the mast and arm.

The hoisting-rope O has one end securedto the eye X on the under side of the boom, near its outer end, and passes around a pulley, P, at the extremity of the boom, thence up over a pulley, Q, at the top of the mast, and down around a pulley, R, in the outer end of the arm I, outside of the pulley N, thence down around the pulley S.

Two pu1ley-blocks,T T, each of which has a hook on'its under side, are arranged to travel in the bight of the rope O on the under side of the boom, between its attachment to the eye and the pulley P. These hooks are used for attaching the blocks to the load to be lifted, which, in a farm-derrick, will usually be a netting, such as is used for unloading a headerwagon at a single operation. In this'case one of the hooks will be attached to each side of the net. This arrangement will facilitate the operation of attaching the net tothe hoistingblocks, so that it can be hoisted, as the hooks can be separated and hooked upon the net without drawing its side together. The subsequent drawing upon the rope will then close the net upon its load. By using these two travthey can be shifted up or down upon the mast,

as desired.

Awire rope can be used for the rope L. By this arrangement I am able to construct a light derrick, and strengthen it so that it will lift loads that an untrussed derrick of this character and size would not sustain, and, as lighthaving one end attached to the eye X, and

passing around the pulley P,thence over the pulleys Q R, of the locks T '1, arranged to travel in itsbight, substantially as and forthe purpose described.

In witness whereof I have hereunto set my hand and seal.

THOMASPOWELL.

Witnesses: J. B.WEBsTER,

FRANK A. BROOKS.