IMPROVEMENTS IN WINDLASSES, WHICH MAY BE APPLIED TO PRESSES AND TO OTHER APPARATUS FOR OVERCOMING RESISTANCE
Year: 1864

page_text: PROVISIONAL SPECIFICATION left by Jehiel Keeler Hoyt at the Office
of the Commissioners of Patents, with his. Petition, on the 15th March
1864. A communication from abroad by James Christison, of New
York.
I, JEHIEL KEELER HOYT, of the City, County, and State of New York,
United States, now of No. 12, Southampton Buildings, Chancery Lane, in
the County of Middlesex, Merchant, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN WINDLASSES, WHICH MAY BE APPLIED TO PRESSES
AND TO OTHER APPARATUS FOR OVERCOMING RESISTANCE," a communication, to be
as follows:-
. The nature of my Invention consists-chiefly in the employment of one or
more tapering spiral grooved windlasses for presses and other kinds of
mechanism to overcome resistance. It is well known if a cord or chain be
let off a cylinder of any given diameter and wound upon a cylinder of greater
diameter making the same number of revolutions, such cord or chain will be
gradually absorbed and the free-portion will be contracted with great force.
To obtain a similar result a windlass or windlasses of a tapering form are
employed, by which means also the purchase or mechanical advantage may
be varied to suit the variations in the resistance offered. When two wind-
lasses are employed they taper in opposite directions. Each windlass is
provided with a spiral groove to receive an endless cord or chain which passes
one or more times about the windlass at its smaller end, and may be rove
through a biock or pulley, or pass around the body to be moved. By

page_text: turning the shaft on which the windlasses are fixed the cords or chains are
gradually transferred towards the larger end of the windlasses, each revolution
letting off a coil, and at the same time winding on a coil of greater length.
The taper of the windlasses is not generally uniform, but greater at the larger
or smaller end as the nature of the resistance requires. When the taper is
greater at the smaller end the effect is to raise the body or the bed of a press,
to which the cord or chain is attached, rapidly at first with moderate force,
the speed continually decreasing while the force increases. By making the
larger end of each windlass nearly cylindrical, the mechanical force of the
power applied may be greatly increased near the end of the action, as required
in cotton or hay presses. By making the smaller end of nearly a cylindrical
form, the greatest force may be exerted at the commencement, as may be
sometimes required in crushing obstinate materials, or the same mechanical
advantage may be obtained at any intermediate point between the ends of the
windlass.
In addition to the advantage of a variation of purchase or force by the
irregularity of taper, is the variation that may be obtained in the effect by
the adjustment of the cord or chain upon this windlass. By increasing the
number of coils of the rope around the windlass the speed will be increased
and the force decreased, and by decreasing the number of coils the speed will
be decreased and the force augmented. This effect is due to the difference in
the diameter of the part of the windlass where the rope is coiled on and
where it is let off, and the purchase or force exerted is inversely as such
difference. By the employment of such tapering windlasses with endless
cords or chains the weight is kept suspended when the power is withdrawn,
but any mechanism, such as a wheel and axle, for operating the windlasses
may be thrown in and out of gear without the use of breaks or stoppers of
any description.