Year: 1888

page_text: United States of America, Mechanic.
I, WILLIAM PHILLIPS THOMPSON F.C.S. M.I.M.E. of the Agency for Foreign
Patent Solicitors 6, Lord Street, Liverpool, and 6, Bank Street Manchester, both in
the County of Lancaster and 323, High Holborn, in the County of Middlesex, Civil
Engineer, do hereby declare the nature of this invention and in what manner
the same is to be performed, to be particularly described and ascertained in and
by the following statement :-
This invention consists in an improved lock for hoisting tackle, hereinafter fully
described and claimed.
Figure 1 is an elevation of the tackle complete.
Figures 2 and 3 are a side view of the upper and lower pulleys.
Figure 4 is a top plan view of the wedge, and
Figure 5 a side elevation of the wedge.
A represents a hook, the shank of which is fastened to a pin B which passes
through the check-plates C of a pulley, and serves to support them.
E and H represent two sheaves journaled on shafts F and G set in the cheek-
plates C, but instead of being placed side by side as usual, they are placed one behind
the other, as clearly shown in Figure 1.
If the pulley is to have more than two sheaves, all but one may be placed side by
side as in the ordinary construction, shown in the lower pulley Figure 3, with one
sheave placed back of one of the others, so that no matter how many sheaves
there are in the upper block, two of them will occupy the relations of the sheaves E
and H.
T and R represent the sheaves of a double pulley of the ordinary construction,
ournaled on the shaft Q and provided with a stirrup P and hook S for attachment to
the load.

page_text: N represents a wedge shaped piece of metal adapted to play between the adjacent
faces of the sheaves E and H, and in its descent to wedge firmly between the rope on
said sheaves.
O represents a shaft journaled in the cheek-plates C, and carrying between those
plates a cam W, which engages with wedge N, so that by rocking said shaft the
wedge N can be lifted away from the sheaves.
D represents a lever secured to the end of shaft. O, by means of which, through a
chain or rope attached thereto, the shaft O can be rotated.
The rope or chain is to be so reeved that the sheaves E H will always turn in
opposite directions, and this may be done as follows:
The running end of the rope I passes above sheave H and then down, as shown
at J, under sheave T, up as shown at L over sheave E, down as shown at K under
sheave R, and then up as shown at M, to its point of attachment to its cheek-plates C).
This point of attachment is shown at one side in the drawing in order to enable the
different lengths of rope to be shown without conflict.
It will be seen that whether the lower pulley is raised or lowered, the sheaves E H
always turn in opposite directions, either toward or away from each other, and the
lengths of rope J and K will always run in the same direction, and will run down-
ward when the lower pulley is descending.
By permitting the wedge N to descend when the sheaves E H are turning
towards each other, and the lengths of rope J K are running downward, it is
evident that the wedge N will be drawn between said ropes and lock them, so as
to hold the ropes stationary, and arrest the lower pulley at any desired point in
its descent.
When the ropes J K run upward, which occurs in raising the lower pulley, the
motion of the ropes lifts the wedge N so that it does not interfere with their
operation, and when it is desired to lower the lower pulley, the wedge N is held up
out of contact with the ropes J K, by depressing the right-hand end of the lever D,
Figure 1, which causes the cam W to lift the wedge N away from the ropes, and
permits the sheaves to rotate freely.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me by
my foreign correspondent, I declare that what I claim is:-
1. The combination with a pulley block having two sheaves arranged one behind
the other to turn in opposite directions, of a vertically movable wedge suspended
between the two sheaves and adapted to wedge between the opposite portions of a
rope passing around the respective sheaves, substantially as described.
2. The combination with a pulley block having two sheaves arranged one behind the
other to turn in opposite directions, of a vertically movable wedge suspended between
the two sheaves and adapted to wedge between the opposite portions of a rope passing
around the respective sheaves, a rocking shaft journaled on the sheave-frame and
having a cam engaging the wedge and a lever D, for rocking the cam shaft, substan-
tially as described.