A NEW OR IMPROVED MESSENGER SHACKLE BLOCK
Year: 1858

page_text: LETTERS PATENT to George Gilmour, of the State of Massachusetts, of
the United States of America, for the Invention of "A NEW OR IMPROVED
MESSENGER SHACKLE BLOCK."
Sealed the 11th June 1858, and dated the 22nd April 1858.
COMPLETE SPECIFICATION filed by the said George Gilmour at the Office
of the Commissioners of Patents, with his Petition and Declaration, on
the 22nd April 1858, pursuant to the 9th Section of the Patent Law
Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, BE IT KNOWN,
that I, GEORGE GILMOUR, of the State of Massachusetts, of the United States.
of America, have invented "A NEW AND USEFUL OR IMPROVED MESSENGER'
SHACKLE BLOCK," and I do hereby declare that the nature of my Invention,
and the manner in which the same is to be performed, are fully described and
represented in the following Specification, and the accompanying Drawings, of
which Figure 1 is a front view, Figure 2, a side elevation; and Figure 3, a
longitudinal and central section of the same; Figure 4 is a side view of the
bolt on which the pawl turns; Figure 5 is an edge view of the pawl, shewing
the recess therein for the reception of the stud of the pawl pin, all which will
be herein-after explained.
The object of my Invention is to enable a purchase block to be connected

page_text: with a chain cable, when such may be attached to an anchor, a vessel or
other article, and particularly when said chain cable may be under water.
In the Drawings, A exhibits a pulley, provided with three or any number
of sheaves x, x, x, and so connected with a roller B, by extensions c, c, of
the pulley frame, that there may be a chain space or passage D between
the said roller and pulley, the roller turning on a pin or bolt E, passing
througli the parts c, c, and held in place therein by a key b, the same being
arranged as shown in the Drawings. Between the sheave or sheaves of the
pulley and the chain passage D, a pin F extends through the pulley frame,
and serves as a journal or fulcrum of a bifurcated pawl G, which turns on the
said pin, and across the chain space or passage D, and from the roller B back
toward and nearly up to the sheaves, or until certain shoulders c, c, (made in the
edge of the pawl, see Figs. 5, 6, and 7, Fig. 6 being a top view of the pawl,
and Figure 7 another edge view-of it), are made to abut against the frame.
In constructing the frame, the parts c, c, instead of being immovable with
respect to the remainder of the frame, may be separate therefrom and hinged
thereto, that is, the pin F may extend through the said parts, they being
separate from the remainder of the frame, as shewn in the Drawings. Such
pin F where it passes through one of the parts c, or that which is adjacent to
its head y, is made square or polygonal in transverse section, and so as to fit
a corresponding square or polygonal hole formed in the said part c, as shown in
Figure 8, which is an inner side view of the part c. This will cause the pin
to turn or move with the two parts c, c. The remainder of the pin F, or
that part which passes through the pawl, is formed cylindrical, and with a
screw D to receive a holding nut e. Furthermore, a curved recess f, is made in
one edge of the pawl, as shown in Figure 5, and receives a stud g extended from
the pin F, the same being applied or arranged together, so that after the pawl
has been raised upward into about a right angle, with a plane passing through
the axis of the pin F and that of the sheaves, such pawl by its action of the
stud, and when moved further toward the sheaves, shall move the parts c, c, into
the angular position with respect to the pulley, as shown by dotted lines in
Figure 2.
From the above it will be seen that the pawl is thus made to operate as a
lever to move the parts c, c, up to certain stops h, h, fixed on the side of the
pulley, or projecting therefrom, as shown in Figures 1 and 2. The pulley may
have an eye I, for the purpose of connecting it with one end of a purchase
rope, when such is run through the pulley and around its sheaves.
In explaining the mode of using my Invention, we may suppose a chain
cable, or a rope connected with the same, to be suspended from a vessel at

page_text: the surface of the water, and to extend down into the water, and that it is
desirable to clutch the messenger shackle block thereto. Now, this chain may
be a short one connected with an anchor that may rest on the ground under
water, or it may be a chain extended upward from a sunken vessel, or any
other object beneath the surface of the water, and which it may be desirable
to raise upward.
In applying the shackle block to such chain, we should first remove the
roller B from the parts c, c, so as to enable the chain to enter the passage D.
It having been introduced into the said passage as shewn in Figure 2, the
roller should be restored to its place. This having been accomplished, the
block is to be lowered down on the chain, or on the rope to and on the chain,
to the distance required to clutch the two together, the pressure of the chain
against the pawl causing the said pawl not only to slip freely on it, but to
raise the parts c, c, on the rollers, so as to facilitate the passage of the block
on the chain. As soon as the block has attained the depth required, the pur-
chase rope may be operated so as to raise the block, such causing the pawl G
to so pass between the links of the chain and rest against the roller as to
firmly clutch or fasten the block to the chain. The further use of this block
apparatus and its utility will be apparent to most nautical men.
What I claim as my Invention is, the said messenger shackle block, or
combination and arrangement of the sheaves or pulley, the forked pawl,
the roller, and the chain space or passage, substantially as herein-before
specified.
I also claim binging or jointing the parts c, c, and the pawl to the re-
mainder of the frame, in order that the roller and pawl may be turned toward
the sheaves of the pulley, as specified.
I also claim combining with the pawl and the pulley frame a mechanism
substantially as described, or its equivalent, by which, by pressure of the chain
against the pawl, such pawl may be caused to lift the parts c, c, and the roller
in manner, and to facilitate the movement of the shackle block on the chain,
as specified.
In testimony whereof, I have hereunto set my signature and affixed seal,
GEORGE GILMOUR, (L.S.)