An Improved Friction Clutch for Application to the Gear of Lifts, Hoists, Crabs, Winches, and similar Hoisting Machines, whereby may for Quick Descent.
Year: 1893

page_text: Date of Application, 6th Nov., 1893
Complete Specification Left, 5th Sept., 1894-Accepted, 6th Oct.,
1894
PROVISIONAL SPECIFICATION.
An Improved Friction Clutch for Application to the Gear of Lifts,
Hoists, Crabs, Winches, and similar Hoisting Machines, whereby
the Load may be either Sustained or Released for Quick
Descent.
ALEXANDER CHARLES MOFFATT 141 Queen Victoria Street London, E.C.
Engineer, do hereby declare the nature of this invention to be as follows:-
A hollow metal cylinder or drum, the length of which is about equal to its
diameter, on the outside of the body of the said cylinder or drum is cast or affixed
a metal disc, the periffery of which is turned down to form a groove, the said
groove being fitted with a band or friction strap-to which is connected a lever for
tightening or loosening the said friction strap. The outside edges or ends of the
cylinder or drum-that is to say-the ends which are at right angles to the
circumference or body of the cylinder or drum, having V grooves turned thereon.
Two metal discs of similar diameter to the aforesaid metal cylinder or drum-
with central bosses to fit on to a shaft, the said central bosses having segmental
recesses formed therein for the reception of a feather bedded into the said central
shaft and the inner face of each disc-at or near the periffery having V grooves
turned thereon to correspond with and to fit into the V grooves turned on the ends
of the aforesaid metal cylinder or drum-the said metal discs thus forming the two
ends of the said metal cylinder or drum, the outside central boss of one of the
aforesaid metal discs being extended to enable a spur wheel or pulley being affixed
thereto.
The two circular metal discs being connected to each other by means of two or
more chains of equal length passing through the inside of the metal cylinder or
drum as hitherto has been adopted.
Dated this Sixth day of November 1893.
:
ALEXANDER CHARLES MOFFATT.
COMPLETE SPECIFICATION.
An Improved Friction Clutch for Application to the Gear of Lifts,
Hoists, Crabs, Winches, and similar Hoisting Machines, whereby
or Released for Quick
the Load may be either Sustained
Descent.
ALEXANDER CHARLES MOFFATT 141 Queen Victoria Street London, E.C.
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 :-
A hollow metal cylinder or drum, the length of which is about equal to its
diameter: on the outside of the body of the said cylinder or drum is cast or affixed
a metal disc or ring, the periphery of which is turned down to form a groove, the
said groove being fitted with a band or friction strap, to which is connected a lever
for tightening or loosening the said friction strap. The outside edges or ends of
the cylinder or drum, that is to say, the ends which are at right angles to the
circumference or body of the cylinder or drum having V grooves turned thereon.
Two metal discs of similar diameter to the aforesaid metal cylinder or drum ;
with central bosses to fit on to a shaft: the said central bosses having segmental

page_text: recesses formed therein for the reception of a feather bedded into the said central
shaft, and the inner face of each disc at or near the periphery having V grooves
turned thereon to correspond with and to fit into the said V grooves turned on the
ends of the aforesaid metal cylinder or drum; the said metal discs thus forming
the two ends of the said metal cylinder or drum; the outside central hoss of the
aforesaid metal discs being extended to enable a spur wheel or pulley being affixed
thereto.
The two circular metal discs being connected to each other by means of two or
more chains of equal length passing through the inside of the metal cylinder or
drum as hitherto has been adopted.
In order that my said invention may be more fully understood and readily
carried into effect I will proceed to describe the drawings hereunto annexed.
DESCRIPTION OF THE DRAWINGS.
Figure 1 shews a longitudinal section of a drum with its brake strap around
same, and Figure 2 shews an end view partly in section of the said drum with the
brake strap and lever in position; this view being on the line Z Z of Figure 1.
In these figures A is a hollow metal cylinder or drum, on the outside body of
which a recess or groove is formed for the reception of a brake strap.
B and B are metal discs which fit into the ends of the metal cylinder or
drum A.
M is the segmental recess formed in the boss of the metal discs B. B'.
L. L. are feathers bedded into the central shaft E.
C is a brake or strap, connected by pins or studs to a lever H.
N is a rod or bar upon which the lever H is supported.
J is a spring by means of which the brake strap is made to grip around the
groove or recess in the drum A.
K is a link for the reception of a cord or chain, by means of which the grip of
the brake strap C may be released or regulated upon the drum A.
F is a wheel keyed on to the central shaft E, by which rotary motion is given to
the said shaft.
G is a wheel or pinion cast or keyed on to the boss of the metal disc B' for
communicating motion to a train of wheels or pulleys for the purpose of raising or
lowering loads.
The cylinder or drum with the metal ends and connecting chains such as I have
described, have been constructed before, and I do not claim them as novel, but
hitherto the metal cylinder or drum has been held rigidly in its position by means
of stays or rods which prevented it revolving in either direction. A ratchet and
pawl have also been used, which when a load is being raised permits of the metal
cylinder or drum to revolve in one direction only.
In my new arrangement, the metal cylinder or drum is not rigidly held by such
stays, rods or ratchet and pawl, but when required to remain stationary it is firmly
gripped and held by means of the brake or strap and lever as herein described, and
by the releasing of the brake or strap, the metal cylinder or drum is free to revoive
in either direction.
The method by which my new apparatus as herein described is worked is as
follows:-
A rotary motion is given to the wheel F and to the shaft E by means of a
handle affixed thereto, or by means of an endless rope or belt. The pinion G
engages into a spur wheel on the end of a shaft, upon which is fixed a rope
wheel or drum for hauling up a load. The length of the chains D. D is regulated
by means of nuts, so as to allow of a slight clearance or freedom between the metal
cylinder or drum A and the circular metal discs B. B'.
When raising a load the shaft E is revolved by means of motion given to the
wheel F; and the two circular metal discs B. B' and the pinion Gare carried
round by the central shaft E; and when so revolving, the chains D. D are slack

page_text: and in a straight position, that is to say parallel with the central shaft E, but the
metal cylinder or drum A is prevented from revolving by means of the brake or
strap around the said cylinder or drum A.
As soon as a rotary motion ceases to be given to the wheel F, the load which is
being raised, having a tendency to descend, causes a reverse movement to be
communicated to the pinion G which is fixed to, and forms part of the circular
metal disc B¹.
The segmental recess formed in the boss of the circular metal disc B¹ allows the
said disc B¹ to move slightly on the shaft E without communicating a reverse
movement either to the shaft E or to the circular metal disc B at the other end of
the metal cylinder or drum A.
Immediately the reverse movement above mentioned is communicated to the
metal disc B', the chains D. D take a diagonal position, the effect of which is to
shorten the distance between the two metal discs B. B' and thereby causing the
V grooves turned on the inner faces of the two metal discs B. B' to engage with
the V grooves turned on the ends of the metal cylinder or drum A, and thereby
the descent or running down of the load is instantly arrested.
In the arrangement hitherto made use of, when it is required to lower a load, the
wheel F has to be driven in the direction opposite to that communicated to it when
raising a load, so that the same length of time is required for lowering a load as is
required for raising a load.
When lowering loads by my new and improved arrangement as herein described
I release the brake or strap C, and the metal cylinder or drum A is free to
revolve, carrying with it the metal discs B. B' and pinion G, and the load is
lowered by means of the brake or strap C, the speed of the descent of the load
being regulated by the amount of grip given by the brake or strap C to the metal
cylinder or drum A, and thereby dispensing with the necessity of having to
communicate power to turn the wheel F and shaft E when a load is being lowered
as has hitherto been the case.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:
1. The application of a brake or strap to the external circumference of a metal
cylinder or drum substantially as described.
2. My improvement in the sustaining and lowering gear of crabs, hoists,
winches, lifts, and similar hoisting and lowering machines substantially as
described.
Dated this Fifth day of September 1894.
ALEXANDER CHARLES MOFFATT.