Improvements in Brakes for Hoisting Machinery.
Year: 1896

page_text: Date of Application, 15th Dec., 1898
Complete Specification Left. 13th Sept. 1897-Accepted. 6th Nov.. 1897
PROVISIONAL SPECIFICATION.
Improvements in Brakes for Hoisting Machinery.
We, GEORGE WALKER of 95 Leadenhall Street London, Engineer, and ALFRED
HILLYARD MITCHELL of 67 Elliscombe 'Road, Old Charlton, Kent, Engineer, do
hereby declare the nature of this invention to be as follows:-
In Winches, Cranes, and other Hoisting Appliances, when the load has been
raised to the required height, it is frequently necessary to retain the load at the
height lifted, while the engine is thrown out of gear from the lifting apparatus,
to be used for some purpose, such as slewing or travelling the load, or other
purpose.
This brake is generally worked by a band, passing over a brake wheel, and
connected by a lever in such a way, that when the end of the lever is actuated
by the driver pressing upon it, the band is pressed closely to the brake-wheel,
thereby causing sufficient friction to prevent the load pulling the gear round,
and thereby lowering itself when the engine is disconnected.
When heavy loads are being lifted, this brake sometimes fails to act in con-
sequence of the man not being able to put sufficient pressure upon it.
According to this invention, we provide a means of working the brake, and
compressing the brake-wheel, by means of power other than that mentioned
above.
For this purpose, a steam cylinder, or hydraulic ram, or electro motor, or an
electro-magnet, is connected with the brake band, either direct or by gearing in
such a manner that when the steam, water or electric current be applied, it causes
a considerable force to act on the brake band and wheel, and sets up so much
friction between the hand and the wheel, that the heaviest load the crane or hoist
would lift, is not sufficient to overcome it, and the result is the load remains
suspended. To prevent too sudden a strain being thrown upon the brake-band,
a spring buffer is introduced to more gradually apply the pressure.
The force is applied in the case of steam, or water, by opening a valve and
admitting it to the cylinders, and in the case of the electrical appliances, by
coupling up the current by a switch, or other contact maker. So long as
the valves are left open, or the current left on, the brake will be applied, and the
driver can leave the machine if necessary. On releasing the brake, to lower the
load, the steam or water supply is cut off by closing the valve, and another valve
is opened to allow the exhaust steam or water to escape. In the case of the
electrical appliances the current is broken, and the magnets thereby lose their
magnetism to such an extent that the brake is released.
DL 15th day of December 1896.

page_text: Improvements in Brakes for Hoisting Machinery.
We, GEORGE WALKER of 95 Leadenhall Street London, Engineer, and ALFRED
HILLYARD MITCHELL, of 67 Elliscombe Road, Old Charlton, Kent, Engineer, do
hereby declare the nature of this invention and in what manner the same is to
he performed, to be particularly described and ascertained in and by the following
statement:-
In Winches, Cranes, and other hoisting appliances, when the load has been
raised to the required height, it is frequently necessary to retain the load at the
height lifted, while the engine is thrown out of gear from the lifting apparatus,
io be used for some purpose such as slewing or travelling the loal, or other
purpose. This brake is generally worked by a band passing over a brake wheel
and connected by a lever in such a way, that when the end of the lever is
actuated by the driver pressing upon it the band is pressed closely to the brake
wheel, thereby causing sufficient friction to prevent the load pulling the gear
round, and thereby lowering itself when the engine is disconnected.
When heavy loads are being lifted this brake sometimes fails to act in con-
sequence of the man not being able to put sufficient pressure upon it.
According to this invention, we provide a means of working the brake, and
compressing the brake wheel, by means of power other than that mentioned
above.
For this purpose, a steam cylinder, or hydraulic ram, or electro motor, or an
electro magnet, is connected with the brake, either direct or by gearing, in such
a manner that when the steam, water or electric ourrent be applied, it causes a
considerable force to act on the brake band and wheel, and sets up so much friction
between the band and the wheel, that the heaviest load the crane or hoist would
lift, is not sufficient to overcome it, and the result is the load remains suspended.
To prevent too sudden a strain being thrown upon the brake-band, a spring buffer
is introduced to more gradually apply the pressure.
The force is applied in the case of steain, or water, by opening a valve and
admitting it to the cylinders, and in the case of the electrical appliances, by
coupling up the current by a switch, or other contact maker. So long as the
valves are left open, or the current left on, the brake will be applied, and the
driver can leave the machine if necessary.
On releasing the brake, to lower the load, the steam or water supply is cut off
by closing the valve, and another valve is opened to allow the exhaust steam or
water to escape.
In the case of electrical appliances the current is broken, and the magnets
thereby lose their magnetism to such an extent that the brake is released.
In order that our said invention may be more fully understood and readily
carried into effect we will proceed to describe the drawings hereunto annexed.
Figures 1 and 2 are front elevations.
Figures 3 and 4 side elevations.
Steam or water is admitted through the pipe SP and the valve V into the
cylinder C which acts upon the piston P forcing the piston rod PR downwards
compressing the lever L and tightening the brake band BB round the brake
wheel BW.
L has a fulcrum at any convenient part, as at F, and B B is fixed by one end
to some part of the lever, and at the other end to some convenient part of the
machine.
The valve V is a 2 way valve, and when one way is open, the other is closed,

page_text: so that when steam is admitted, the exhaust is closed, and when steam is cut off
the way from the cylinder to the air is open.
Where necessary to prevent too sudden a pressure upon L a spring S is
introduced either inside the cylinder as in Fig. 2, or outside as in Fig. 1.
In the first case the power is transmitted to L by the PR and the cross-
head CH, S acting as a buffer inside.
In the second case the power is transmitted through PR and the Spring, the
ends of which are fastened respectively to the piston rod PR, and the lever L.
In cases where PR acts directly upon L a crosshead CH fitted with a roller R is
fitted, or a connecting link between L and PR may be substituted, or a slot cut in
I in which a pin attached to PR can slide, or the pin may act directly upon the
top of Leach and all being a process to allow L to more freely about its fulcrum.
In the case of the electro motor:
Fig. 5 is a front and Fig. 6 is a side elevation. A is an armature of Soft Iron
fastened to the lever L. SIC is a Soft Iron Core wound round with a coil of
insulated wine CW, when a current of electricity is sent through CW becomes a
magnet and attracts the armature A, which pulls down the lever L tightenin
the Brakeband as heretofore described. When the current is broken or cut off
SIC loses its magnetism and the lever is released.
Having now particularly described and ascertained the nature of our said
invention, and in what manner, the same is to be performed, we declare that what
we claim is:
(1) Brakes for Hoisting appliances in which the brake band is compressed
upon the brake wheel by means of a steam or hydraulic cylinder either direct or
by a lever or levers or other gearing substantially as described.
(2) Brakes for Hoisting appliances in which the brake band is compressed upon
the brake-wheel, by means of an electro magnet acting upon an arurature which
is connected to the brake band either direct or by a lever, or levers or other
gearing, substantially as described.
(3) Steam or Hydraulic cylinders fitted with an internal or external spring,
a two way valve for admitting and cutting off the stean or water, a piston cross-
head fitted with a roller, when used in connection with a brake of a hoisting
appliance either direct or by means of a lever or levers or other gearing,
substantially as described.
(4) Steam, Hydraulic, or Electric appliances fitted to the brake bands of hoist-
ing appliances either direct or by means of a lever or levers or other gearing
substantially as described and shewn in the drawings.
Dated this 10th day of September 1897.
GEO. WALKER.
ALFRED HILLYARD MITCHELL.