Improvements in Pulley Blocks, Hoists, Lifts, Crabs and the like.
Year: 1899

page_text: PROVISIONAL SPECIFICATION.
Improvements in Pulley Blocks, Hoists, Lifts, Crabs and the like.
We, CHARLES WILLETTS, Junior, of Colonial Works, Cradley Heath, in the
County of Stafford, Pulley Block Manufacturer, and ALFRED HENRY ROTHAN,
of Trinity Street, Old Hill, in the County of Stafford, Draughtsman and Fitter,
do hereby declare the nature of this invention to be as follows:-
This invention has reference to pulley blocks hoists lifts crabs and the like
and consists of the herein-described improved automatic brake mechanism for
controlling the lowering of the load. Our invention is particularly applicable
to those pulley blocks hoists lifts crabs and the like in which the lifting gear
consists wholly or in part of a worm and worm wheel the worm being mounted
on the hand chain wheel shaft on which our automatic brake which we will
now describe is also mounted.
We will describe this invention as applied to a pulley block.
In carrying out this invention we provide on the said worm shaft a friction
cone which is screw threaded internally to fit upon a corresponding screw thread
formed on the worm shaft, this screw thread being by preference of the opposite
hand to that of the worm which gears with the worm wheel. Upon the worm
shaft there is fixed a coiled spring one end of which is fixed to
the cone and this spring has a tendency to turn the cone and
screw the same against a collar which is formed on the face of the ratchet
wheel and which collar is coned internally to suit the said conc. Gearing with
this ratchet wheel is a click or pawl fixed on one of the stationary cross bars
or bearings of the pulley blocks. The said ratchet wheel is made with a boss
which presses against a hardened steel washer or other suitable bearing surface
fixed in the cross bar or bearing into which the end of the worm shaft fits and
in which there is a steel washer with hardened surface or other suitable bearing
to take the end thrust on the worm shaft.
The automatic brake above described acts as follows:-When the load is
being lifted by the turning of the worm shaft the said cone on the worm shaft
and the ratchet wheel all turn with the worm shaft the ratchet teeth passing
under the click or pawl and the end thrust being taken by the boss at the back
of the ratchet wheel acting against the steel washer in the bearing. Thus the
worm wheel shaft will turn freely when lifting the weight. When the worm
shaft is turned in the opposite direction and the weight is being lowered or when
the weight is suspended and stationary the ratchet wheel and the cone formed
therewith are arrested by the click or pawl and cannot turn back with the
worm shaft and then the friction which is set up between the internal surface
of the cone of the ratchet wheel and the external surface of the cone on the
worm shaft, and also by the end of the worm shaft bearing against the steel
washer or other suitable bearing surface is sufficient to sustain the weight and
allow of its being lowered by a slight pull on the hand chain. As the spring
above described keeps the cone surfaces always in contact the brake acts instan-

page_text: taneously to sustain the load and allow of its being lowered with a slight pull
on the hand chain wheel.
1000
CHARLES BOSWORTH KETLEY,
Agent for the Applicants.
COMPLETE SPECIFICATION.
Improvements in Pulley Blocks, Hoists, Lifts, Crabs and the like.
We, CILARLES WILLETTS, Junior, of Colonial Works, Cradley Heath, in the
County of Stafford, Pulley Block Manufacturer, and ALFRED HENRY ROTHIAN,
of Trinity Street, Old Hill, in the County of Stafford, Draughtsman and Fitter,
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 has reference to pulley blocks hoists lifts crabs and the like
and consists of the herein-described improved automatic brake mechanism for
controlling the lowering of the load. Our invention is particularly applicable
to those pulley blocks hoists lifts crabs and the like in which the lifting gear
consists wholly or in part of a worm and worm wheel the worm being mounted
on the hand chain wheel shaft on which our automatic brake which we will
now describe is also mounted.
We will describe this invention as applied to a pulley block and refer to the
accompanying drawings on which Fig. I is a sectional side elevation of a worm
and worm wheel pulley block with our invention applied; Fig. 2 is a full size
view of part of the worm shaft and our invention; Fig. 3 is a sectional end view
of the same on line XX of Fig. 2 and Fig. 4 shews separately a part of the
cone clutch of the same.
The same letters of reference indicate the same parts in all the figures.
A is the worm shaft having formed therewith the worm B which gears with
the worm wheel C made with a sprocket wheel D over which the lifting chain E
passes; F is the hand chain wheel fixed on the worm shaft A for turning the
same.
In carrying out this invention we provide on the worm shaft A a friction
cone G shewn separately by Fig. 4 which is screw threaded at g' internally to
fit upon a corresponding screw thread a' formed with the worm shaft A this
screw thread being by preference of the opposite hand to that of the worm B
which gears with the worm wheel C. Upon the worm shaft A there is fixed
a coiled spring H one end of which is by the screw I or by other means fixed
to the cone G the other end he of the spring being fixed as by the screw J to
the worm shaft A. This spring H has a tendency to turn the cone G and screw
the same against the collar K which is formed on the face of the ratchet
wheel L and which collar K is coned internally at to suit the cone G. Gearing
with this ratchet wheel L is a click or pawl M turning on a pin N fixed on one
of the stationary cross bars 0 or bearings of the pulley block. The ratchet
wheel L is made with a boss which presses against a hardened steel washer P
or other suitable bearing surface fixed to the cross bar or bearing 0 into which
the end a of the worm shaft A fits and in which there is a steel washer Q with
hardened surface or other suitable bearing to take the end a² of the worm
shaft A.
The automatic brake above described acts as follows:-When the load is
being lifted by the turning of the worm shaft A the cone G on the worm shaft A

page_text: and the coned collar K and the ratchet wheel L all turn with the worm shaft A
the teeth of the ratchet wheel L passing under the click or pawl M and the
end thrust being taken by the boss at the back of the ratchet wheel acting
against the steel washer in the bearing. Thus the worm wheel shaft A will
turn freely to lift the weight. When the worm shaft A is turned in the opposite
direction and the weight is being lowered, or when the weight is suspended
and stationary, the ratchet wheel L and the cone K formed therewith are arrested
by the click or pawl M and cannot turn back with the worm shaft A and then
the friction which is set up between the internal surface of the cone K and
the external surface of the cone G on the worm shaft, and also by the worm
shaft bearing against the steel washer or other suitable bearing surface Q, is
sufficient to sustain, the weight and allow of its being lowered by a slight pull
on the hand chain. As the spring H above described keeps the coned surfaces
always in contact the brake acts instantaneously to sustain the load and allows
of its being lowered by a slight pull on the hand chain wheel.
Our automatic brake mechanism above described is similarly applied to other
pulley blocks and to hoists lifts crabs and the like.
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:-
In pulley blocks hoists lifts crabs and the like, the employment of the improved
mechanism herein described for sustaining and controlling the lowering of the
load, said brake mechanism consisting essentially of the friction cone G which
is screw threaded on the hand chain wheel shaft or handle shaft, the internally
coned ratchet wheel KL mounted to revolve loosely on said shaft and to engage
with the friction cone, the spiral spring H connected to said shaft and friction
cone and arranged to keep the friction cones in contact, bearings to take the
end thrust of the coned ratchet wheel and of the said shaft and a click or pawl
arranged to engage with the ratchet wheel and hold the same stationary when
the load is suspended or being lowered, said parts being arranged and operating
substantially as set forth.
Dated this 18th day of May 1900.
CHARLES BOSWORTH KETLEY,
Agent for the Applicants.