Improvements in Differential Pulley Blocks.
Year: 1889

page_text: Date of Application, 6th Nov., 1889
Complete Specification Left, 2nd July, 1890--Accepted, 23rd Aug., 1890
PROVISIONAL SPECIFICATION.
Improvements in Differential Pulley Blocks.
JAMES SWALWELL Tredegar Villa, Caeran Park Newport, Mon. Engineer do hereby
declare the nature of this invention to be as follows:-
Upon a fixed eccentric pin, carried by the frame of the pulley block, two chain
wheels of equal diameters and pitch are mounted. One of these chain wheels has an
internal toothed wheel cast on or otherwise secured to it. The other chain wheel has.
cast on or otherwise secured to it a pinion, with a less number of teeth than the
internal wheel: Such number of teeth may be varied to obtain, different speeds
between the two chain wheels. This pinion gears into the internal wheel on the other
chain wheel. An endless chain is passed over the two chain wheels and hangs down
in two loops. In one of these loops a snatch block is placed, the other loop is used as
the hand chain for raising or lowering the load. One side of this loop hangs down
from the chain wheel that has the internal wheel cast upon it. The other from the
chain wheel with the pinion cast upon it, a weight being suspended from the snatch
block. If the chain that hangs down from the chain wheel with the pinion cast upon
it is pulled it will carry the chain wheel with the internal gear with it but at a speed
varying with the difference of teeth between the pinion and the internal wheel. This
varying speed allowing the load to be raised or lowered by pulling the loop used as
the hand chain in opposite directions.
I have described my Invention with chain pulleys of equal diameters but it will be
seen they can be varied to obtain a greater or less difference in speed than is imparted
to them by the pinion, by varying the diameters of the chain sheaves.
Greater power can also be obtained by casting a hand chain wheel of a larger dia.
than the lifting chain wheels and working the same with a separate hand chain, such
hand chain wheel being cast in one piece with or secured to either of the lifting chain
wheels.
Dated this Wifth day of November 1889
COMPLETE SPECIFICATION.
Improvements in Differential Pulley Blocks.
JAMES SWALWELL Tredegar Villa Caerau Park Newport, Mon. 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:
Upon a fixed eccentric pin, carried by the frame of the pulley block, two chain
wheels of equal diameters & pitch are mounted.
One of these chain wheels has an internal toothed wheel cast on, or otherwise
secured to it; the other chain wheel has cast on, or otherwise secured to it a pinion
with a less number of teeth than the internal wheel. Such number of teeth may be
varied to obtain different speeds between the two chain wheels. This pinion gears
into the internal wheel on the other chain wheel. An endless chain is passed over the
two chain wheels and hangs down in two loops. In one of these loops a snatch block
is placed the other loop is used as the hand chain for raising or lowering the load.
One side of this loop hangs down from the chain wheel that has the internal wheel
cast upon it; the other from the chain wheel with the pinion cast upon it; a weight
being suspended from the snatch block.
If the chain, that hangs down from the chain wheel with the pinion cast upon it

page_text: is pulled, it will carry the chain wheel, with the internal wheel, with it; but at a speed
varying with the difference of teeth between the pinion and the internal wheel. This
varying speed allowing the load to be raised or lowered by pulling the loop used as
the hand chain, in opposite directions.
I have described my invention with chain wheels of equal diameters but it will be
seen they can be varied to obtain a greater or less difference in speed than is imparted
to them by the pinion by varying the diameters of the chain wheels.
Greater power can also be obtained by casting a hand chain wheel of a larger
diameter than the lifting chain wheel, and working the same with a separate band
chain; such hand chain wheel being cast in one piece with, or secured to either of the
lifting chain wheels.
The drawings represent a pulley block constructed according to this invention.
Fig. 1 is a side elevation.
Fig. 2 a sectional elevation, and
Fig. 3 a plan.
The same letters of reference are used throughout.
A is the chain wheel with the internal wheel E cast on it.
with the pinion (that gears into the internal wheel E.) cast on it.
carried by the frame. D. is the snatch block.
B is the chain wheel
C. is the central pin
The dotted lines X Y represents the application of the chain. The snatch block
will be raised if the chain is pulled in the direction of the arrows, and lowered if
pulled in the opposite direction.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed: I declare, that what
I claim is
The combination and arrangement of the several parts to form a self-sustaining
differential pulley-block substantially as described and shewn.
Dated this 30th day of June 1890.
JAMES SWALWELL,