Improvements in or relating to Differential Pulleys for Raising Loads at Slow Speeds.
Year: 1892

page_text: Date of Application, 26th Jan., 1892-Accepted, 27th Feb., 1892
COMPLETE SPECIFICATION.
Improvements in or relating to Differential Pulleys for Raising
Loads at Slow Speeds.
A communication by EDWARD YOUNG MOORE, of 94, Nineteenth Street, in the
City of Milwaukee, County of Milwaukee and State of Wisconsin, United
States of America, Manufacturer.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for
Foreign Patent Solicitors, 6, Lord Street, Liverpool, and 6, Bank Street,
Manchester, both in the County of Lancaster, and 323, High Holborn, in the
County of Middlesex, Civil 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:-
This invention relates to a pulley block in which differential gear is embodied;
forming an apparatus for raising and lowering great loads at a slow speed, by means
of a comparatively small amount of power, moving through a much greater space
and preferably at much greater speed.
The object of the invention is to improve mechanism heretofore in use, whereby
friction is obviated, a more desirable differential movement is secured, and the
facility with which the apparatus can be operated is made greater.
In the drawings,
Figure 1 is a view partly in elevation, and partly in vertical section of the
improved device.
Figure 2 is a section on line 2-2 of Figure 1 looking toward the left.
Figure 3 is a top plan view of the device.
Figure 4 is a side view of one of the chain wheels, being the one at the right of
the line 2-2 in Figure 1.
A is the frame of the pulley block, which is of suitable size and form to support
the operative mechanism. The hook B is swivelled in the top of the frame, and is
adapted for suspending the pulley block. An axle C is journalled in the frame, and
is provided with the chain wheel D fixed thereon. An endless chain (not shown
in the drawings) runs on this wheel and is adapted for rotating the wheel by hand,
for operating the mechanism. Two other chain wheels E and F of equal diameter
are loose on the studs or bosses G, which, being pierced centrally by the axle C,
are in the nature of sleeves about the axle, the bosses being integral with or rigid
A chain H
to the frame. The wheels E and F are concentric with the axle C.
runs on the two wheels E and F, the chain being so arranged that it runs over one
wheel as E from front to rear or from rear to front, and is carried diagonally
beneath the wheels to the other wheel F, and runs over that wheel in the same
direction from front to rear or from rear to front. The load is supported con-
veniently by a yoke (not shown in the drawings) attached to the free ends of the
chain, which yoke, supporting the load, rises and falls evenly, the extremities of
the chain to which it is attached being pendent from the wheels on the two sides
of the axle C. It is not necessary that the chain running on the two wheels E
and F should be integral, but instead there may be two chains, one running on
each wheel, it being only necessary that the load is supported on two extremities of
the chain, or chains, one from each wheel, and depending therefrom on opposite
sides of the axle C.
Interposed between the wheels E and F, a cylindrical eccentric I fixed on the
shaft C rotates therewith, and two cog wheels, a greater wheel K and a smaller
wheel L, constructed integrally and concentric with the eccentric I, are thereby
carried around the axle C and rotate on the eccentric on the antifriction rollers M,
These collars M serve merely
interposed between the wheels and the eccentric.

page_text: Fi
as antifriction bearings for the integral double wheel KL. The chain wheel E is
provided with an internal cog wheel gear E' which meshes with the teeth of the
smaller cog wheel L, but the gear E' is considerably larger and contains more
teeth than the cog wheel L does, which number may differ in almost any ratio that
is desired, but which in the drawings are twenty eight in the gear E' and twenty
two in the wheel L. The chain wheel F is provided with an integral gear
which meshes with the cog wheel K, but which is larger and contains more teeth
than the cog wheel K does. This difference in the number of teeth in the gear Fi
and the wheel E may vary as desired, but in the drawings are shown to be thirty
eight and thirty two respectively, so that the difference (ten, in the device shown)
in the number of the cogs on the wheels Land K, is the same as the difference in
the number of cogs on the wheels E and F. The teeth on the wheels E and L
and the teeth on the wheels F and K that respectively mesh with each other, are
constructed with the same pitch, and are so proportioned as not to wedge upon,
strain, or unduly grind each other. These several wheels and their supporting
devices are so constructed and arranged, that the wheels L and K as they roll
around the axle C with the eccentric I are constantly in mesh with the wheels E
and on that side of the axle at which the eccentric has the greatest radius and
are otherwise out of gear therewith. The action of the mechanism is substantially
as follows-
The load suspended on the extremities of the chain H depending on opposite
sides of the axle C from the wheels E and F respectively tends to rotate the
lifting wheels E and F in opposite directions, the integral wheels L and K,
however, meshing with the wheels E and F prevent rotation of these wheels in
opposite directions except to the extent caused or permitted by the rotation of the
integral pinion or wheels L and K about against the wheels E and F. The
eccentric I being rotated about the shaft, puts the teeth of the wheels Land K
successively into mesh with the wheels E and F, until (for example) the wheel K
has completed a. revolution of the wheel F making one and six, thirty seconds
revolutions, which will not carry the wheel L (integral with K) around the
wheel E (as one and six, twenty eighths revolutions of the wheels L and Kare
required to complete a revolution of the wheel E) and the peripheries of the
wheels L and I will have moved with reference to each other fifteen, two-
hundred and sixty-sixths (1884) of a revolution. Thus while the wheels E and F
move differentially actuated by the integral pinion or wheel L and K forcing or
permitting the movement of the two wheels in opposite directions, acting as a
fulcrum on either wheel, and the two wheels E and F thus moving differentially
let off or take up a corresponding portion of the lifting chain, the action of
the pinion and the gravity of the load, cause the wheels E and F to rotate on
their bearings sufficiently to constantly and equally support the load.
This movement of the eccentric and the train of related mechanism is accom-
plished by rotating the wheel D, (by means of the endless band chain, not shown,
running thereon) and it will be understood that, by rotating the wheel D in the
reverse direction, the opposite movement of the load can be obtained.
By reason of the peculiar construction and arrangement of the several wheels
and their bearings in this apparatus, the leverages and resistances are such that
aided by the friction of the mechanism, the weight of the load on the chains
will not reverse the motion of the apparatus, nor permit the load to run down by
its gravity.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, as communicated to me
by my foreign correspondent, I declare that what I claim is
1. The combination with a suitable frame of an axle journalled therein, two.
lifting chain wheels of equal diameter having internal gear wheels of different
sizes, an eccentric rigid on the axle, and two integral gear wheels of different sizes
meshing respectively with the gear on the lifting chain wheels, the gears thus in

page_text: mesh being different in size, whereby, by the rotation of the eccentric, a differential
rotation of the lifting chain wheels in opposite directions is obtained, substantially
as described.
2. In a differential lifting apparatus, the combination with two lifting chain
wheels each provided with gear teeth, the wheels being revolubly loose in the
frame, of an eccentric fixed on an axle revoluble concentrically with the lifting
chain wheels, and two integral cog wheels of unequal diameter loose on the
eccentric, meshing respectively differentially with the lifting chain wheels, sub-
stantially as described.
3. In a differential lifting apparatus, the combination with a frame and two
lifting chain wheels provided with gear and revolubly loose in the frame, of a
cylindrical eccentric fixed on an axle journaled in the frame, two integral cog
wheels of unequal diameter about the eccentric meshing with the lifting chain
wheels, and bearing rollers interposed between the eccentric and the cog wheel,
substantially as described.
4. In a differential lifting apparatus, the combination with two lifting chain
wheels revolubly loose in the frame, each wheel being provided with gear teeth, of
an eccentric fixed on an axle revoluble concentrically with the lifting chain wheels,
and two integral cog wheels of unequal diameter loose on the eccentric meshing
respectively differentially with the lifting chain wheels, and bearing rollers
interposed between the eccentric and the cog wheels, substantially as described.
5. In a differential apparatus, the combination with lifting chain wheels
provided with internal gears having a certain number of teeth, of cog wheels of
smaller diameter and fewer teeth revoluble on and rotatable eccentrically about
the axis of the chain wheels and meshing therewith, and teeth on the wheels
meshing with each other and though different in number having the same pitch,
substantially as described.
6. In a differential apparatus, the combination with a suitable frame, of an
axle journalled therein, an eccentric rigid on the axle, integral cog wheels of
different size revoluble on and rotatable with the eccentric, chain wheels of equal
diameter having internal gears of different sizes and meshing respectively with but
larger than the cog wheels with which they respectively mesh, lifting chains
running on the chain wheels and a suitable load supporting device supported on
two legs of the lifting chains running on different wheels and depending from
radially opposite sides thereof whereby a load on the load supporting device will
not be let down by its gravity, substantially as described.
Dated this 25th day of January 1892.
WM. P. THOMPSON & Co.,
Agents for the Applicant.