IMPROVEMENTS IN MACHINES FOR OVERCOMING RESISTANCE."
Year: 1868

page_text: LETTERS PATENT to Henry Franklin Shaw, of West Roxbury, in
the County of Norfolk, and State of Massachusetts, one of the
United States of America, for the Invention of "IMPROVEMENTS IN
MACHINES FOR OVERCOMING RESISTANCE."
Scaled the 19th September 1868, and dated the 19th March 1868.

page_text: NOW KNOW YE, that I, the said Henry Franklin Shaw, do hereby
declare that the following Complete Specification, under my hand and
seal, fully describes and ascertains the nature of the said Invention,
and in what manner the same is to be performed, in and by the following
statement:-
The nature of my Invention consists in greatly simplifying and
improving that class of power multiplying machines known as
differential gear. It is well known to mechanics, that if a cylinder
having spur gear cut upon its external surface be made to roll upon
spur gear cut upon the internal surface of a second cylinder, the
relative rotary motion of the two cylinders will depend upon the
difference of the relative diameters of the two pitch lines, thus if
the two pitch lines are identical, the two cylinders will have no relative
rotary motion; if they revolve at all they must both revolve with
the same velocity. If we make the pitch line of one smaller than
that of the other and give one of the gears a motion around a central
point, but still so confining it as not to admit of a rotary motion
on its own axis, it will be found that the other gear will be forced
to revolve with a velocity that holds the same relation to the velocity
with which the actuating gear moves as a mass around its central
motion, that the difference between the diameters of the pitch lines
bears to the diameter of the larger pitch line.
By my present Invention I hang both of these gears eccentrically upon
a shaft, which is free to revolve independently of either gear; the gears
themselves are also free to revolve around their own axes, but are hung
eccentrically upon the free revolving shaft. Now if one of these gears
is held and the shaft be made to revolve, it will be found that the
unconfined gear will have a slow motion around its own centre. Again,
if the motion of both of these gears is resisted by an equal force, it will
be found that they will revolve slowly in opposite directions. I take
advantage of this principle by attaching two ropes to the weight to be
lifted or resistance to be overcome, and connecting these ropes, one
to a pulley connected with one gear and the other to a pulley connected
to the other gear, so that when the central shaft is made to revolve the
pulleys act mutually as abutments for each other, and thus overcome
any resistance offered to their tendency to relative motion. As both
pulleys are free upon the actuating shaft, and as the two ropes draw

page_text: In the Drawings Fig. 1 represents a perspective view of
when used as a hoisting gear of an elevator.
my
Invention
Fig. 2 represents a combined pulley and internal gear in plan and
section.
Fig. 3 represents a combined pulley and external gear.
Fig. 4 is a section through both gears.
Fig. 5 represents the actuating shaft.
L, L, Fig. 1, represents the two standards or supporting posts of an
elevator, in which is hung the actuating shaft C, shown enlarged in
Fig. 5. E is a crank for turning the actuating shaft; M, M, Fig. 1,
are hangers for the purpose of giving additional support to the shaft C;
F, P, K, Fig. 1, represent the platform and frame of the elevator
carriage; H is a cross bar attached to the upper bar K of the frame
of the carriage; d, d', are two cords attached to the ends of the bar H,
and to the pulleys A, B. The pulleys A, B, are made as represented,
Figs. 2 and 3, that is, the pulley A. is provided with an external
spur gear Q, Fig. 3, while the pulley B is provided with an internal
spur gear Q', Fig. 2. When in use these two gears and pulleys are
placed together, as shown in Figs. 4 and 5, and hung on the shaft C,
the pulley A. on the eccentric a, and the pulley B on the eccentric b.
By a careful examination of the Drawings and above description,
it will be understood that if the shaft C be revolved, and if an equal
resistance be offered to the revolution of the two pullies, that is, such
a resistance as would be offered by the two cords d, d', Fig. 1, a
differential motion will take place between them, and in case the shaft
is turned in the right direction the weight will be raised, but if turned
in the opposite direction the weight will be lowered. Since the
cords d, d, pull from opposite sides of the shaft C, and that the
gears connected with the two pulleys always mesh together, there will
be perfect equilibrium of strain upon the two cords, that is, one will
act exactly against the other, and there will be no tendency of the
weight to run down, hence in my apparatus I require no pawls or
brakes to hold the weight when partly raised. The necessary relative
eccentric motion can be obtained by a single eccentric on the shaft C,
but the machine does not look so well in operation.

page_text: I claim the two pulleys or winding barrels connected by gears, as
described, eccentrically hung upon a free revolving actuating shaft,
operating substantially as described and for the purpose set forth.
In witness whereof, I, the said Henry Franklin Shaw, have
hereunto set my hand and seal, this Twenty-eight day of i
January, in the year of our Lord One thousand eight hundred
and sixty-eight.
HENRY FRANKLIN SHAW. (L.S.)