AN IMPROVED GRAVITY MOTOR
Year: 1875

page_text: PROVISIONAL SPECIFICATION left by Alexander Melville Clark at the
Office of the Commissioners of Patents, with his Petition, on the
18th March 1875.-A communication from abroad by John Madison
Cayce, of Franklin, County of Williamson, State of Tennessee,
United States of America.
I, ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, do hereby declare the nature of the
said Invention for "AN IMPROVED GRAVITY MOTOR," to be as follows :—-
The object of this Invention is to enhance the practical value of a
gravity motor by securing the best effects of the attraction of gravitation.
with a comparatively small expenditure of force for restoring the
actuating weight to its original position for a continuation of the motion.
It consists in a weight attached to or near the end of a pivoted
support, which is intermittently shifted from one side to the other of
C shaped springs attached to a rock seat, the said rock seat being
connected by means of a pivoted pawl with ratchet wheel mechanism
and lever which actuates the running gear.
The principle of the operation is that when the weight or support
is out of the perpendicular and resting upon one of the limbs of the

page_text: ← snaped springs, its full weight is imparted through the rock scat, which
acts as a lever to the pawl upon the ratchet wheel, and the running gear
is operated thereby until the rock seat reaches its limit of motion.
When this takes place the weight is, if two pawls are used, shifted to the
other limb of the C shaped spring, or if but one pawl is used is raised
and allowed to come back upon the same side of the spring, but with
the pawl in a position for a new purchase upon the ratchet.
The vital point of the Invention rests in the function of the C shaped
springs.
It is obvious that if the weight is to be lifted by any of the ordinary
devices, there is no gain in power, for the same amount of force is used
in winding up or restoring the weight to its former position as it utilizes
in gravitation. When the rock seat however has reached its limit of
motion and the support and weight is to be shifted, it is only necessary
to apply to the same to accomplish this object a force which is equal to
the difference between the gravity of the weight and the pressure of the
spring upon the same, which will be but a small fraction of its full
effective power, the gravity of the weight and the strength and clasticity
of the spring being so relatively proportioned as to make the weight
almost in a state of equilibrium to any external force.
The motor is composed of a framework having cross pieces which carry
the running gear of any kind of machine. Upon this framework a
support which is made of strong and heavy material is pivoted upon a
rod or bolt passing through the framework. This support is extended in
the form of a screw rod, upon which is placed the weight, the object of
the screw rod being to admit of the adjustment of the weight farther
from or closer to the pivot to increase or diminish the effective power of
the same. The said weight may also be made in sections for the same
purpose and the sections taken off or put on according to circumstances.
Upon the framework is a C shaped spring rigidly and securely attached
to a rock seat, which is pivoted upon the same bolt with the weight
support, but separate and independent from the same; said springs are
made with leaves after the manner of carriage springs, which said leaves
may be made easily detachable, and additional ones put in to strengthen
the spring when the weights are made larger for increased power. Two
pawls are pivoted to the same side of the rock seat engaging at their
lower extremities with opposite sides of a ratchet wheel rigidly attached
to a gear wheel; said pawls have bifurcated ends connected by a pin

page_text: which engages with the ratchets, and the two are held tightly together
upon the wheel by a spring, one pawl operating with a traction and the
other with a pushing motion. I may however dispense with the use of
one of these pawls, in which event the weight will operate in one side of
the spring only.
Attached to the framework are standards in which is journaled a shaft
bearing a cog wheel; to said shaft are also attached arms which pass
through holes in a cross plate on the screw rod to hold on the weights;
said arms are operated by a segment headed lever and constitute with the
latter one of the means for shifting the position of the weight to the
other side of the C shaped springs.
Another means for operating the said weight which is intended to bo
applied to sewing machines, and all other varieties of treadle motion,
consists of an elbow lever attached by means of a connecting rod, and a
piece to the top of the weight, the arm of the elbow lever being connected
by a pitman to the treadle. I do not limit myself to any particular
device for operating said weight for it is obvious that for different
machines different devices will be necessary. It will be observed that
when one pawl is used this only utilizes every other stroke of the treadle,
and brings the weight always back upon the same side of the spring,
which motion may be desirable under same circumstances. The operation
of the device is as follows:-The weight imparts the force of gravity
multiplied according to the character of the leverage through the C
spring to the rock seat, and from thence through the pawls to the
running gear, the motion of the rock seat being limited by stop
projections on the framework; then when it is desired to shift the weight
to the other side of the C shaped spring the gravity of the weight being
nearly balanced by the pressure of the spring it requires but a small
application of new power to change its position to the other side, the
tension of the spring being greatest when the weight is nearest the
horizontal position, and the leverage of the weight being less when it is
near the perpendicular position, or after the spring ceases to be auxiliary
to the shifting of the same; it can be readily seen wherein the advantage
lies.