provements in Variable Throw Cranks for Road Cycles.
Year: 1897

page_text: Date of Application, 13th Mar., 1897
Complete Specification Left, 11th Dec., 1897-Accepted, 5th Feb., 1898
PROVISIONAL SPECIFICATION
Improvements in Variable Throw Cranks for Road Cycles.
I, HENRY PAYNE, of 39, Court Hill Road, Lewisham, S.E., in the County of
Kent, Engineer, do hereby declare the nature of this invention to be as follows:-
Hitherto extension cranks for road cycles have been made with a hinge joint
in the arm, being held in its minimum leverage position by means of tension or
compression springs. When power is exerted on the crank, the springs are opened
or compressed until the crank has reached its maximum leverage, remaining at
this point until the work done on it is expended, when the springs draw it back
to its minimum leverage again. Their defect is that the springs are affected by
change of temperature, thus becoming liable to break in cold, and to lose their
elasticity in hot weather; also that they are apt to open or break at their
connecting loops. Springs also require a constant tension or pressure to keep
them in their active position, causing useless waste of energy. Such cranks also
give a blow at the time they reach their maximum leverage, thereby causing a
jarring action.
My invention does away with these faults, I substitute in the place of springs,
either a hydraulic, or a pneumatic, or a combination of both arrangements for
assisting the opening and return of the crank to its extreme points, which avoids
the blow resulting from the use of springs.
I use a hydraulic or pneumatic cylinder of any section or shape, one end of
which is attached by a hinge or other suitable moveable joint near the fulcrum of
the lever, the other end of the cylinder has a rod passing through its centre with
a piston attached to the end inside the cylinder, having a hinge or other suitable
moveable joint at the other end of the rod, this joint being attached to the other
end of the lever. I can also use two pistons, one of the rods passing through
each end of the cylinder.
The cylinder has ports passing from the front of the piston when at the maximum
leverage of the crank, to the back of the piston when at the minimum leverage
of the crank; which ports are placed according to whether there are one or two
pistons. The cylinder is filled with a liquid, such as glycerin, oil, etc., or a gas,
such as air, carbonic acid, etc., through a capped opening and check valve by a
pump or any other convenient means. The cylinder must be made tight so as to
allow of no leakage of the substance employed; and this substance is worked under
pressure from one side of the piston to the other, whenever the crank changes its
leverage, through a valve or valves, these valves having bye-pass holes of suitable
size in them to regulate the flow.
When the lever has reached its maximum point, then no extra work is required
to keep it in its position. After removing the driving force, the slightest
resisting force will cause the liquid to flow back to the front of the piston through
the port and the now open valves. The ports can be dispensed with by placing
the valves, with their bye-pass holes, into the piston.
Dated this Thirteenth day of March 1897

page_text: I, HENRY PAYNE, Engineer, of 39, Court Hill Road, Lewisham, 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:-
-
Hitherto variable throw cranks for road cycles have been made with a hinge joint
in the arm, being held in its minimum leverage position by means of tension or
compression springs. When power is exerted on the crank, the springs are opened
or compressed until the crank has reached its maximum leverage, remaining at
this point until the work done on it is expended, when the springs draw it back
to its minimum leverage again. Their defect is, that the springs are affected by
changes of temperature, thus becoming liable to break in cold and to lose their
elasticity in hot weather, also, that they are apt to open or break at their
connecting loops. Springs also require a constant tension or pressure to keep
them in their active position, causing useless waste of energy.
Such cranks also
give a blow at the time they reach their maximum leverage, thereby causing a
jarring action.
My invention does away with those faults. I substitute in the place of springs
either a hydraulic or a pneumatic, or a combination of both arrangements for
assisting and regulating the opening and return of the crank to its extreme points,
which avoids the blow resulting from the use of springs.
I use a hydraulic or pneumatic vessel of round or angular section, one end of
which is attached by a hinge or other suitable moveable joint to one arm of the
jointed crank the other end of the vessel has a rod passing through with a piston
attached to it on one end and a hinge or other suitable moveable joint at its other
end, which hinge or other suitable moveable joint is attached to the other arm
of the jointed crank. The vessel is filled with a liquid such as water, glycerin,
oil etc. or a gas such as air, carbonic acid, etc. through a capped opening and by
some convenient means.
The hydraulic or pneumatic vessel has a port or ports passing from the front
to the back, so that the movement of the piston conveys the liquid or gas from
one end of the cylinder to the other. The rod of the piston goes through a stuffing
box, and the vessel must be quite tight, so as to allow of no leakage of the liquid
or gas employed, and the liquid or gas is forced by the piston through the port or
ports from one side of the vessel to the other by the opening of the crank. When
the lever has reached its maximum leverage and on its upward or return stroke
returns to its original position, a valve or valves in the piston open, so that the
piston meets little or no resistance for its return stroke. In order to regulate the
flow of the liquid or gas and thereby the resistance to the opening of the crank,
the port holes are made of suitable size or byepass holes of suitable size are
provided in the valve or valves. The port or ports can be dispensed with, if the
valves with their byepass holes are put into the piston.
Although my invention will be sufficiently intelligible from the above descrip-
tion, I purpose to show in the accompanying drawing one modification of my
invention, which has proved to give perfect satisfaction, namely one in which
there are no ports and the valve is placed on the piston.
In the accompanying drawings
Figure 1 gives a side elevation of a jointed crank, to which the hydraulic
pneumatic vessel is attached,
or
Figure 2 shows a longitudinal cross section of 'the hydraulic or pneumatic
vessel, and
Figure 3 a full view of the valve Q.

page_text: A and B are the respective arms of the crank, hinged round the point C, which
crank is fitted by means of the cotterpin D to the driving axle at E. The pedal
is fixed at the point Fon to a pin in the usual way. The arm A has a projecting
piece G and the arm 3 a projecting piece H, to which two projecting pieces the
pneumatic or hydraulic apparatus I is jointed by means of pins J and K. The
hydraulic or pneumatic apparatus consists in this case of a cylinder with one fixed
end L, and a screw cap on the other end. The fixed end L has a stuffing box
of the usual construction. The cylinder contains a liquid or gas as stated before.
Through the stuffing box passes a rod N, which is hinged to the arm B of the crank.
The lower end of this rod is screwed and to it screws an annular valve seat 0,
which is held in its place by the nut P. Above the valve seat slides a valve Q,
which has small holes or ports R of such size as required for the resistance it is
desired to effect. The movement of the valve Q is limited by means of an adjust-
able nut S and locknut T.
The working of the crank is now as follows; When the arm B is opened into the
position shewn by the dotted lines, the rod is drawn out from the cylinder, the
valve is pressed on to its seat by the resistance of the liquid and only as much
liquid can go to the back of the piston as the byepass holes will allow, thereby
producing a gradual opening instead of a sudden one. When the crank returns
to its original position, then the resistance of the liquid or gas at the back of the
piston will lift the valve from its scat thereby forming a large opening, through
which the liquid or gas can flow without resistance, so that the slightest pressure
or weight on the pedal will cause the rod and piston to slide back into their
original position.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare, that what I claim
is:-
The application of a hydraulic or pneumatic arrangement for regulating the
opening and return of jointed variable throw cranks on road cycles substantially
as hereinbefore described.