Improvements in Driving Gear for Velocipedes and Crank Driven Mechanism generally.
Year: 1892

page_text: Date of Application, 13th Oct., 1892
Complete Specification Left, 28th Mar., 1893-Accepted, 6th May, 1893
PROVISIONAL SPECIFICATION.
Improvements in Driving Gear for Velocipedes and Crank Driven
Mechanism generally.
I, JAMES FINDLAY GUILD, M.I.N.A., of 83 Ancrum Road Dundee, Consulting
Engineer and Steam-ship Surveyor, do hereby declare the nature of this invention
to be as follows:-
This invention relates to an arrangement of mechanism for assisting cranks over
their dead centres, and thereby equalizing the motion of the machine especially
when heavily loaded, as in the case of a cycle ascending an incline, and though
designed more especially for use in connection with velocipedes,
crank driven mechanism of all kinds.
applicable to
This invention consists mainly in the introduction of a spring or springs between
the crank and the shaft or other mechanism driven thereby.
I will now proceed to describe this invention as applied to velocipedes, its
application to other mechanism will be so well understood that any further
description will be unnecessary.
The chain wheel or driving wheel, as the case may be, of the velocipede is
mounted upon the crank shaft, or upon a socket to be fixed on the crank shaft, so
that it may be free to rotate thereon. In the side of this wheel is made an annular
recess or groove to receive a spiral spring suitably bent in a circular form to lie
within the said groove. A cover plate or disc is provided to enclose the said
groove and retain the spring in position. An arm rigidly secured to the crank
shaft or socket is made to project through a suitable slot in the side of the
recess containing the spring and ear against one end of the said spring. The
other end of this spring bears against a projection in the said annular spring
chamber.
It will be seen that rotary motion given to the crank shaft will be conveyed to
the chain or driving wheel, as the case may be, through the intervention of the
spring contained in the annular recess. On the spring receiving the thrust of the
arm occasioned by the downward pressure of either of the treadles it is compressed
in proportion to the power applied. This compression if on a level road with easy
driving is just sufficient to relieve the rider of the concentrated resistance of the
machine. When the machine is being driven hard the recoil of the spring
occasioned by the greater amount of compression carries the crank over the dead
centres without depending upon the momentum of the machine for this purpose as
in the case of machines of ordinary construction. In short this device absorbs the
power given out by the rider during one part of the stroke and gives it
out to the machine during the other part of the stroke.
excess of
In some cases I find it advisable to employ two or more short springs in place of
one long one, these are each operated upon by a separate arm projecting from the
crank shaft or socket, and of course each bears upon a separate projection formed
within the annular spring chamber.
CASTLE SMITH,
Invention" Office, 54, Fleet Street, London, E.C.,
Agent for the Applicant.

page_text: COMPLETE SPECIFICATION.
Improvements in Driving Gear for Velocipedes and Crank Driven
Mechanism generally.
I, JAMES FINDLAY GUILD M.I.N.A., of 83 Ancrum Road, Dundee, Consulting
Engineer, and Steam-ship Surveyor, 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 an arrangement of mechanism for assisting cranks over
their dead centres, and thereby equalizing the motion of the machine especially
when heavily loaded, as in the case of a cycle ascending an incline, and though
designed more especially for use in connection with velocipedes, is applicable to
crank driven mechanism of all kinds.
This invention consists mainly in the introduction of a spring or springs between
the crank and the shaft or other mechanism driven thereby.
I will now proceed to describe this invention as applied to velocipedes, its
application to other mechanism will be so well understood that any further
description will be unnecessary.
The chain wheel or driving wheel, as the case may be, of the velocipede is
mounted upon the crank shaft, or upon a socket to be fixed on the crank shaft so
that it may be free to rotate thereon. In the side of this wheel is made an annular
recess or groove to receive a spiral spring suitably bent in a circular form to lie
within the said groove.
A cover plate or disc is provided to enclose the said
groove and retain the spring in position. An arm rigidly secured to the crank
shaft or socket is made to project through a suitable slot in the side of the
recess containing the spring and bear against one end of the said spring. The other
end of this spring bears against a projection in the said annular spring chamber.
It will be seen that rotary motion given to the crank shaft will be conveyed
to the chain or driving wheel, as the case may be, through the intervention of
the spring contained in the annular recess. On the spring receiving the thrust
of the arm occasioned by the downward pressure of either of the treadles it is
compressed in proportion to the power applied. This compression if on a level
road with easy driving is just sufficient to relieve the rider of the concentrated
resistance of the machine. When the machine is being driven hard the recoil
of the spring occasioned by the greater amount of compression carries the crank
over the dead centres without depending upon the momentum of the machine
for this purpose as in the case of machines of ordinary construction. In short
this device absorbs the excess of power given out by the rider during one part
of the stroke and gives it out to the machine during the other part of the stroke.
In some cases I find it advisable to employ two or more short springs in place
of one long one, these are each operated upon by a separate arm projecting from
the crank shaft or socket and of course each bears upon a separate projection
formed within the annular spring chamber.
And in order that my invention may be more fully understood and carried into
practice I will now proceed to describe the same with reference to the accompanying
two sheets of drawings of which
Fig. 1 is an elevation, and Fig. 2 a cross section of one form of the hereinbefore
described device as applied to the chain wheel of a velocipede;
Figs. 3 and 4 are similar views of a modified arrangement of the same.
As shown at Figs. 1 and 2 a short sleeve a is keyed upon the crank shaft 6 of
the velocipede and carries at one end a radially projecting arm c which is inclined
to the crank shaft at such an angle that its end enters an annular groove or recess d
formed in the face of the chain wheel e. In this groove is placed a helical spring f
bearing at one end against a stop g, formed in one with the chain wheel e, and at
the other against the radial arm c extending from the sleeve a. The spring is

page_text: retained within the groove by the cover plate h which is screwed or otherwise
attached to the face of the chain wheel e. A portion of this plate h is removed so
as to allow of the clear passage of the radial arm c into the groove d. The central
part of this cover plate as shown at Fig. 2 bears against the end of the sleeve a
and so serves to retain the chain wheel e in position.
In the arrangement shown at Figs. 3 and 4 the chain wheel is arranged to
support two springs and the sleeve a is provided with two radial arms cone
to bear against the end of each of the said springs. The cover plate is of
course modified in construction to allow of the entry of the two arms c into the
grooves d.
In other respects the parts are similar to those already described as an
inspection of the drawings will show.
It will be understood that the hereinbefore described device may be placed upon
the axle of a chain wheel with equal success in working, it being only necessary to
reverse the device so that it may rotate in the opposite direction.
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 :-
(1) The interposition of a spring or like device between the crank shaft of a
velocipede or like vehicle and the driving wheel or wheels of the same substantially
as and for the purpose herein before, set forth and described and illustrated in the
accompanying drawings.
(2) The interposition of a spring or like device between the crank shaft and
the mechanism driven thereby in crank driven machinery substantially as and for
the purpose herein before set forth and described and illustrated in the accompanying
drawings.
Dated this 04th 1 of M 1902
66
CASTLE SMITH,
Invention" Office, 54, Fleet Street, London, E.C.,
Agent for the Applicant.