Improvements in Sprocket Driving Wheels for Cycles and other purposes.
Year: 1897

page_text: PROVISIONAL SPECIFICATION.
Improvements in Sprocket Driving Wheels for Cycles and other
purposes.
We, THOMAS REGINALD VOCE, and BRUCE DRYSDALE, both of Bolton Road,
Small Heath, Birmingham, in the County of Warwick, Manufacturers, do hereby
declare the nature of our said invention to be as follows:-
Our invention has for its object improvements in sprocket driving wheels for
cycles and other purposes by which we are enabled to greatly reduce the friction
which exists in sprocket wheels as at present constructed and also to adjust the
teeth to suit the pitch of the driving chain. We have termed our invention
"The Expanding Chain Wheel."
In carrying our invention into practice we form our sprocket or chain wheels
from two rings between which the teeth are secured. These teeth are pivotted to
the rings and are free to move and adjust themselves to the variations in the
pitch of the chain, each tooth having a projection at one side at its base at right
angles to itself extending around a portion of the periphery of the wheel and
forming a bed for the chain to rest upon which automatically tends to form a
larger diameter than the actual pitch of the chain requires, thus allowing for a
considerable stretch of the chain.
The ends of the projections at the base of the teeth are recessed so as to fit
onto smaller projections formed at the base on the opposite side of the tooth, thus
interlocking each other so that the pressure and pull of the chain on the teeth in
work cause the tooth about to enter the link of the chain to tilt backwards and
the tooth about to leave to tilt forwards allowing the chain to engage and dis-
engage with the least possible friction. The entering tooth is brought into contact
with the link directly the pressure of the chain bears upon the extended portion
at the base of the tooth and the leaving tooth looses contact with the link as the
pressure of the chain ceases upon this extended portion.
If desired we may insert a ring having a serrated edge under the teeth of the
wheel so as to bear against the extended portions of the teeth for the purpose of
permanently enlarging the diameter of the wheel to allow for wear and we may
also insert leather or other soft material into the grooves formed at the ends of
the extended portions of the teeth so as to deaden the sound and lessen the friction.
Dated this 13th day of July 1897.
GEORGE BARKER,
Agent for Applicants, 77, Colmore Row, Birmingham.

page_text: COMPLETE SPECIFICATION.
Improvements in Sprocket Driving Wheels for Cycles and other
purposes.
We, THOMAS REGINALD VOCE, and BRUCE DRYSDALE, both of Bolton Road,
Small Heath, Birmingham, in the County of Warwick, Manufacturers, do hereby
declare the nature of our said invention. and in what manner the same is to be
performed to be particularly described and ascertained in and by the following
statement:-
Our invention has for its object improvements in sprocket driving wheels for
cycles and other purposes by which we are enabled to greatly reduce the friction
which exists in sprocket wheels as at present constructed and also to adjust the
teeth to suit the pitch of the driving chain. We have termed our invention
"The Expanding Chain Wheel."
In carrying our invention into practice we form our sprocket or chain wheels
from two rings between which the teeth are secured. These teeth are pivotted to
the rings and are free to move and adjust themselves to the variations in the
pitch of the chain, each tooth having a projection at one side at its base at right
angles to itself extending around a portion of the periphery of the wheel and
forming a bed for the chain to rest upon which automatically tends to form a
larger diameter than the nominal pitch of the chain requires thus allowing for a
considerable stretch of the chain.
The ends of the projections at the base of the teeth are recessed so as to fit loosely
onto and allow a short oscillation of the smaller projections formed at the base on
the opposite side of the tooth thus interlocking each other so that the pressure and
pull of the chain on the teeth in work cause the tooth about to enter the link of
the chain to tilt backwards and the tooth about to leave to tilt forwards allowing
the chain to engage and disengage with the least possible friction. The entering
tooth is brought into contact with the link directly the pressure of the cham bears
upon the extended portion at the base of the tooth and the leaving tooth looses
contact with the link as the pressure of the chain ceases upon this extended portion.
In order that our invention may be more clearly understood and easily carried
into practical effect we append hereunto a sheet of drawings upon which we have
illustrated sufficient examples to shew the nature of our improved sprocket wheels.
Figure 1 is a front elevation of a sprocket wheel made according to our invention.
Figure 2 is a similar view to Figure 1 with the ring A removed.
Figure 3 is a plan view of Figure 1.
Figure 4 is an enlarged view of one of the sprocket wheel teeth as shewn at
Figure 1.
Figure 5 represents a portion of a sprocket wheel adapted for a single roller
driving chain.
Figures 67 and 8 represent modifications of our sprocket wheels.
In carrying our invention into practice we form the flanges or shrouds of our
sprocket wheels from the two rings A and A' and between these rings we pivot
the teeth T which teeth are free to rock or move and adjust themselves to the
variations in the pitch of the chain. These teeth which we call "lever teeth"
are formed with the tail piece or extended portion t' at their base which forms
that portion of the periphery of the wheel upon which the driving links of the
chain rest and at the ends of this extended portion we form the slot 2. On the
opposite side of the base of these teeth we form, the projections 3 which projections

page_text: take into the slots 2 in the end of the tail piece of the next tooth. By these means
it will be seen that all the teeth interlock each other so that the pressure or pull of
the driving chain on those teeth in work causes the tooth about to enter the link
of the chain to tilt backwards and the tooth about to leave the link to tilt forwards
with the least possible friction. The entering tooth is brought into contact with
the link directly the pressure of the chain bears upon the tail piece t¹ and the
leaving tooth looses contact with the link as the pressure of the chain ceases upon
the tail piece.
At Figure 5 we have shewn our sprocket wheel with the tail piece of the teeth
shortened so as to bring the teeth closer together to form a sprocket wheel suitable
for single roller driving chains. It will be quite evident that instead of forming
the slot ta in the end of the tail piece the projection may be formed at this end,
and the slot 2 at the opposite side near the base of the tooth.
At Figures 6 and 7 we have shewn two modifications of our lever tooth sprocket
wheels. In the method as shewn at Figure 6 we form the tail pieces t and to at
either side of each tooth, one of the tail pieces being slotted at the end and the other
being formed with a projection which takes into the slot in the tail piece of the
next tooth. By this arrangement the tooth will tilt in either direc-
tion. In the modification as shewn at Figure 7 instead of forming the
projection 3 at the base of each tooth we fix the pegs to into one or both of the
inner faces of the rings to which the teeth are pivotted onto which the slotted end
of the tail piece takes the expanding action being exactly similar as previously
described. The inner edge of the shroud A¹ may be turned or flanged inwards
so as to form a stop or rest for the tail pieces and 5 of the teeth as shewn at
Figure 6. Or a projection may be formed on the end of the tail piece of each
tooth and a slotted piece fixed to the inner face of one or both of the rings A or A¹.
These modifications may be applied to the sprocket wheel as shewn at Figure 6.
Or we may fit a cross pin a² at the end of the tail piece of each tooth working in
the slot or slots a³ formed in the rings A & A¹ as shewn at Figure S.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is:-
CLAIMS.
First: The improvements in sprocket driving wheels for cycles and other
purposes consisting essentially in pivotting the teeth T to the flange of the wheel
so that each tooth is free to tilt as it enters and leaves the links of the driving
chain in the manner and for the purpose substantially as hereinbefore described
and as shewn upon the accompanying sheet of drawings.
Second: In sprocket driving wheels forming the teeth T with the extended portion
or tail piece which takes onto or into a projection or slot formed on or in the
next tooth in the manner and for the purpose substantially as herein set forth
and as shewn at Figures 1 to 5.
Third: In sprocket driving wheels which form the subject of the preceding
claims securing a peg or recessed piece to the inner face or faces of the rings A
or A¹ onto or into which the tail end or ends of the teeth take in the manner and
for the purpose substantially as set forth and shewn.
Fourth In sprocket driving wheels forming the teeth T with the extended
portion or tail pieces and to which take onto or into a projection or slot formed
on the tail pieces of the immediate teeth in the manner and for the purpose sub-
stantially as herein set forth and as shewn at Figure 6.
Fifth In sprocket driving wheels forming the teeth T with the extended
portion or tail piece or pieces having a cross pin working and oscillating in a slot
or slots formed in the ring A or A¹ or in both for the same purpose substantially
as herein set forth and as shewn.
Sixth-In sprocket driving wheels as claimed in the preceding claims flanging

page_text: or turning inwards the inner edge of the shroud A¹ for the purpose substantially
as set forth.
Dated this 13th day of April 1898.
THOMAS REGINALD VOCE.
BRUCE DRYSDALE.
By George Barker,
Agent for Applicants, 77, Colmore Row, Birmingham.