Improvements in the Gear Chains of Bicycle's, and in the Sprocket Wheels therefor.
Year: 1898

page_text: Date of Application, 21st Apr., 1898
Complete Specification Left, 28th Dec., 1898-Accepted, 25th Feb., 1899
PROVISIONAL SPECIFICATION.
Improvements in the Gear Chains of Bicycle's, and in the Sprocket
Wheels therefor.
I, HAROLD DENNIS TAYLOR, of Trenfield, Holgate, York, Astronomical Instrument
Maker, do hereby declare the nature of this invention to be as follows:-
The sole object of my invention is to reduce the friction which is incidental to the
use of the ordinary gear chains which connect the crank axle of a bicycle with the
rear or driving wheel. This friction & consequent loss of power occurs principally in
the joints of the chain, which offer a certain amount of resistance to bending when
the chain curves itself round either of the two sprocket wheels.
There is also a certain amount of rubbing friction taking place between the joints
or blocks of the chain and the teeth of the sprocket wheels when the links either
settle down upon or leave the sprocket wheels.
In the accompanying drawing Fig. 1 shows a vertical section A & a sectional
plan B of two half links of a block chain, so constructed as to obviate nearly all the
friction incidental to the bending of the joints. The two holes bored through the
two ends of the block b, instead of fitting the rivets d, which are fixed in and
connect the side plates c, are considerably larger so as to leave room between the
rivets & the block for a set of small steel rollers, as shown endwise in A. These
rollers are short pieces of hard steel wire about inch long and about th of an inch
thick. Thus each joint of the chain works on a comparatively frictionless roller
bearing.
The larger Fig. 2 shews a few links of another form of my chain which is provided
not only with frictionless joints e, e, e on roller bearings, but also, placed half way
between the joints, the hollow rollers f, f, f, also rotating on roller bearings.
A vertical section and a sectional plan of a complete link are shown at 8, showing
the hollow roller f rotating on roller bearings about the rivet g, which is fixed firmly
in & connects the two side plates to about their middle. Firmly fixed between and
at one end of the two side plates, & practically forming one piece with the latter, is the
hollow ferrule i. The other ends of the two side plates are firmly connected together
by the fixed rivet j. This passes through the middle of the hollow ferrule i, of the
next link &, in the annular space between the rivet of one link and the ferrule of the
other are placed a set of wire rollers. The interval between the broadened out side
plates of each link is made a trifle wider than the width across the ferrule & side
plates (i,) of the next link which they embrace, so as to obviate rubbing when the
joints bend.
Thus the chain consists of complete links of about one inch pitch joined together
by almost frictionless roller bearings. The teeth of the sprocket wheels are not
supposed to touch the fixed ferrules which form the chain joints but only to engage
with the loose intermediate rollers f, f &c. which can roll on & off the flanks of
the sprocket wheel teeth with extremely little friction.
At T is shown the back sprocket wheel 2 a complete link in position showing
how only the central roller is resting on the sprocket wheel & driving forward the
tooth of the latter. Thus in the case of the back or hub sprocket wheel, when

page_text: the chain is transmitting power to the sprocket wheel, of course the teeth of the
latter must engage into the spaces in front of & immediately preceding the
rollers; whereas in the case of the large front sprocket wheel, when the latter is
driving the chain, of course the teeth of the sprocket wheel must engage into
the spaces immediately behind the rollers, as shown. In both cases there are
cogent reasons for keeping the ferrules forming the joints of the chain quite clear
of the sprocket wheels, as shown. It is only when back pedalling that the ferrules
or chain joints would come in contact with the opposite flanks of the teeth.
This construction of chain requires a form of tooth, especially on the hub sprocket
wheel, which is, as may be gathered from the drawing, much stronger & better
adapted to receive or give a direct thrust, without slip, than the usual form of tooth.
I leave the more precise details of pitch, form & dimensions of side links, rivets,
rollers & sprocket wheels to be set forth in my Complete Specification after
they have been more perfectly ascertained by enquiry experiment.
Data L
11 1
1000
Improvements in the Gear Chains of Bicycles, and in the Sprocket
Wheels therefor.
I, HAROLD DENNIS TAYLOR, of Trenfield, Holgate, York, Astronomical Instru-
ment Maker, 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 :-
The chief object of my invention is to further reduce the loss of power through
friction which still attends the present day safety bicycle or tricycle. This greater
immunity from friction & consequently greater ease of propulsion is attained by a form
of driving chain, for transmitting the rider's power from the crank to the back wheel,
which is shown on Sheet 1 of the accompanying drawings, which also show the proper
forms of sprocket wheel teeth which are designed to work in a frictionless manner with
my form of driving or connecting chain. The first form of my chain is shown in
Fig. 1 in side elevation, in Fig. 1 in longitudinal section and in Fig. 1° partly in
plan and partly in horizontal section. It consists of alternate broad and narrow
links jointed together. The pitch, or distance from the centre of one joint to the
centre of the next joint is 1 inch. The two side plates e of the broad links are
firmly fastened together and opposite one another partly by the two end rivets or
joint rivets v, whose ends are slightly shouldered down for entrance through the side
plates and then fixed by hammering out. The two side plates d of the narrow links
are firmly fastened together and opposite one another partly by the two end ferrules f,
which are slightly shouldered down for entrance into the enlarged and perforated ends
of the side links d and there hammered in. The centres of every pair of side plates
whether forming broad links or narrow links are also joined together by another
rivett also shouldered through the side links and hammered in. These centre rivets t
form pivots to carry the driving rollers r, r, which consist of short pieces of steel
tube, of about the same calibre and outside diameter as the joint ferrules f &
preferably weldless, rotating about the central rivets t on roller bearings, consisting of
a series w of about 12 pieces of hard steel wire of the same length as the roller. Also,
between the end rivet or joint rivet v of one link and the hollow ferrule f of the next
link through which it passes, are placed a similar series w of about 12 pieces of hard
steel wire of the same length as the ferrule, to form a frictionless roller bearing for
each joint of the chain. This idea of applying roller bearing joints to a gear chain

page_text: is not novel as I supposed it was when drawing up my Provisional Specification. The
novelty of this invention consists principally in the mounting in the centre of every
link of a driving roller mounted on roller bearings, whose office it is to receive the
thrust from or transmit the pull to the sprocket wheel teeth, neither flanks nor
bottoms of these teeth being allowed to come into working contact with the joints or
ferrules of the chain during the course of normal or forward driving of the bicycle. It
can be shown that the noiselessness of this chain depends very intimately upon this
condition. The sprocket wheel teeth in such case only engage with the driving
rollers r,, '.
In the mutual working together of the sprocket wheels aud gear
chain of a bicycle there are two sources of friction, 1st, the friction attendant upon the
bending of the chain joints as the chain winds on or off the sprocket wheels and 2nd,
the friction caused by the rubbing of the ends of the chain links against the flanks of
the sprocket wheel teeth as they settle down between them. For the purpose of
obviating friction of the first description the well known Morse rocker chain was
brought out, while for the purpose of obviating friction of the second description
various roller chains of well known names have been introduced. From what precedes
it will be seen that the chain described herein is designed to obviate both descrip-
tions of friction in a very perfect degree and more especially when the teeth of the
sprocket wheels are carefully cut to the shapes shortly to be described. It is a fact
that nearly all the teeth of sprocket wheels now in the market are far too wedge
shaped and have therefore a tendency to thrust the chain outwards, especially if it be
a roller chain.
Reference to B, the back sprocket wheel, in Sheet 1, makes clear the more advan-
tageous form of tooth which is rendered possible by my plan of placing the driving
rollers in the centre of each link halfway between the chain joints. Here the
chain is supposed to be pulling the back sprocket wheel round from left to right
and the driving rollers consequently fall behind the teeth, as shown, while the
ferrules or joints do not necessarily touch the wheel at all. Supposing the
sprocket wheel to be stationary and the chain unwound from it either way it is easy
to determine what are the limiting forms of the teeth which will allow the chain
to wind on and off with perfect freedom. First of all the base of the tooth at
having to fit the driving roller should be a hollow cylindrical surface of about 90
degrees extent of same radius as the roller r, while the upper part of its back
surface should theoretically be a segment of a convex cylinder, the centre of its
curvature being the centre of the chain joint or ferrule f next in front of it. But,
for the sake of giving a little clearance I place the centre of curvature of the upper
flank ha very little below the centre of the said ferrule. But supposing the centre
of the said ferrule to be the centre of curvature for the upper flank h, then the
consequence is that the line n, which is a tangent common to the two curves at the
point where the concave curve 9 of the lower flank merges into the convex curve h
of the upper flank, passes somewhat to the front of the centre of the sprocket wheel.
In other words the back flank of the sprocket wheel teeth just where they receive
the full pull and impact of the driving rollers are somewhat under cut and con-
sequently there is no tendency whatever for the rollers r, to roll up the sides of
the teeth and the chain to wedge off. Whereas it can be shown that an ordinary
chain, driving by its joints, requires slightly over-cut or wedge shaped teeth.
Moreover the fact that the teeth need not be cut out so deeply on their front
faces as upon their rear faces, owing to the ferrules or joints flying further away
from the centre of the sprocket wheel than the rollers, leads to a stronger form of
tooth.
Turning now to the large or driving sprocket wheel it can be shown that the front
flanks of the teeth which drive forward the rollers may also be slightly undercut, and
the same immunity from any wedging off action be secured. The mutual tangent to
flank and base of a tooth is shown at N-N.
It will be clearly seen (from the above) that this chain must be so placed upon the
sprocket wheels that the teeth of the large or driving sprocket wheel come behind
the rollers 7 and the teeth of the back or driven sprocket wheel come in front of the

page_text: rollers r. Thus the teeth work only in contact with the rollers of the chain while
the ferrules or joints of the chain only come into actual play with the teeth in the
course of back pedalling when the slightly increased friction ensuing is an advantage.
Another or second form of my chain is shown in Fig. 24 in side elevation, in
Fig. 2 in longitudinal section and in Fig. 2° partly in plan and partly in
in horizontal section. Here all the links are alike and each link self contained, a
result obtained by elbowing the side plates d, and this is no doubt the best and
cheapest way of making the chain provided that the side plates are made strong
enough at the elbows to withstand any tendency to straighten out under severe
tension. Precisely the same sprocket wheels will do for both forms of the chain.
The same letters apply to corresponding parts in the figures of both forms of
chain.
If the chain is carried out as in Fig. 1 then, if the whole chain consists of an even
number of links there is no difficulty about coupling, but if there is an odd number
of links then a special coupling link like the one on extreme right in Fig. 1 B and C
must be provided.
This slight disadvantage does not attend the other form shown in Fig. 2. A small
ferrule m may be slipped round the connecting pin in place of a set of rollers. All
the sprocket wheels or segments thereof shown in both Sheet 1 and Sheet 2 are
correctly drawn and if the two drawings are carefully copied by photography and
enlarged or reduced as the case may require until the scale of inches on each drawing
is made to read to inches exactly then the various details will be in their exact and
proper size.
At D on Sheet 1 are given two cross sections of sprocket wheels showing side or
flank view of one of the teeth which of course require to be bevelled or curved off at
the top. The letters pc of Figs. B, D, & F and also in Sheet 2 refer to what I call
the "inner pitch circle" or that circle which will just touch all the driving rollers ?*
if the chain is wound tight upon the wheel. It therefore is the limit of the depth of
the gaps between the teeth and a very important datum in the wheel cutting. As
will be seen from D the teeth are all cut into the substance of a disc with parallel
faces, the shoulders s if any, being kept well below the bottoms of the teeth quite out
of the way of the chain side plates. The inner pitch circle should be marked to its
proper diameter upon the face of the disc or blank by means of a pointed tool while
the wheel is in the lathe. Then in cutting out the gaps between the teeth, the
inuer pitch circle forms the limit to which the cutter should be allowed to pene-
trate, while a guage or templet like G, Sheet 2 serves as a check upon the
width and form of the cut. The leg of the guage will just rest upon the inner
pitch circle or tooth bottom at the other side of one of the two teeth to be
guaged, if the gap between the teeth is of the proper tilt as well as form. Should
the step between each pair of teeth present any difficulty in cutting then the
bottom of the gap may be made a straight slope, as shown by a dotted line at y,
Sheet 1, B, and of course such a straight slope may be still more easily adopted
in the case of larger numbers of teeth. Each wheel or tooth diagram on either
Sheet or Sheet 2 has the number of teeth carried by the whole wheel marked
immediately below it. It will most likely be found that one guage like G will
answer accurately enough for a series of several wheels whose numbers of teeth
are in regularly increasing numbers.
I will now give a table of the exact diameters of the inner pitch circles (p c) for
the various numbers of teeth likely to be required in practice. These diameters are
calculated from the formula

page_text: I now add a table of those dimensions of the parts of the
difficult to ascertain exactly from the drawings.
Thickness of the side plates
Distance between insides of side plates of narrow links
ditto of broad links
-
ditto of 2nd form of chain
-
-
ditto ditto where side plates are forked out
Length between shoulders of ferrules and roller pins of
narrow links or links of 2nd form of chain
Length between shoulders of rivets of broad links or
forked ends of links of 2nd form of chain
Length over all of ferrules of narrow links or links of
2nd form of chain
-
Diameters of ferrules and driving rollers
Inside diameters of ferrules and driving rollers
Lengths of driving rollers of narrow links or links of
2nd form of chain and of wire rollers therein -
Lengths of driving rollers in broad links and wire rollers
therein
-
-
-
-
Lengths of wire rollers in joints of chain
Diameter of wire rollers
Diameter of all rivets
-
-
Diameters of shouldered down ends of all rivets
Ditto of all ferrules
The wire anti-friction rollers should all be properly harde
and true and of constant guage and 12 of them should be
each driving roller of the chain.
It is strongly recommended that an even number of tee
the small sprocket wheel, either 8 or 10.
After all ferrules have been fixed into the side plates it
brooch or reamer should be passed through them to cut
time finish the interior to the correct guage and the sa
driving rollers after they have been cut to correct length.
chain can be varied without affecting the principle of const
The wire anti-friction rollers should all be properly hardened and finished straight
and true and of constant guage and 12 of them should be placed in each joint and
each driving roller of the chain.
It is strongly recommended that an even number of teeth should be selected for
the small sprocket wheel, either 8 or 10.
After all ferrules have been fixed into the side plates its necessary that a master
brooch or reamer should be passed through them to cut away all burr and at same
time finish the interior to the correct guage and the same should be done to the
driving rollers after they have been cut to correct length. Of course the pitch of this
chain can be varied without affecting the principle of construction and the width and

page_text: thickness of the side plates or width of the chain itself can be modified to suit any
varying requirements to which the chain may be put. It is of course particularly
applicable to tricycles also.
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. A gear chain for bicycles and tricycles with its appropriate form of sprocket wheel,
the chain being composed of any desired number of similar or alternately similar links,
each and every link carrying an anti-friction cylindrical and hollow driving roller of
about the same outside diameter and calibre as the ferrules of the chain joints and
mounted upon a set of hard wire roller bearings disposed round a rivet joining and
fixed in the two side plates of the link half way and in a straight line between the
centres of the two adjacent chain joints or ferrules; which anti-friction driving rollers
bed themselves behind the teeth of the rear sprocket wheel and transmit power
thereto and bed themselves in front of the teeth of the crank sprocket wheel and
receive the thrust therefrom, and are the only parts of the chain which, in forward
driving, are allowed to come into working contact with the flanks and bottoms of the
sprocket wheel teeth which, owing to the driving rollers falling more or less nearer to
the centres of the sprocket wheels than do the chain joints, a form of tooth is attained,
such that its flank which receives or gives the thrust in forward driving is either
undercut or at any rate cut deeper and more perpendicularly than the opposite flank
or the flanks of the teeth of the usual form of sprocket wheels, thereby strengthening
the teeth as well as obviating any wedging off reaction between chain and sprocket
wheel.
2. The combination of parts forming the links of a gear chain for bicycles and
tricycles substantially as illustrated in Figs. 1A, 1B, and 1° Sheet 1 and herein
described.
3. The combination of parts forming a link or the links of a gear chain for
bicycles and tricycles substantially as illustrated in Figs. 2A, 2B and 2 Sheet 1 and
herein described.
4. Sprocket wheels for bicycles and tricycles having teeth substantially as herein
described and illustrated for use in conjunction with the forms of chains substantially
as herein described and illustrated.
Dated this 25th day of November 1909