Improvements in Sprocket Chains and Sprocket Wheels for Bicycles.
Year: 1898

page_text: Date of Application, 23rd Nov., 1898-Accepted, 23rd Dec., 1898
COMPLETE SPECIFICATION.
Improvements in Sprocket Chains and Sprocket Wheels for Bicycles.
I, HAZEN WILLIARD BRADLEY, of the Village of Ilion, in the County of Her-
kimer, and State of New York, U.S.A., Superintendent, 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 object of this invention is to provide a chain that can be economically,
manufactured, and can be made of such material and of such form as to greatly
increase its tensile strength as compared with sprocket chains of ordinary
construction.
In a sprocket chain of the ordinary form of construction, the central or middle
link has usually, heretofore, been made of stock rolled to form and cut off in
sections suitable for the link. In chains constructed in this manner, the strain
on the material on the rolled link is at right angles to the grain of the metal,
and consequently, in the plane of its weakest section. By constructing all the
links of the chain of sheet steel in which the strain is in the same direction as the
grain of the metal, a much stronger link can be produced with the same amount
of material. A farther object of my invention is to provide a sprocket chain and
sprocket wheel adapted for use there-with which will produce a smooth and
steady running chain, free from side sway and substantially free from vibration.
Referring to the drawings forming a part hereof, Fig. 1 shows a side elevation
of a sprocket wheel or pinion, in connection with a portion of my improved chain.
Fig. 2 is a side view of a portion of the chain.
Fig. 3 is a plan view of a portion of the chain.
Fig. 4 shows a cross-section of the chain and sprocket wheel taken on line A-B
of Fig. 1.
Fig. 5 shows an edge view of the sprocket wheel.
Fig. 6 shows a cross-section (except rivet) of one side of the sprocket wheel, and
the chain thereon, said section being taken on line C—D of Fig. 1.
Fig. 7 shows a similar cross-section of a modified form of construction.
Fig. 8 shows a cross-section of the chain taken on line E-F of Fig. 3, excepting
the rivet which is shown in full.
Fig. 9 shows a cross-section of a modified form of construction of chain, taken
on line G H of Fig. 11, except the rivet which is shown in full.
Fig. 10 shows a similar cross-section of another modified form of chain.
Fig. 11 shows a plan of a portion of chain of the form of construction shown
in Fig. 9.
Fig. 12 shows a side view of the same.
Referring to the reference letters and characters in a more particular descrip-
tion of the device, 1 indicates the sprocket wheel which, as shown, is about double
the size of a sprocket pinion which would be used on the ordinary driving wheel

page_text: of an ordinary bicycle; 2 indicates the chain which is shown proportionately large.
The wheel is provided with the peripherial groove 3 which divides each of the
sprocket teeth 4 into two parts, and the groove 3 extends to a point below the
base of the sprocket teeth, as indicated by the dotted line 5.
The chain consists of a train of flat, middle links 6 adapted to be received in
the groove 3 of the sprocket wheel and pairs of flat side driving links 7, 7, con-
necting the links 6. The middle or centre links 6, as well as the side links, are
provided with circular head-like ends with reduced connecting portions, and the
side and middle links are preferably made of substantially the same thickness of
material, and preferably by punching or die cutting out of rolled-sheet metal with
the length of the link lying in the same direction as the grain of the material.
In the substantially central openings in the ends of the middle links are
rigidly secured transverse pins or rivets 8 held against rotation or turning in the
links. On the oppositely-projecting portions of the pins or rivets 8, are engaged
the ends of the side links 7, each pair in a manner which will permit them to
turn freely on the rivet. The rivet opening in the link 7 is also preferably sub-
stantially central with the circular head-like end, and the side links may be
secured by slightly heading the ends of the rivets, as shown.
In the form of construction of chain, as shown in Figs. 1, 2, 3, 4, 6 and 8, the
head-like ends of the links 6 are of larger diameter than the meeting ends of the
links 7. This permits the use of thinner material in the middle links without
reducing the tensile strength of the chain, and provides for other features which
will hereafter appear. The peripherial groove 3 of the sprocket wheel receives
and holds the links 6 laterally, and by extending below the base of the sprocket
teeth, permits the use of the enlarged heads of the middle links without inter-
fering with the proper travel of the chain, and the chain is better held against
side-wise sway. In the constructions as shown in the several figures, the depth
of the groove 3 is sufficient to receive the enlarged ends of the middle links with
the heads of the links coming to a bearing in the bottom of the groove. The
chain is supported, however, in the main by the side links 7 resting on the wheel
at 1.
It will be noted that the opposite parts of the divided sprocket teeth 4 engage
simultaneously on the ends of the pairs of side links 7, instead of against the
single end of a middle link, as in the ordinary chain and sprocket wheel. This,
with the other features, is of importance in that a steadier running chain than
ordinary is provided, and one in which the side sway and vibration are reduced
to a minimum, and the bearings as between the sprocket and chain are com-
paratively large and outside and self-freeing, and a chain of minimum weight of
material can be effectually employed.
In the form of construction of chain shown in Figs. 7, 9, 11 and 12, the diameter
of the heads of the links are proportionately reduced with reference to the
heads of the side driving links 7 of this construction. This reduction in
diameter ought to be accompanied by an increase of the thickness of the material
of which the links are formed. When this chain is used there is a clearance
afforded between the heads of the middle links and the bottom of the groove, as
shown at in Fig. 7. In this form or arrangement the chain is supported entirely
by the side links 7" resting on the wheel at the points marked 1". The same
result may be attained when using the other chain, by making the groove extend
still farther below the base of the sprocket teeth.
In Fig. 10 is shown a shouldered rivet 10 having an enlarged middle portion
adpated to be received in the middle link, and reduced end portions adapted to
receive the side links. This rivet may or may not be rigidly secured against
turning in the middle link. In case it was secured this enlargement enables it
to be secured more firmly, and in case it is permitted to be loose and form a
bearing, it tends to equalize the bearing surfaces as between the middle and side
links.

page_text: Having now particularly described and ascertained the nature of this inven-
tion, and in what manner the same is to be performed, I declare that what
I claim is;
First. The combination of a sprocket wheel having a groove of extending to
a line below the base of the sprocket teeth, and a chain consisting of a set of
middle links and side links having heads of lesser diameter, substantially as set
forth.
Second. The combination of a sprocket wheel having a groove of substantially
the same width extending from the ends of the sprocket teeth to a line below their
base, and a chain having a train of middle, flat links running in said groove,
with alternate pairs of side driving links engaging on their ends directly with
the sprocket teeth.
Third. The combination of a sprocket wheel having a peripherial groove dividing
each sprocket tooth, and a chain consisting of a train of flat, middle links fitting
and running in said groove, and alternate pairs of side driving links having
rounded ends engaging directly with the sprocket teeth.
Dated this 23rd day of November 1898
HAZEN WILLIARD BRADLEY,
By Herbert Haddan & Co.,
Agents for Applicant, 18, Buckingham Street, Strand, W.C., London.