Improvements in Sprocket Chains.
Year: 1896

page_text: Date of Application, 16th Mar., 1896-Accepted, 16th May, 1896
COMPLETE SPECIFICATION.
Improvements in Sprocket Chains.
We, BENJAMIN FRANKLYN SPARR, of No. 3 Centre Street, in the City of
Newark, County of Essex and State of New Jersey, United States of America,
Engineer, and FREDERICK KNAPP PARTRIC, of No. 616 Pavonia Avenue, Jersey
City, in the County of Hudson, and State of New Jersey, United States of America,
Machinist, 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 improvement in chains for connecting sprocket
wheels, commonly formed of a series of central links having their adjacent ends
connected together on opposite sides by the overlapping ends of lateral links
pivoted thereto by pins having their ends flanged or riveted outside of such lateral
links so as to secure such parts permanently together; whereby intermediate spaces
are formed between the extremities of the adjacent central links for the penetration
of the sprocket teeth.
It is the object of our present invention to provide a sprocket chain of which the
pivotal pins may be detached to permit the individual links to be removed from
the chain for renewal when their effectiveness becomes impaired by wear, or in
order that links may be added or removed to lengthen or shorten the chain when it
is required to change the sprocket wheels connected thereby for varying their
relative speeds, as is sometimes desired in bicycles and similar vehicles propelled
by power transmitted by cranks.
This object we attain by employing, in sprocket chains of ordinary construction,
pivotal pins of a length slightly exceeding the combined width of the lapped ends
of the adjacent links, forming in the projecting ends of said pins lateral nicks or
grooves and applying to such nicked or grooved ends of each pair of adjacent pins
thin flat springs notched in one edge at each end to fit the same and overlying the
lateral or outer members of the chain. Such springs are provided with suitable
means, hereinafter described, for retaining them in place.
The invention will be more fully understood by reference to the annexed
drawing, wherein
Fig. 1 is a perspective view of several connected links of a sprocket chain
embodying our improvement, and
Figs. 2 and 3 are transverse sectional views, on line xx and y y in Fig. 1,
respectively;
Fig. 4 is a side view of a slightly modified form of pivotal pin from that shown
in the preceding figures.
Fig. 5 is a side view of a flat locking spring presenting a modification of that
shown in the preceding figures, and Fig. 6 is a transverse sectional view, similar to
Fig. 3, embodying said spring in section.
The chain is formed in the usual manner with a series of central links a connected
together on opposite sides by the overlapping ends of lateral links b by means of
pivotal pins p to form a series of central apertures for the admission and engagement
of the teeth of the sprocket wheels.
The pivotal pins are of a length slightly exceeding the combined thickness of
the links a and b where they overlap so as to afford space on their exposed ends
for the shallow annular peripheral grooves p', as indicated in Fig. 2, or for parallel
Dicks p², as indicated in Fig. 4. Thin flat springs s, preferably conforming with

page_text: the shape of the lateral links as in Fig. 1, having near the ends of one edge the
transverse notches & adapted to fit the contracted portion of said pins formned by
the grooves or nicks, are applied to each pair of adjacent pivotal pins to overly the
lateral links b; whereby said pins are effectively locked in place in their respective
links.
For retaining the springs in place, each link b may be provided intermediate to
its ends with a transverse hole o (countersunk if preferred) and the spring with a
corresponding projection 2 (Fig. 3), by punching or other means, adapted to spring
into and engage said hole o when applied to the pins p; or the notched edge of
said spring may be provided with an inwardly projecting ear for similar
engagement with the corresponding edge of the adjacent link, as in Figs. 5 and 6.
If desired, one end of the pivotal pin p may be permanently flanged into a head p³,
in which case the series of locking springs s would be confined to one side of the
chain, but would operate with equal effectiveness; permitting the pins to be readily
withdrawn by the detachment of the springs from the nicked or grooved opposite
end by springing their central portion outward for the disengagement of the ear or
projection from the adjacent lateral link.
It is obviously immaterial what is the particular form of the spring s, and to what
particular pair of pivotal pins it is applied, it being evident that said springs may
be notched to fit the ends of pins in the ends of adjacent links and made to conform
with the shape of the corresponding central link and provided with an ear s³ of
suitable length to engage the latter.
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that what
we claim is :
1. In a sprocket chain formed of series of links with overlapped ends pivoted
together, the combination, with the pivotal pins for said links having one or both
ends provided with peripheral grooves or nicks as described, of flat springs having
notches in one edge fitted to and adapted to engage the grooves or nicks in each
adjacent pair of said pivotal pins, and means for retaining said springs in engagement
with said pins, as and for the purpose set forth.
2. The sprocket chain formed of a series of central links a, series of lateral links b
with transverse holes o, the pivotal pins p with peripheral grooves p' in the ends,
and the flat springs s with notches & fitted to said grooves in the pins p and formed
with projections & adapted to enter and engage the holes o in the links b
substantially as herein shown and described.
Dated this 16th day of March 1896.
WHEATLEY & MACKENZIE,
40 Chancery Lane, London, W.C., Agents.