Improvements in Revolving Chain Covers and particularly adapted for Cycles. Gear Cases
Year: 1898

page_text: Date of Application, 10th Oct., 1898-Accepted, 23rd Dec., 1898
COMPLETE SPECIFICATION.
Improvements in Revolving Chain Covers and
particularly adapted for Cycles.
Gear Cases,
I, WILLIAM EDMOND GILBERT, of Leonard Street and Broadway, New York,
in the County and State of New York, United States of America, Merchant, 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:
My present invention relates to revolving chain covers and gear cases
particularly designed for use with driving chains and sprocket wheels of cycles
but which may be used in other relations and upon other machines or devices.
One object of my invention is to produce a chain cover and gear case of flexible
and elastic material which may slightly stretch over the chain and sprocket wheel
so as to exert just sufficient frictional contact with the chain to revolve therewith
around the sprocket wheels.
Another object is to produce a device of this character which will be light in
weight and inexpensive to manufacture, which will envelope the upper and lower
lines of the chain between the sprocket wheels, and which will close tightly at the
edges to keep dust and dirt out of the chain without the use of clips or clasps to
pinch the edges together.
In its broadest aspect my invention contemplates a chain cover and gear
casing having hollow tubes upon its outer edges said tubes being filled with
air or some fluid or liquid either under pressure or at normal pressure, or said tubes
may have a spiral spring imbedded therein for a purpose to be hereinafter
described.
With such a chain cover and gear case applied to a chain and sprocket wheels
of a cycle, the tubes in running around the sprockets are compressed at the
sprocket wheel and the air, fluid or liquid is thus forced by pressure into the
tubes at the upper and lower lines of the chain between the sprockets thus
closing the tubes together at those points with a gentle and elastic pressure
to exclude dust and dirt but to yield sufficiently to prevent abrasion or "running
in" at the points where the sprocket teeth enter between the tubes.
I have also devised simple and efficient means for connecting the ends of the
cover, said means permitting the cover to be cut off or shortened to fit the varying
lengths of chains and sprocket wheels without affecting the fastenings or requiring
re-adjustment thereof.
I attain these objects and advantages by means of the construction shown in
the accompanying drawing which forms part of this specification and in
which
Fig. 1 is a side view of the sprocket wheels and contiguous parts of a cycle
gearing showing my chain cover and gear case applied to the chain and sprockets,
said cover being broken away at a portion of the upper line of the chain to show the
position which the chain assumes within the cover.
Fig. 2 is a plan view of my chain cover prior to its attachment to the chain and
sprockets and prior to the ends being fastened together, and showing the cover

page_text: broken away in the centre to illustrate the manner in which a spiral spring may
be enclosed within the tubes if desired.
Fig. 3 shows a vertical section of one line of the chain having the cover stretched
over it and the edge tubes in contact with each other.
Fig. 4 is a cross section through the cover and edge tubes before being stretched
over the chain and sprocket.
Like letters refer to like parts wherever they occur in the various figures of the
drawing.
Referring to Fig. 1, A is the large or main sprocket wheel, and B the rear or
small sprocket wheel of an ordinary or well known bicycle. C is the horizontal
tube extending from one sprocket wheel to the other. D is the drive chain which
passes over the sprocket wheels in the usual manner.
E is my improved chain cover and gear case which as shown in Figs. 2 and 4
consists of a rubber band a, of proper thickness and elasticity. Upon the outer
edges of this band a, are tubes b, which may be either moulded or subsequently
united thereto.
For some purposes I may find it desirable to inclose or imbed within these tubes
from end to end a spiral spring c, said spring being made of either wire or similar
resilient material of the desired gauge or strength to prevent the tubes from
collapsing too easily. At one end of the band a, a projecting tab d, is provided
and secured to one surface of this tab is a layer or piece of textile fabric e, secured
thereto by cement or similar means. The end of the tubes b, at the sides of the
tab are reduced in size as at f, and said reduced ends may be covered with
inelastic textile fabric.
When it is desired to secure my cover in position upon a chain and sprocket
wheel the desired length of cover is first determined and if the cover is longer
than is necessary, the left haud end as shown in Fig. 2 may be cut off the required
distance to precisely fit the chain to the cover.
It will be understood of course that
the cover as shown in Fig. 2 will be made of a length greater than is required for
ordinary use or as long as the longest chain and largest sprocket wheels will
require and hence may be shortened for shorter chains and smaller sprockets to suit
the convenience of the purchaser. When cut the desired length, cement is applied
to the tab d, and to the reduced ends f, of the tubes and after the cover has been
applied to the chain and sprockets, or rather after the cover has been passed behind
the fork tube g, Fig. 1 the tab d, is cemented to the opposite end of the band
and the reduced ends f, are inserted within the opposite ends of the tubes and the
cement or other adhesive is permitted to dry and set to hold the ends together.
The fabric e, and the fabric surrounding the reduced portions or nipples ƒ, being
inelastic will not permit the ends when united to be separated by stretching the
cover over the chain.
When the cover is revolving with the chain and sprockets, the tubes b, where
they pass over the sprockets are somewhat compressed and this compression causes
a corresponding inflation of the tubes between the sprocket wheels and thus the
tubes are forced together to cover the chain and entirely envelope it.
Upon referring to Fig. 3, it will be seen that the band, at its edges where it is
united to the tubes or moulded therewith is slighty enlarged as at h, and this rib or
reinforce serves to sustain the air, fluid, liquid or spiral spring c, against outward
pressure and thus insure contact of the inner surfaces of the tubes immediately after
passing out of contact with the sprocket wheel.
I may find it desirable for use with certain kinds of cycles to apply a plow or
opener at the lower lines of the chain just in front of the rear or small sprocket
wheel, but for nearly all of the wheels in common use this device is not found
necessary or desirable.
It will be understood that the tubes b, may contain air under ordinary
atmospheric pressure or they may be inflated by means of a pneumatic inflater or
pump or they may contain liquid, fluid or a spring.

page_text: It will be understood that the cover in its normal condition before being stretched
upon the chain is somewhat wider between the tubes, and the tubes b, are somewhat
larger than when applied to the chain and sprocket wheel and this difference in
condition makes the cover assume the position shown in Fig. 1 and 3.
I do not desire to be limited to the exact construction shown as I am aware that
many changes may be made without departing from the spirit and scope of my
invention.
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 revolving chain cover and gear case consisting of an elastic band having
an elastic tube attached at each edge thereof for the purpose described.
2. A chain cover comprising a band of elastic and flexible material having
pneumatic tubes at its edges and fastening means at its ends.
3. A cover for cycle chains consisting of a flat rubber band, pneumatic edge
tubes and fastening means for its ends, said fastening means consisting of end
nipples on the tubes and a projecting tab on the band, substantially as
described.
4. An elastic and flexible chain cover provided with tubular edges and one plain
end, the opposite end of the band having a tab covered with fabric, the tubes being
reduced in size at the sides of the tab to form nipples and covered with textile
fabric, said nipples to be cemented into the opposite ends of the tubes and the tab
to be united to the opposite end of the band, substantially as described.
5. A chain cover comprising a plain flat elastic band reinforced with tubular
edges and fastening means at its ends, said cover designed to be stretched over the
chain to revolve therewith over the sprockets, substantially as described.
Dated this 10th day of October 1898.
BOULT & WADE,
Agents for the Applicant.