Door Springs, and Analogous Articles.
Year: 1888

page_text: Door Springs, and Analogous Articles.
I, JAMES BURBRIDGE of the firm of Messrs. W. Warne & Co. of the India Rubber
Works, Tottenham in the County of Middlesex, India Rubber Manufacturers, 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 a novel mode of manufacturing solid india rubber chest
expanders and analogous articles, such as door springs, etc.-A solid rubber chest
expander consists of two handles connected together by a rubber spring, the handles
being attached to loops formed at opposite ends of the rubber spring. In order that
the advantages of my improved mode of manufacture may be clearly understood, it
may be desirable to describe the usual mode of making these chest expanders, which
is as follows:-A solid india rubber cord, of the proper diameter, is cut of sufficient
length to permit of a loop being made at either end.-Each end is scarfed or
bevelled off to a feather edge, and is coated with india rubber solution.-The
bevelled or scarfed ends are then turned over, and pressed firmly down onto
the round body of the cord (which may also have been previously coated with
solution) at such sufficient distance as to form the required loops. A piece of
india rubber coated canvas of a suitable shape is then cemented on the inner part of
the loop, as a stay, and also to protect the eye from the friction of the ring of the
handle. The joints thus formed are weak, as the fine feather edge is liable to become
unfastened, and turn up, and as the joint does not then stretch evenly, the parts
become gradually detached and the joint breaks.
Now by my improved manufacture this inconvenience is avoided, and strength and
elasticity are secured.
In carrying out may invention, as applied to an expander with the strength of half
inch rubber cord, I take a length of unvulcanized india rubber solid cord of about
one inch in diameter, of any section, and I mark off or reserve at each end a portion
of a length equal to each loop or eye when formed.-I next stretch evenly that

page_text: portion of the cord between the two reserved portions until its diameter is reduced
to half an inch. I then make an incision longitudinally in each reserved end, of
a length required to make the opening of the loop, and I open out the incised
portion, in which I cement a canvas stay coated with india rubber.-I then round
off the angles, which can easily be done as the rubber compound is in a plastic state,
and place the cord in a suitable mould to be vulcanized in the usual manner.
stretching of the cord by hand will result in a crude and rough appearance, I prefer
to mould or manipulate it before vulcanization, as well as to vulcanize in a mould
in order to consolidate the rubber compound and give smoothness and uniformity of
strength to the cord.
As the
In the accompanying drawing, I have illustrated the various steps in my improved
mode of manufacturing chest expanders ;-thus, Fig. 1 represents the piece of solid
cord of unvulcanized india rubber compound. Fig. 2 represents the elongated
central portion and the incisions for the loops. Fig. 3 shows the incisions opened out
and the stays in position, and Fig. 4 shows the final form the spring will take before
vulcanization, and which it will retain after vulcanization.
In Fig. 1, the parts in which the loops are to be formed are marked off by dotted
lines A A.-In Fig. 2, B B are the incisions, and in Figs. 3 and 4, CC are the stays.
In Fig. 4, the angular ends shown by dotted lines are rounded off, and all parts
of the spring are moulded or manipulated as before described.
By my improved mode of manufacturing chest expanders, I obtain a jointless
spring of considerable strength.
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
The mode as herein described and shown of manufacturing jointless india rubber
springs for chest expanders and other purposes.
Dated this 19th day of September 1888.