IMPROVEMENTS CONNECTED WITH INDIA-" RUBBER SPRINGS FOR USE AS DRAW SPRINGS, BUFFER SPRINGS, AND BEARING SPRINGS, AND ALSO AS SEGMENTS OR SECTIONS OF ELASTIC TYRES FOR CARRIAGE WHEELS AND SIMILAR USES
Year: 1873

page_text: LETTERS PATENT to William Firth, of Rose Villa, Viewforth, Edin-
burgh, for the Invention of "IMPROVEMENTS CONNECTED WITH INDIA-"
RUBBER SPRINGS FOR USE AS DRAW SPRINGS, BUFFER SPRINGS, AND BEARING
SPRINGS, AND ALSO AS SEGMENTS OR SECTIONS OF ELASTIC TYRES FOR CARRIAGE
WHEELS AND SIMILAR USES."
Sealed the 17th October 1873, and dated the 18th June 1873.
PROVISIONAL SPECIFICATION left by the said William Firth at the
Office of the Commissioners of Patents, with his Petition, on the
18th June 1873.
I, WILLIAM FIRTH, of Rose Villa, Viewforth, Edinburgh, do hereby.
declare the nature of the said Invention for "IMPROVEMENTS CONNECTED
WITH INDIA-RUBBER SPRINGS FOR USE AS DRAW SPRINGS, BUFFER SPRINGS, AND
BEARING SPRINGS, AND ALSO AS SEGMENTS OR SECTIONS OF ELASTIC TYRES FOR
CARRIAGE WHEELS AND SIMILAR USES," to be as follows:-
These improvements which constitute my present Invention relate to
the disposition of the india-rubber or elastic parts of such springs with
the iron or metallic parts connected with such springs, so that the load

page_text: or resistance to be borne by the india-rubber shall be divided, and thus
any part of the india-rubber will have to sustain but one-half, one-third,
or one-fourth of the load put upon or resistance required from the
springs, as the case may be. Thus will the durability of the india-rubber
be greatly promoted, and it will be the better enabled to sustain much
greater loads or resistances than heretofore; and generally a less amount
of india-rubber will be required than is employed in the ordinary way
where one piece of rubber has to sustain the entire load or resistance.
-If it
These improvements are carried out in the following manner :-
be desired to halve the load or resistance to be borne by the india-rubber
two iron or other metal boxes are provided, one without ends and the
other without sides, the external length of one being about equal to the
internal length of the other, and any one of them provided with one of
its remaining sides moveable, say its cover.
By means of this moveable and attachable part the one box may be
made to link with the other like two links in a chain, whereof one is a
U link attached by a cross pin. Between the inside top surface of one of
these boxes so linked and the outside top surface of the other I place
one block or piece of india-rubber, and between the outside bottom
surface of the first and the inside bottom surface of the second I place
another block or piece of india-rubber.
The boxes being constructed of suitable strength, if pressure or a load
be placed on the outside top surface of one of them it will be borne up,
one half. by one rubber block and the other half by the other rubber
block.
When these springs are applied to wheels so as to form elastic tyres
therefor a series of boxes or cells, as above described, is formed in the
rigid wheel all round its periphery, and combined with a series of boxes
or cells linked thereto and cushioned therewith in the same manner as a
single pair of boxes or cells as already described. The application of
such springs to the wheels of traction engines admits of the easy appli-
cation therewith of "spuds" or projections, whereby the adhesion of the
wheels is made more effective for soft or frosty roads.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Firth in the Great Scal Patent Office on
the 18th December 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
FIRTH, of Rose Villa, Viewforth, Edinburgh, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eighteenth day of June, in the year of
our Lord One thousand eight hundred and seventy-three, in the thirty-
sixth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said William Firth, Her special licence, [that
I, the said William Firth, my executors, administrators, and assigns,
or such others as I, the said William Firth, my executors, adminis-
trators, and assigns, should at any time agree with, and no others from
time to time and at all times thereafter during the term therein ex-
pressed, should and lawfully might make, usc, exercise, and vend,
within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man, an Invention for "IMPROVEMENTS CONNECTED
WITH INDIA-RUBBER SPRINGS FOR USE AS DRAW SPRINGS, BUFFER SPRINGS, AND
BEARING SPRINGS, AND ALSO AS SEGMENTS OR SECTIONS OF ELASTIC TYRES FOR
CARRIAGE WHEELS AND SIMILAR USES," upon the condition (amongst
others) that I, the said William Firth, my exccutors or administrators;
by an instrument in writing under my, or their, or one of their hands
and scals, should particularly describe and ascertain the nature of the
said Invention, and in what manner the same was to be performed, and
cause the same to be filed in the Great Seal Patent Office within six
calendar months next and immediately after the date of the said Letters
Patent.
:
NOW KNOW YE, that I, the said William Firth, do hereby declare
the nature of my said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement, reference being had to the Drawings hereunto
annexed and to the letters and figures marked thereon (that is to say):-
This Invention relates to a novel disposition of the india-rubber or
clastic parts of that class of springs to which my Invention is confined
with respect to the iron or metallic parts of such springs, the object
being to divide the load to be borne or resistance offered by the india-

page_text: rubber that no component part of a section of the india-rubber taken in
the line of resistance will have to sustain more than one-half, or say
one-third or one-fourth (as the case may be) of the load put upon or
resistance required from that portion of spring. Thus will the durability
of the india-rubber be greatly promoted, and it will be the better
enabled to sustain much greater loads or resistances than heretofore on
any given area to be cushioned, and generally a less amount of india-
rubber will be required than is employed in the ordinary way where one
piece of rubber has to sustain the entire load or resistance.
These improvements may be carried out in the following manner :-
If it be desired to halve the load or resistance to be borne by the india-
rubber two iron or other metal boxes are provided, one without ends and
the other without sides, the external length of one being about equal to
the internal length of the other. One of the boxes is provided with a
removeable piece, say its cover, which admits of the one box being linked
with the other like two links in a chain. Between the inside top surface
of the one box so linked and the outside top surface of the other I place
a block or piece of india-rubber, and between the outside bottom surface
of the first and the inside bottom surface of the second I place another
block or piece of india-rubber.
If thin pressure be placed on the outside top surface of one of the
boxes it will be borne up one half by one rubber block, and the other
half by the other rubber block.
When adapting springs of this construction to wheels so as to consti-
tute clastic tyres therefor a series of linked boxes may be applied to or
cells formed around the periphery of the rigid wheel and combined with
a series of boxes, the same being cushioned like a single pair of boxes.
In the accompanying Drawings Figures 1 and 2 are sectional elevations
of a pair of linked boxes at right angles to each other, and shewing the
application of the Invention to a bearing spring or to a buffer spring.
In these Figures the frame or load w is to be cushioned on the support 8.
u is a rectangular metal box bolted or attached to, or it may be a part of
the frame w. This box is linked with the rectangular box m, which is
bolted or otherwise fastened to the support 8, as shewn in Fig. 2.
Between the top of the box m and the bottom of the boxu a recoil
cushioning picce of india-rubber c is placed, and between the bottom of
the box u and the plates is placed the india-rubber or other compressible

page_text: spring of any suitable shape, and a similar spring is in like manner
placed between the top of the box m and the bottom of the box u, or
directly between the top of the box m and the frame or plate w carrying
the load. The side of the box u placed on the spring r³, and the side of
the box m placed under the spring 72 occupying fixed positions with
respect to the plates w and s, to which they are respectively attached, it
will be evident that one half of the load will be borne by r¹ and the
other half by . By this arrangement a diminution of action on the
surfaces of these springs will result, and their durability will thereby be
promoted, and this will be of decided utility when the load to be borne
is great and the available area for cushioning is small.
Fig. 3 illustrates one mode of applying the same principle of con-
struction of springs for use, as draw springs in situations where the load
to be drawn is great, and where it is an advantage to have the width of
the spring as little as possible, as for instance in a ship's cable, where
the length of spring is on the other hand of little consequence. Herc
the box u is lengthened out and divided into three compartments, and
attached by the one end to the frame or-load w in any convenient way.
Inserted in the box u, which is cast in two halves and joined by flanges
and bolts, is a metal rod m fitted with discs 1, 2, 3, which are screwed
and keyed or otherwise suitably attached thereto. These discs are
received each in its own compartment as shewn, and they perform
together the same function as the parts marked m in Figures 1 and 2.
Between the discs and the divisions in the box u blocks of rubber 71, 72, 7³,
are inserted. Each of these blocks or springs will sustain one-third of
the draw or pull put upon the load w in the direction of the arrow.
t
"
26
Figures 4 and 5 show one mode of applying these springs in a series
to form the clastic tyres of traction engine wheels. In Fig. 4 (a side
view of part of such a wheel) and in Fig. 5 (a cross section on the
radial plane passing through the centre of binding bolt p), the parts
having like uses are marked with the same letters. f. f, are the sides of
the wheel w. To them metal rings u are attached by rivets v or other-
wise, and to both of which the flanged bars 6 (which bars are the
moveable sides of the upper boxes in this case) are also attached by
means of the tie bolts p. The parts w, u, b, and p, thus together form
three sides of a box as marked by w and u in Fig. 1. The outer or
lower boxes m carry in them the rubber springs 2 which bear against
the sides 6 of the upper boxes, and the removeable parts thus serve to
.

page_text: link the boxes m to the wheel. The springs ² are inserted between the
boxes m and the periphery of the wheel w. The rubber pieces J are
side cushioning pieces between the several boxes m, of which there may
be one, or as here shewn three in the width of the wheel. s.are steel
facing pieces rivetted to the boxes m.
Figures 6 and 7 exhibit another form of applying these springs. Here
the covers or tops of the lower boxes m are made the removeable or
linking parts. These tops are marked m', and are attached to the ends
of m by bolts p and nuts n. The bottoms 6 of the upper boxes (w, u, b),
are formed by one continuous hoop 6 surrounding the wheel, and the 1
sides are made with internal lugs (scc Fig. 7) for the purpose of
keeping the hoop 6 from moving sideways. In this arrangement it will
be seen that the hoop 6 holds the tyre to the wheel. Here, if the
bearing blocks be made large and pressed into position, the pieces c
will be compressed, and therefore with the hoop 6 form a friction strap 1
round w, and thus prevent the rigid inner wheel w moving round inside
of the elastic tyre. In this arrangement also it would be easy to provide
for the bearing pieces 71 or 72, or both, being continuous all round the
wheel, when of course the side cushioning pieces marked J¹ would be
absorbed into the pieces 7. When these springs are used in a serios, 2
such as a wheel tyre, a variety of modes of construction may be adopted
in forming the upper and lower or the inner or outer boxes and in
linking them with each other. The variations will arise from peculiaritics
of position, shape, and other circumstances; yet these variations will
only be matters of detail. For example, the upper boxes in Figures 62
and 7 may be replaced by cells or partitions in the rigid inner wheel,
whercof the periphery would then be 6, and such a change would call
for but little if any modification in the construction of the outer
boxes m

page_text: under the above in part recited Letters Patent I claim constructing
springs as above described, whereby the load or direct strain which is to
be borne or resisted by the india-rubber blocks or portions of such
springs is divided up and distributed as and for the purpose herein-before
cxplained.
In witness whereof, I, the said William Firth, have hereunto
set my hand and seal, the Fifteenth day of December, in the
year of our Lord One thousand eight hundred and seventy-
three.
springs is divided
explained.
up and distributed as and for the purpose herein-before
In witness whereof, I, the said William Firth, have hereunto
set my hand and seal, the Fifteenth day of December, in the
year of our Lord One thousand eight hundred and seventy-
three.