Year: 1887

page_text: I, SYDNEY PITT of Sutton in the County of Surrey, Gentleman, 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 my invention is to produce a spring of uniform resiliency throughout
its length so far as possible, and to decrease the weight of metal in the construction of
a spring of a given force. The invention consists in a method of increasing the
resiliency of the plates on the ordinary eliptic spring, and in a method of increasing
the resiliency of such improved eliptic spring by adding thereto an intermediate spiral
spring, or its equivalent, as will be hereafter more fully explained.
I have discovered, in the first place, that the resiliency of a leaf of an eliptic spring
may be very greatly increased by forming the same into what I call a double OG shape,
that is, a shape in which the section of the spring represents three alternately reversed
curves. By building up my spring of such leaves, I both increase the resisting force
of the spring, and distribute its elasticity more uniformly throughout the entire length.
The structure likewise occasions a more uniform and interlocking of the leaves
throughout their lengths, which is advantageous in the resulting structure.
I likewise reinforce my improved eliptic spring by a second spring tending to draw
together the exterior ends of the leaves. This structure will be readily understood

page_text: from the accompanying drawings, in which Figure 1 represents a view of my improved
spring without the intermediate auxiliary spring.
Figure 2 a view of my completed spring with the auxiliary spring attached.
Figure 3 a view of a single leaf of my improved spring.
Figure a cross section of the same.
Figure 5 a view of the method of connecting the ends of the longer eliptic leaves,
In my drawing similar letters refer to similar parts.
A represents generally the leaves of my improved eliptic spring, which as shown,
are held together at their centres by clamps B. The leaves of these springs are of the
shape shown clearly in Figures 3 and 4, forming generally three alternately reversed
curves, which I prefer to be curves of equal diameter, though this is not essential. When
these leaves are laid one upon the other, they will interlock and make a spring the
structure of which ensures great firmness; the principal object however, is to ensure
a greater resisting force than is the case in a flat spring. The external ends of the
single leaves may be attached together in any well known way in the form of spring
without the intermediate auxiliary spiral spring. In that form of spring, however,
I prefer the form shewn in the drawings.
F represents an intermediate spiral spring adapted to be compressed by the move-
ment of the tension rods CC, which rods are provided at their inner ends with off
sets G, or similar contrivances, to bear against the ends of the spiral spring F. The
external threaded ends of the tension rods CCare provided with nuts E, which nuts
are preferably concave on their inner surfaces, as shown in Figure 5. The tension rods
pass through slots in the ends of the eliptic leaves A A which slots are preferably
vertically extended so as to allow freedom of motion without cramping the ends of the
tension rods, which otherwise are liable to be cut off. The nuts E permit of the proper
adjustment of the tension of the spiral spring F, and when adjusted, their inner
concave form prevents their turning and serves the purpose of a lock nut there.
Instead of the spiral spring F, I may use other forms of spring, but I prefer a com-
pression spiral spring in that position. By reason of the combination of the corrugated
eliptic spring with the internal spiral spring, 1 both secure greater resisting force in
the eliptic spring, and also greater longitudinal rigidity in the leaves, which is
important in the operation of the spring, with a corresponding decrease of weight.
The operation is as follows:-Pressure applied in the ordinary way to the leaves
of the eliptic spring, tends both to straighten those leaves and also by reason of the
separation of the ends to compress the auxiliary spiral spring.
I am aware that leaves of eliptic springs have been constructed of sections other
than planes, but such forms have invariably proved unsatisfactory. By reason of the
peculiar shape here shown, I obtain the greatest possible resisting force combined with
uniform elasticity, and, at the same time, a greater longitudinal rigidity. I do not
limit myself to the particular method of holding the leaves of the spring together by
clamps, nor to the particular method of attaching the ends of the spring together.
Though I prefer to have all the leaves of the spring corrugated as described, yet my
invention may be partly utilized by corrugating only one or more of the said leaves.
It is obvious that the peculiar longitudinal corrugations of my eliptic spring act in
combination with the intermediate spiral spring by increasing the longitudinal rigidity
of the leaves of the eliptic spring.
Having now particularly described and ascertained the nature of my said invention
and in what manner the same is to be performed I declare that what I claim is :-
1. The combination of the parts A A of an eliptic spring having hooked ends and
oblong slots therein, nuts E, tension rods C, and spring F, substantially as described.
2. The combination of leaves A A of an eliptic spring having booked ends and
oblong slots therein, with tension rods CC, spring F, and nuts E, having concave
inner surfaces, substantially as described.
3. The combination of an eliptic spring a leaf or leaves of which is composed of a
plate or plates longitudinally corrugated in the form of three reversed curves wih an

page_text: auxiliary longitudinally expanding spring connected to the united ends of the upper
and lower parts of the eliptic spring by means of tension rods, substantially as
described.
4. The combination with the upper and lower parts of an eliptic spring a leaf or
leaves of which is composed of a plate or plates longitudinally corrugated through-
out their length in the form of three reversed curves, of a spiral spring connected by
two tension rods to the points of union of the upper and lower parts of the eliptic
spring, said rods overlapping each other at their inner ends and each passing centrally
through the spiral spring substantially as described.
CARPMAEL & Co.,
Agents for the Applicant.