IMPROVE-. MENTS IN SPIRAL SPRINGS FOR RAILWAY CARS AND CARRIAGES, AND OTHER PURPOSES
Year: 1878

page_text: LETTERS PATENT to George Edward Gray, of San Francisco, State of California,
one of the United States of America, C.E., for the Invention of "IMPROVE-.
MENTS IN SPIRAL SPRINGS FOR RAILWAY CARS AND CARRIAGES, AND OTHER
PURPOSES."
Sealed the 30th August 1878, and dated the 23rd April 1878.
COMPLETE SPECIFICATION filed by the said George Edward Gray at the
Office of the Commissioners of Patents on the 23rd April 1878.
GEORGE EDWARD GRAY, of San Francisco, State of California, one of the United
States of America, C.E. "IMPROVEMENTS IN SPIRAL SPRINGS FOR RAILWAY CARS
AND CARRIAGES, AND OTHER PURPOSES."
In the accompanying Drawing (reference being had thereto),-
Figure 1 is a perspective view of my improved spring when at rest, and a
sectional view of the bed plate used therewith.
Figure 2 is a sectional elevation of the spring when it is in a state of partial
compression.
Figure 3 is a similar view of the spring when it is still further compressed,
showing its action under a heavy load.
The object of my Invention is to produce a spring which is nearly equally elastic
under light or heavy loads, and which does not allow the load to impinge with a
shock when the ordinary bearing power of the spring is overtaxed. This is
accomplished by constructing the spring in such manner that an extraordinary and
supplementary elasticity possessed by the spring is called into play as the weight
increases and the ordinary elasticity is exhausted or nearly so.
To this end my Invention consists in forming a spiral spring of conoidal shape
from any suitable material, having such cross section that the coils when compressed
together will slide upon and into each other on inclined surfaces, the outer surface
of one coil pressing against the inner surface of the other next below it, and acting
to throw it outwards as the weight of the load increases. The coils thus enlarge
their diameters until each coil is compressed within the next larger one. This

page_text: action is facilitated by the use of a bed plate of conoidal shape, upon which the
spring is placed to assist in the expansion of the larger coils, and this part of my
Invention may be used with the spring to increase its lateral elastic power or
resilience when desired.
In the Drawing, Figure 1 represents a spiral spring made in accordance with the
principles of my Invention. Its form is that of a conoid with the spirals increasing
in regular manner, and of such diameters that the under face of one coil is over
and in line with the upper inner face of the next larger coil below it. Thus when
compression takes place the coils are brought in contact and slide upon and into
each other with an expansive action. The wire or metal of which this spring is
constructed is shown as having a cross section a, a, b, b*, of rectangular shape,
but other angular shapes as well as curved or round shapes may be employed as the
same lateral expansion of the spring, constructed from material of any of such
shapes can be produced by forming the spring after the manner above described;
that is to say, with the spirals increasing in such regular manner, one beneath the
other, that the outer face of one coil shall be over and in line with the inner face of
the next larger coil beneath it when the spring is at rest or but lightly loaded.
A spring constructed of such conoidal form has the pitch of the several spirals
constantly increasing as the diameters of the spirals decrease, so that the smallest
coils have a greater pitch than the largest one, and this is necessary in order to
bring the outer face of one coil immediately over or in line with the inner face of
the next larger coil below it, that when compression takes place the coils will come
in contact and slide upon and within each other. This spring when heavily loaded
has a supplemental or additional elastic power caused by the lateral expansion of
the coils or the tendency of each coil to return to its normal position from which it
has been forced by the compression of one coil within the other. By such action
they sustain each other, and the spring remains elastic until entire compression may
take place by added weight.
In connection with this spring I use a base or bed plate shown at B in section,
Figure 1 of the Drawing, which can be employed to assist in the expansion of the
larger coils, but the action of the spring is not dependent upon the use of the bed
plate in every case, and it may be used only where an increased size of spring is
employed, and a heavy load is sustained where the resilience of the larger coils of
the spring would be better brought into play.
When this conoidal bed plate is used, the last coil of the spring need not be
tapered off, but in all other cases the bottom as well as the top coil of the spring is
tapered off to form a flat bearing surface.
In the Drawing A, A, represent the coils of the spring; a, b, the faces of the
coils that are in contact and slide upon each other when the spring is compressed;
and B, the conoidal bed plate upon which the last coil of the spring is placed when
an additional action is required. As thus constructed my Invention combines
elasticity with great strength, and requires less material to sustain the same load
than any other form of spring known to me, and it possesses greater elasticity and
sensitiveness to motion even under a heavy load for the sliding action of the coils
and their expansion, when pressed against each other, gives an additional move-
ment beyond the vertical resilient action of the spring.
Having thus fully described my said Invention and the manner of operating the
same, I wish it understood that I claim,-
First. A spiral spring constructed of any suitable material of a conoidal form
with the diameters and pitches of the different coils and the cross section of the
material used of such size and so proportioned to each other that a sliding and
expanding action of the coils upon and within each other takes place when the
spring is compressed, substantially as and for the purpose herein set forth.
Second. In a spiral conoidal spring, the arrangement of the coils one above the
other, in such position that the outer surface of one coil shall be over and in line
with the inner inclined surface of the next larger coil below, whereby, when com-
pression takes place, these two surfaces shall come in contact, and the larger coil

page_text: shall be expanded by the smaller one next above or within it, substantially as
herein described for the purposes set forth.
Third. In combination with the spiral conoidal spring A, constructed substan-
tially as described, the conoidal bed plate B, of the shape and operating as herein
described for the purpose set forth.
In witness whereof, I, the said George Edward Gray, have hereunto set my
hand and seal, this Fifth day of April, in the year of our Lord One thousand
eight hundred and seventy-eight.
GEORGE EDWARD GRAY. (L.S.)