Year: 1886

page_text: I ALFRED JULIUS BOULT of 323 High Holborn, in the County of Middlesex,
Engineer do hereby declare the nature of invention (a communication from
John Belmer Armstrong of Guelph, in the County of Wellington in the Province
of Ontario, Canada) 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 the invention is to obtain a carriage or buggy spring which shall
combine the lightness, strength, quick action and symmetry of a single plate spring
with the carrying capacity of an ordinary laminated spring possessing a greater
range of carrying capacity, but obviating the defects of both; and it consists
essentially in a spring composed of two or more plates or leaves, the main-plate
being tapered in thickness towards the eyes from a point at or near each end
of the adjacent or auxiliary plate substantially as hereinafter more particularly
explained.
Figure 1 is an elevation of an elliptic spring embodying this invention.
Figure 2 is an elevation of a semi-elliptic spring.
}
Figure 3 is an elevation illustrating compensating position an elliptic spring
assumes when under heavy pressure.
Figure 4 is an elevation illustrating half of a semi-elliptic spring embodying this
invention.
.
Figure 5 is an enlarged detail cross-section showing how the leaves or plates may
be connected.
Figure 6 represents an ordinary single-plate spring and Figure 7 is a side view
of an ordinary laminated spring.
Figures 6 and 7 being introduced for the purpose of comparison in order that the
nature of this invention may be more readily understood.
Like letters refer to like parts wherever they occur.
;
Heretofore in the construction of elliptic semi elliptic and analagous laminated
springs it has been the common practice to combine three four five or more plates
or leaves in order to obtain the desired supporting capacity and the main plates of
said laminated springs have been of uniform thickness throughout the entire length
[Price 8d1

page_text: between the eyes. To illustrate a laminated spring to carry say (eight hundred)
pounds would be about 40 inches long and composed of four or five plates two
inches wide and from one quarter to five-sixteenths of an inch thick (see Figure 7).
The result of this shape and thickness of the main plate is that in several
inches of the spring close to the eyes there is very little, if any, elasticity which is
so much stock and length of spring wasted and has to be provided for in that
much extra weight of spring between those points, as the rigid part near the eyes
acts as so much leverage on the centre making or causing the elasticity to be
towards the centre, thus losing the elasticity of the ends.
In such a construction there exists objectionable features, first the slow action of
the spring owing to the loss of elasticity near the ends and the undue friction
between the numerous plates, second, if made to carry a heavy load it is too rigid
when called upon to sustain a light one, or vice versa; and third increased cost of
manufacture and increased weight of gear with loss of symmetry or light and
graceful appearance.
In order to overcome the slowness of action of the spring the excess of metal
incident to the rigidity of the main plate near the eyes and the number of leaves
or plates required as well as to obtain graceful appearance and lightness of the gear
a single-plate spring has been employed formed from a plate baving a maximum
thickness of say from one half-inch to nine sixteenths of an inch and tapering to
about one eighth of an inch in thickness at the eyes (see Figure 6). This has
been found to answer well for all purposes of a light gear and will support if the
plate is two inches wide and about forty inches long eight hundred pounds or the
equivalent of four or five plates of ordinary construction in a laminated spring of
the same width and length.
But where the load is to be greater, I have found that the thickness of the
single-plate spring of the construction last referred to, cannot be proportionately
increased without rendering the stock liable to overstrain and the consequent
injury or destruction of the spring.
The object therefore of the present invention is to obtain a spring which shall
combine the lightness strength quick action and symmetry of the one with the
carrying capacity of the other, and possess a greater range of carrying capacity
than either of the constructions hereinbefore recited.
To this end it consists broadly stated in a spring composed of two or more plates
or leaves the main plate being tapered in thickness towards the eyes or from a
point at or near each end of the adjacent plate.
In Figure 3 the compensating position assumed by an elliptic spring of this
make under a heavy load or in a downward surge, is shewn, their cyma-reversa
shape and taper of the main-plate causing the jar received to be gradually
expended before reaching the load carried without causing that unpleasant jar and
reaction experienced in the other makes of springs described.
There are other and minor features which will hereinafter more fully appear.
I will now proceed to describe this invention so that others skilled in the art to
which it appertains may apply the same.
In the drawings a indicates the main-plate and 6 the auxiliary plate or leaf.
The maximum thickness of the main-plate a as at x will be considerably less than
it would otherwise be made if intended to support the load by a single-plate
spring. For instance if in a single-plate spring the greatest thickness would have
been from one half-inch to five-eights of an inch for the load to be supported, I
now employ a main-plate a of say seven-sixteenths of an inch maximum thickness
and an auxiliary plate b of like or less thickness. The auxiliary plate b need not
be half or more than half the length of the main plate a and should be tapered
down at each end to meet the beginning of the taper on the main plate.
The main plate a tapers from the ends of the auxiliary plate 6 to the eyes or
ends of the said main plate at which points the thickness may be reduced to
one-eighth of an inch more or less according to the weight of gear.

page_text: In general terms the main plate a may be said to taper one-half of the distance
between the centre (or supporting point) and ends, more or less, and the auxiliary
plate b should be tapered in the same proportion.
Figure 5 shows the method of connecting spring plates together as follows:-
In forming the hole in the plate a the metal is forced or swaged up into the
annular boss d d the same fitting into a corresponding recess in the plate 6 also
provided with a similar annular projecting boss e and the plates held in position
by the bolt C. By this peculiar union the full strength of the plates is retained
without being weakened by the bolt holes.
A spring constructed in accordance with the principles herein before specified
will have the following advantages; viz:-lightness and graceful appearance
saving of stock, quick and uniform action and the stock will not be be liable to be
overstrained, advantages with the exception of the last incident to the single-plate
tapering spring, while it will possess all the sustaining or supporting power
incident to the laminated spring in ordinary use, and this with a greater saving in
weight or stock as well as in general appearance. Further the quick action of the
spring near its extremities takes the jar off the body and the friction of the
auxiliary plate on the main plate while it is not sufficient to reduce the spring
action unduly, still is enough to serve as a support and as a brake in the too-rapid
reaction of the spring under heavy loads and in these respects the present invention
differs from both forms of springs hereinbefore referred to.
A tapered main plate of seven-sixteenths maximum thickness tapering to the
thickness of one eighth of an inch with an auxiliary plate as hereinbefore described
will support as heavy a load as five quarter inch plate of the old construction of
that shown in Figure 7 of the drawings.
Having now particularly described and ascertained the nature of the said
invention as communicated to me by my foreign correspondent and in what
manner the same is to be performed, I declare that what I claim is :-
1. A buggy or carriage spring composed of two or more plates or leaves the
main plate being tapered in thickness from a point at or near each end of the
auxiliary or adjacent plate, substantially as and for the purpose specified.
2. A buggy or carriage spring composed of a main and an auxiliary plate, both
of said plates being tapered in thickness for one-half more or less of the distance
between the centre (or supporting point) and ends of said plates, substantially as
and for the purpose specified.
3. In a buggy or carriage spring connecting the main and superposed plates by
annular bosses fitting into suitable recesses and held in position by a bolt or rivet
substantially as and for the purpose specified.
4. An elliptic buggy or carriage spring composed of two or more plates, the
main plate being tapered and formed in a cyma reversa or O. G. shape substantially
operating as and for the purpose specified and described.
Dated this fith day of September 1886