IMPROVEMENTS IN LEAF SPRINGS
Year: 1884

page_text: COMPLETE
SPECIFICATION.
I, THOMAS MIDELTON of Sydney in the Colony of New South Wales, Engineer
do hereby declare the nature of my invention for "IMPROVEMENTS IN LEAF
SPRINGS" and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement:-
This invention of improvements in leaf springs relates to the introduction of
rollers between each of the plates or leaves and to the combination with such
roller leaf springs of distance pieces between each plate or leaf at the centre and
holding the whole together by means of a bucklo put on cold and fastened by a
cotter.
The introduction of rollers preferably of steel at the ends of and between each
plate greatly reduces the friction between them and fully developes the elasticity
and useful effect of each plate composing the spring, the liability of breaking being
almost entirely removed. In ordinary springs the leaves touch each other during
their entire length whereas in my case the only points of friction are on the rollers.
The steel rollers referred to are made with heads at each end to prevent any
lateral movement of the spring plates and thus avoid the necessity for making the
usual projection and recess in the ends of the said plates to keep them in their
proper place.
The central strap or buckle for holding the spring plates together I put on cold
and draw the said plates closely and accurately together by means of a cotter
instead of by the usual method of heating the said buckle and then cooling it in
water. The "temper" of the spring plates is not destroyed at the centre by this
method of construction but remains always constant throughout and no matter
what load may be on the spring the buckle is not looseued as in ordinary springs
because the plates are held by a line of contact at the top and the full contact of
the width of the buckle at the bottom.
The elasticity of springs made on this system is always the same whether loaded
or unloaded which is contrary to the usual bearing springs which are practically
solid when loaded.
Referring to my drawings Figure 1 is a bottom plan of one of my springs-
Figure 2 side elevation and Figure 3 top plan of same. Figures 4 and 5 show side
and sectional details of roller and Figures 6 and 7 end elevation and section of
plates. AA are the rollers between the plates or leaves B B. CC are the
distance pieces in the centre-D the buckle and E the cotter.

page_text: Having thus described the nature of my invention and tho manner of performing
same I would have it understood that I do not confine myself to the number of
plates or leaves in my springs nor to the number or precise position of the rollers
between them nor to the materials of which any of the parts may be made but
I prefer the plates and springs to be of steel and to be arranged and constructed in
the manner substantially as herein described and explained and as illustrated in
my drawings. What I believe to be new and only claim as my improvements
in leaf springs is
First. The introduction of rollers between the leaves or plates of such springs.
Second. In combination with such roller-leaf springs placing distance pieces
between each plate or leaf at the centre and fastening the whole together
by means of a buckle put on cold and a cotter substantially as herein described and
explained.
Dated this twentieth day of August One thousand eight hundred and eighty
Witness,
four.
FRED, WALSH.
THOS MIDELTON.