Improvements in Balanced Pistons for Steam Engines.
Year: 1889

page_text: Date of Application, 18th June. 1889-Accepted, 20th July, 1889
COMPLETE SPECIFICATION.
Improvements in Balanced Pistons for Steam Engines.
I, WILLIAM JAMES THOMAS of Saucelito in the county of Marin and state of
California United States of America Machinist do hereby declare the nature of my
Invention for "IMPROVEMENTS IN BALANCED PISTONS FOR STEAM ENGINES" and in
what manner the same is to be performed to be clearly described and ascertained in
and by the following statement :-
My invention has for its object to prevent excessive and uneven wear of the piston
and its cylinder in locomotive engines and other engines of the horizontal type; and
the nature of the said invention consists essentially in balancing the piston or taking
its weight to a certain extent from the bottom or lower side of the cylinder in which
it travels by introducing and maintaining the steam pressure of the cylinder directly
under the piston or between it and the bottom of the cylinder.
I attain the desired end and object and produce my said invention by the-
construction illustrated in the accompanying drawing, in which-
Figure 1 represents in side elevation a horizontally acting piston and portions of
the steam cylinder in which it is arranged to work, the piston being constructed
according to my invention.
Figure 2 is a similar view of the piston but with a portion thereof shown in
section.
Figure 3 is a top view of the piston with the plate or disk that forms the head
thereof taken off to show the steam spaces within.
The same letters of reference are used to denote corresponding parts in the several
figures of the drawing.
In applying my said invention to pistons of the kind most generally used in
"locomotives" of the present day I simply remove that part known as the "Bull-
Ring" or the grooved rim of the piston in which the packing rings are set and in its
place I substitute a ring B having grooves g for two packing rings D D so formed or
disposed that the rings are inclined and stand in opposite positions, converging at the
top or the highest part of the piston rim and from that point standing outward so
that the greatest width of space between the rings is at the bottom or lowest part of
the piston. The grooves g in the piston rim are therefore cut diagonally and in
opposite directions to give the packing rings this oblique position on the piston.
When set in position for work the piston has the wider space E at the point of
greatest divergence of the two rings turned towards the lowermost side of the
cylinder, and at this point the rim or periphery of the piston is cut away or turned
off, as indicated by the dotted lines at the bottom of figure of the drawing, to
form a pocket h, and into this pocket the steam from the cylinder is introduced by
passages g*g* leading through the periphery of the piston into the hollow
inside the piston, and the passage F that connects the pocket h with the piston space I.
The passages g*g* are carried from the bottom of the grooves g, into the hollow
space I, and as the packing ring has always more or less play in its groove there is
sufficient space between the ring and the side of the groove for the live steam to find
its way into the piston and so into the pocket h.
space
By locating these inlets g* in the grooves the packing ring is made to act as a
check valve and keep the body of confined steam inside the piston so that it will not
be drawn out nor the pressure within the pocket affected during the time of exhaust
in the cylinder. If the inlet passage is carried through either end or head of the
piston, however, it will be necessary to apply a check valve in that passage in order to
hold the steam inside the piston and maintain steady pressure thereof in the pocket h
beneath the piston during work.
I
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page_text: By this means, namely, holding and confining the live steam between the piston
and the side of the cylinder I am enabled to balance the piston sufficiently to over-
come the wear of these surfaces traveling on each other in steam cylinders of the
horizontal type.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is―
1. A steam piston for horizontal steam engines having a pocket or space h in the
lower side, a hollow space I within the body of the piston, a connecting passage
between said pocket and hollow space, and passages or apertures within the piston
arranged to carry the steam from the cylinder into the said space, substantially
as described for operation as set forth.
2. A piston for steam engine cylinders having packing-rings set obliquely and
divergently, as described, and the recess formed between them at the part of greatest
divergence in combination with ports or passages, as g* F, which are adapted to
connect the said recess with the steam space of the cylinder outside the piston, as set
forth.
Dated this 18th day of June 1889
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicant.