Improvements in Pistons.
Year: 1890

page_text: Date of Application, 11th Oct., 1890-Accepted, 15th Nov., 1890
COMPLETE SPECIFICATION.
Improvements in Pistons.
We, WILLIAM JOWETT of Dove Bank Mills Mellor near Marple-Bridge in the
County of Chester Manufacturer, and GEORGE SPENCER of 66 Bennett Street Hyde
in the County of Chester, Mechanical Engineer, 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:-
This invention relates to pistons and it has for its objects to ensure a close and
accurate fit between the piston and the cylinder, and thus to prevent the passage of
steam or other fluid past the piston, and to reduce the friction between the piston and
the cylinder.
In carrying out our invention we employ two rings (or in the case of a single acting
machine it may be one ring only) transversely divided as in the ordinary well-known
Ramsbottom rings. The two ends of each ring instead of abutting together, are
tapered or inclined so as to form a triangular space having its base at about the
inner diameter of the ring and its apex at the outer diameter where the two ends are
in contact with each other. In the body of the piston block, opposite to the triangular
space in each ring, there is formed a radial cylinder within which there is a ram
having a wedge-shaped head corresponding with the triangular space. Each radial
cylinder has its base in open communication with a face of the piston in such a manner
that one cylinder communicates with one side of the piston and the other cylinder
with the other side. The piston block is bored out radially opposite each of the
cylinders and in the hole or each of the holes thus formed, there is inserted a spiral
spring pressing against the inner circumference of the piston ring.
We will more particularly describe our said invention with reference to the
accompanying drawings in which
Figure 1 is a vertical section, and Figure 2 a plan taken without the junk ring,
of a piston constructed according to these improvements for a double acting
engine.
A is the piston block; B the piston rod; C the junk ring; D D' are the piston
rings; E E are the inclined faces of the ends of the piston rings; F F are the
cylindrical holes bored radially in the piston block for the reception of the rams G G¹;
HH' are the wedge shaped heads of the rams fitting between the inclined faces E E
of the piston rings; I are packing rings on the rams; J J are openings from the
faces of the piston and communicating respectively with the radial cylindrical
holes F F in the rear of the rams G G₁; K K' are holes bored in the piston block,
radially thereto and each diametrically opposite to the one of the holes FF; L L are
spiral springs abutting against the bottoms of the holes K K and pressing upon the
inner faces of the piston rings; and X Y are respectively the opposite faces of
the piston.
In the drawings, the holes F F are represented as being bored in the same vertical
plane and this is the arrangement which it is preferred to adopt, but they may be
bored in other relative positions always provided that the holes F containing the
ram and K containing the spring L acting upon one piston ring, are diametrically
opposite to each other.
Assuming the piston to be at work and that the steam or other fluid pressure is
being exerted on the face X, the fluid will enter the opening J and exert its pressure
on the base of the ram G forcing its wedge-shaped head between the inclined faces of
the ends of the piston ring, thus expanding the piston ring; at the same time the
spiral spring L is pressing the opposite diameter of the piston ring into close contact
with the walls of the cylinder. It follows from the construction and arrangement of
the improved piston that the greater the fluid pressure acting upon the face of the

page_text: piston the greater will be the force acting upon the piston rings tending to expand
them, and that thus the amount of friction will be in direct proportion to the work
done instead of being practically the same for all amounts of pressure as in ordinary
pistons.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is―
(1) A piston having its ring or rings expanded by the fluid pressure acting upon
the face of the piston, constructed and arranged substantially as herein before described
and as illustrated by the accompanying drawings.
(2) In a piston to be acted upon by fluid pressure, the combination and arrange-
ment of a divided ring having its ends formed to inclined faces, a radial ram having
a wedge shaped head working between the inclined faces of the ends of the piston
ring and a radial spiral spring acting upon the inner face of the piston ring
diametrically opposite to the ram, substantially as hereinbefore described and as
illustrated by the accompanying drawings.
Dated this 8th day of October AD 1890.
WILLIAM E. HEYS,
Agent for the Applicants.