Improvements in Metallic Pistons and Piston Rings suitable for Steam and other Fluid Pressure Engines.
Year: 1897

page_text: Date of Application, 6th Mar., 1897
Complete Specification Left, 16th Nov., 1897-Accepted, 29th Jan., 1898
PROVISIONAL DI LUITICATION.
Improvements in Metallic Pistons and Piston Rings suitable for
Steam and other Fluid Pressure Engines.
I, JAMES THOMPSON MARSHALL, of the Steam Plough Works, Leeds, in the County
of York, Engineer, do hereby declare the nature of this invention to be as
follows:-
This invention of improvements in pistons, relates more particularly to pistons
that are used in horizontal cylinders, and it has for object to reduce the wear of the
lower inner surface of the cylinder, due to the reciprocation of the piston therein,
and also to reduce the wear of the lower surface of the piston in contact therewith.
For this purpose a piston suitable for use in a horizontal cylinder is provided
between its two outer or end flanges with a shoe or shoes of antifriction metal or
other suitable material, preferably made in two parts and arranged to form a joint
or junk piece between the ends of the piston rings, the outer surface of
such shoe or shoes being of the same radius as the inside of the cylinder in which
the piston is to work. The shoes, which form part of the piston, may be made of
rectangular section with inwardly projecting flanges, provided on their inner
surfaces with projections or bosses, so arranged that when placed in position in the
piston the bosses of one shoe will come opposite the bosses on the other. In the
centre of these bosses and in one or both of the shoes may be recesses in which are
placed spiral springs arranged to act against the closed ends of two opposite
recesses, or against the bottom of one recess and the plain surface of the opposite
boss, so as in each case to force the shoes apart, against the flanges of the piston.
Or the recesses may be provided with spiral springs and piston pushers or plungers
which by the action of the springs may be forced against the opposite bosses for
the same purpose, the shoes being kept in contact with the inner surface of the
cylinder by a blade spring of circular form, or other kind of spring acting on the
said projections or bosses. The ends of the piston rings joining the shoes may be
halved therewith and form a break joint or not as desired.
This invention also has reference to improvements in piston rings
for use in pistons of various descriptions, the object being to prevent
the passage of steam or other fluid through the joints formed by
the plain surfaces of the rings in contact with the inner surfaces
of the flange or flanges of the piston, and also through the joint or joints formed
by the outer peripheries of such rings and the inner periphery or surface of the
cylinder, in which the piston works, whilst at the same time providing such
piston rings with sufficient freedom of action to allow of their automatically
expanding.

page_text: For this purpose the improved piston rings whether used with my improved
pistons or with other pistons, are constructed from metal of rectangular section,
and of which preferably two are used placed side by side. On the inner
peripheries of each ring is provided a number of projections or bosses, so that
when both rings are placed in position in the piston, the bosses on one ring will
come opposite the bosses on the other. In the centre of each boss on one or both
rings may be provided recesses in which are placed spiral springs either with or
without piston pushers or plungers. These springs may- act in one case against
the bottom of opposite recesses so as to force the rings apart and against the
adjacent flanges on the piston; or the springs may act on their respective pushers
or plungers so as to force them against the opposite plain-bosses on the rings for
the same purpose. In order to cause each piston ring to automatically expand
I employ one or more circular flat bladed springs the outer periphery of
which or each of which acts against the above mentioned projections or bosses
on the piston rings. Each spring is made of a flat blade of the desired length
secured at one end of a clip, then bent to a circular form and its other end in-
serted into a hole in the reverse end of the said clip for a certain distance, leaving
a short distance at the bottom thereof for expansion, whilst being heated, so as
not to produce undue expansion on the ring. Such clips may be provided with
an orifice in their surface for the reception of the pin on the joint or junk piece
placed between the ends of each ring, which may be halved therewith to form a
break joint. Piston rings of the kind described may be used in separate grooves
of a piston, such as have a central flange or partition between the grooves.
springs in the recesses of the bosses may be provided or not with the piston pushers,
arranged to act against the sides of such central flange so as to force each ring
against the adjacent outer or end flange or cover plate; the rings may be expanded
by flat bladed circular springs as above described.
The
In a modified construction of piston the central flange between the grooves has
a number of holes extending therethrough parallel with the axis of the piston and
in which are placed spiral springs of sufficient length to act on the plain surfaces
of the bosses of the two piston rings and so force the rings against the outer
flanges or covers of the piston. The central flange instead of being traversed
with holes may have on each side thereof a number of recesses provided with spiral
springs, either with or without piston pushers, which act in a similar manner on
the plain surfaces of the bosses or projections, or on the sides of the piston rings
for the purpose mentioned.
.
Improvements in Metallic Pistons and Piston Rings suitable for
Steam and other Fluid Pressure Engines.
I, JAMES THOMPSON MARSHALL, of the Steam Plough Works, Leeds, in the County
of York, 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 of improvements in pistons, relates more particularly to pistons

page_text: that are used in horizontal cylinders, and it has for object to reduce the wear of the
lower inner surface of the cylinder, due to the reciprocation of the piston therein,
and also to reduce the wear of the lower surface of the piston in contact therewith.
In order that the nature of the invention and the manner of carrying it out
may be clearly understood, reference will be made in the following description
to the accompanying illustrative drawings, whereof
Figs. 1 and 3 are plans of two pistons according to this invention each with its
removable flange and adjacent ring removed.
Figs. 2 and 4 are cross sections thereof drawn to a larger scale than Figs. 1 and 3,
and
Figs. 5 and 6 are detail views, drawn to the scale of Figs. 2 and 4 and corres-
ponding to Figs. 3 and 4 respectively.
For the purpose referred to a piston 1 suitable for use in a horizontal cylinder
is provided between its two outer or end flanges 2 and 3 (the latter of which is
removable and secured to the body of the piston by screws 4) with shoes 5 and 6
(see Figs. 3 to 6) of suitable material such as antifriction metal, each arranged
to form a joint or junk piece between the ends 7, 7" or 8, 8 of the corresponding
piston ring 9 or 10, the outer surface 11 of each shoe being of the same radius
as the inside of the cylinder in which the piston is to work. The shoes, which
are for use in a horizontal cylinder are always placed at the bottom of the piston.
The shoes have inwardly projecting flanges 12 and 13 provided on their inner
surfaces with projections or bosses 14 and 15 so arranged that when placed in
position in the piston the bosses of one shoe will come opposite the bosses on the
other as shown in Fig. 6. In the centre of these bosses and in one (as shown)
or both of the shoes may be recesses 16 in which are placed spiral springs 17
arranged to act against the closed ends of two opposite recesses, or, as shown
in Fig. 6, against the bottom of one recess and the plain surface 18 of the opposite
boss, so as in each case to force the shoes apart and their faces 20 and 21 against
the faces 22 and 23. of the flanges 2 and 3 of the piston. Or the recesses may,
as shown, be provided with spiral-springs 17 and piston pushers or plungers 19,
which, by the action of the springs 17, may be forced against the opposite bosses
for the same purpose, the shoes 5 and 6 being kept in contact with the inner
surface of the cylinder by a suitable spring, such as a blade spring 24 of circular
form acting on the projections or bosses 14 and 15. The ordinary joint or junk
piece 5" shown in the upper part of Fig. 2 and in Figs. 2 and 2", is not opposite to
the corresponding joint or junk piece, which is not shown: and it is therefore
pressed against the adjacent face of the flange 2 by a spring 17 acting on a piston
pusher 18 and contained in a boss formed on the ring 10. The ends of the piston
rings joining the shoes may be halved therewith, as shown in Fig. 6, and form
a break-joint.
This invention also has reference to improvements in piston rings for use in
pistons of various descriptions, the object being to prevent the passage of steam
or other fluid through the joints formed by the plain surfaces of the rings in
contact with the inner surfaces of the flange or flanges of the piston, and also
through the joint or joints formed by the outer peripheries of such rings and the
inner periphery or surface of the cylinder, in which the piston works, whilst at
the same time providing such piston rings with sufficient freedom of action to
allow of their automatically expanding.
For this purpose the improved piston rings whether used with my improved
pistons or with other pistons, are constructed from metal of rectangular section,
and preferably two of them are used placed side by side. On the inner periphery
of each ring is provided a number of projections or bosses 30 or 30 so that when
both rings are placed in position in the piston, the bosses on one ring will come
opposite the bosses on the other. In the centre of each boss on one or both rings
may be provided recesses 31 in which are placed spiral springs 32 either with or
without piston pushers or plungers 33. These springs may act in one case against

page_text: .
the bottoms of opposite recesses as shown in the lower part of Fig. 2, so as to
force the rings apart and against the adjacent flanges 2 and 3 on the piston; or
the springs may act on their respective pushers or plungers so as to force them
against the opposite plain bosses 30 and 30° as shown in the upper part of Fig. 4,
on the rings for the same purpose. In order to cause each piston ring to automati-
cally expand, I employ one or more circular flat-blade springs 24 the outer peri-
phery of which, or each of which, acts against the projections or bosses 30, 30ª on
the piston rings. Each spring is made of a flat blade of the desired length secured
at one end 39 (see Figs. 2 and 5) in one end of a clip 40, then bent to a circular
form and its other end 41 inserted into a hole 42 in the reverse end of the said clip
for a certain distance, leaving a short distance at the bottom thereof for expansion,
whilst being heated, so as not to produce undue expansion on the ring. Such a
clip may, as shown in Fig. 2, be provided with an orifice 43 in its surface for
the reception of a pin 44 on the joint or junk-piece 5ª placed between the ends of
each ring. Piston rings of the kind described may as shown in Figs. 9 to 12
inclusive be used in separate grooves of a piston, such as have a central flange
or partition 25 between the grooves. The springs 32 in the recesses 31 of the
bosses 30 may be provided or not with the piston pushers 33 arranged to act
against the sides 34 and 35 of such central flange, as shown in Fig. 9, so as to
force each ring against the adjacent outer or end flange or cover plate 3 or 3ª;
the rings may be expanded by flat bladed circular springs 24 as above described.
In a modified construction of piston (see Fig. 10) the central flange 25 between
the grooves has a number of holes 36 which extend therethrough parallel with
the axis of the piston and in which are placed spiral springs 32 of sufficient
length to act either directly or as shown, through piston pushers 33, on the plain
surfaces of the bosses 30 and 30° of the two piston rings and so force the rings
against the outer flange or flange and cover-plate of the piston. The central
flange instead of being traversed with holes may, as shown in Figs. 11 and 12,
have on each side thereof a number of recesses 37 provided with spiral springs 32,
either with or without piston pushers 33 which act in a similar manner on the
plain surfaces of the bosses or projections 30 and 30% or on the sides of the piston
rings for the purpose mentioned; in this case the recesses 37 are preferably not
opposite to one another in the ring 25, but the recesses of one side of the ring 25
alternate with those on the other side, as shown in Fig. 12, which is a partial
plan of the ring 25. It is obvious that in respect of shoes 5 and 6, such as shown
in Figs. 3 to 6, similar arrangements may be made in pistons having central
flanges or partitions 25, as shown in Figs. 7 and 8; Fig. 7 shows an imperforate
central flange, the various reference-numerals corresponding to those of Fig. 6;
and Fig. 8 shows a central flange 25 having holes 26 therethrough and containing
springs 27 provided with piston pushers 28.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is:-
1. Pistons in which shoes forming joint or junk pieces for the piston rings,
are forced by springs against lateral surfaces of piston-flanges, substantially as
described and shown..
2. Piston rings which are forced against lateral surfaces of piston-flanges by
springs and at the same time are automatically expanded, substantially as described
and shown.
3. In pistons, shoes and pressing devices therefor, constructed, arranged, and
operating substantially as herein before described with reference to and shown
respectively in Figs. 3, 4, 5, and 6, in Fig. 7 and in Fig. 8 of the drawings
annexed.
4. In pistons, rings and pressing devices therefor, constructed, arranged, and
operating substantially as hereinbefore described with reference to and shown

page_text: Figs. 1 and 2, in Figs. 3, 4, and 5, in Fig. 9, in Fig. 10, and in Figs. 11 and 12
f the drawings annexed.
Dated this 15th day of November 1897
R. E. P. CRAVEN,
Registered Patent Agent,
22, Victoria Chambers, South Parade, Leeds,
Agent for the Applicant.