Improvements in Steam and other Fluid Pressure Engines.
Year: 1897

page_text: Date of Application, 11th June, 1897
Complete Specification Left, 9th Apr., 1898-Accepted, 11th June, 1898
PROVISIONAL SPECIFICATION.
Improvements in Steam and other Fluid Pressure Engines.
I, ARTHUR FORBES SCOTT, M.I. Mech. E., of 27, Welbury Drive, Bradford, in
the County of York, Engineer, do hereby declare the nature of this invention
to be as follows:-
This invention relates chiefly to improvements in steam and other fluid pressure
engines particularly engines having receivers for maintaining the parts in constant
thrust and dividing the expansion into stages some types of which I describe in
Specifications of Patents granted to me dated 1886 (No. 15858), 1889 (No. 12258)
and 1892 (No. 21955); and its object is to obtain a more perfect balance and better
drainage in high speed engines with economy of steam and means of regulating
the expansion thereof.
These improvements are hereinafter described as applied to steam engines having
inverted vertical cylinders with downward thrust, though applicable to other types
of engine. The letters h.p. and 1.p. stand for high pressure and low pressure
respectively.
In one form of compound engine I place the h.p. cylinder above the 1.p. and
take the h.p. piston rod through the 1.p. piston which contains rings or packing
bearing against the h.p. rod or against an intervening fixed sleeve which may
be secured in and form part of the h.p. stuffing box. The 1.p. piston is preferably
fitted with two rods which pass through glands and connected with two cross-
heads or their equivalent below (although one hollow rod may be used where space
permits of the motion of the piece connecting same with the aforesaid crossheads).
The shaft is formed with the h.p. and l.p. cranks opposite or thereabouts. The
strokes may be equal but I prefer to make the h.p. rather longer mainly so that
the h.p. crank shall balance the two l.p. cranks.
The adjacent sides of the two pistons are preferably open to one another with
a receiver space between and a receiver is placed on or around the h.p. cylinder
in a position convenient for drainage and the whole arranged with suitable ports
and valves, the latter may be worked off the connecting rod by a modified form
of Joy's valve gear adapted to some single acting engines. This gear consists of
a horizontal lever (or levers) one end of which is fixed to or about the middle of
the h.p. connecting rod or to a projection on the same the other end is connected
by a link to the valve crosshead and a point between the two nearer the valve end
is connected by a radial link with a point (preferably) below, which latter is
capable of movement in a curved or inclined slot or on a radial arm by hand or
governor so as to alter the cut off etc., in both cylinders.
When the h.p. piston is at the top and the 1.p. at the bottom, the valve is
descending and a part of it admits steam to the top of the h.p. piston while another
part admits steam from the inter-piston space to the bottom of the 1.p. piston.
After certain portions of their strokes are made the steam is cut off from the
remote sides of the two pistons and compression taking place between them keeps
the 1.p. piston in constant thrust. Towards the end of the stroke parts of the
ascending valve connect the h.p. receiver first with the top of the h.p. piston and

page_text: then also with the inter-piston space while another part connect the underside of
the l.p. piston with the exhaust. During the next stroke this receiver is first cut
off from the inter-piston space (when compression in the h.p. receiver begins) also
towards the end of the stroke from the top of the h.p. piston; and about this point
the exhaust is closed and afterwards the two sides of the l.p. piston are connected
again as already described.
It will be observed the steam expands in three stages: 1st. above the h.p. piston
2nd. in the inter-piston space and 3rd below the 1.p. piston and the gear described
may vary the expansion in each stage. Where a wide range of cut off is desired
in the h.p. cylinder I sometimes arrange the l.p. piston with a cut off piece or pieces
for closing or partly closing the top 1.p. port at a certain point after the middle
of its up-stroke so as to limit the lateness of cut off and maintain the constant
thrust. By using a 1.p. receiver in connection with the valve the inter-piston
space may be reduced as described later.
The valve gear I have described may be used in several of the engines set forth
in my former specifications or in other similar engines. When the valve is required
to work in the opposite direction the gear may be worked off one or both 1.p. con-
necting rods or the motion reversed by links or other means, or a gear may be
employed worked off the lower part of the h.p. connecting rod in the following
manner: A link is taken diagonally from the connecting rod to one end of a
lever inclined towards it diagonally in the opposite direction. The lower end of
the latter is pivoted in a slot and a link is taken from a point on the lever to the
valve cross-head. As the crank goes over the top centre the valve is rising and
by moving the fulcrum end of the lever in the slot towards the crank the cut off
is made earlier.
This engine can be made so that the incrita is also approximately balanced by
arranging the l.p. crank in the centre and by taking the thrust of the h.p. piston
by side rods outside of the 1.p. cylinder or two h.p. cylinders or first and second
expansion cylinders might be used on the two cranks opposite the 1.p. In another
plan the h.p. rod is taken between two 1.p. cylinders acting on opposite cranks. A
simple form of the engine is made by placing the h.p. above the 1.p. cylinder and
so that its rod will pass to the side of the 1.p. but this form is not balanced end-
ways. The weights of the h.p. and 1.p. pistons multiplied by their strokes are
equalized in each case.
A part of this invention relates to an improved method of using receivers in
connection with cylinders in which steam is admitted to one side of the piston and
thence to the other side of the same the steam being expanded below while com-
pression takes place above as I set forth in a former Patent No. 12258 of 1889.
The present improvement consists in connecting the receiver with the top side of
the piston from a certain point after cut off until a point near the top of the stroke
so that when steam is admitted there is less surface to induce initial condensation
and the back pressure is reduced. In the first described engine when it is desired
to divide the expansion into more stages I sometimes fix above the h.p. cylinder
another cylinder and piston to the top of which steam is admitted on the down
stroke and transferred thence to the underside during the up stroke whence it
passes to the second cylinder next down stroke. In another arrangement instead
of adding a cylinder I separate the h.p. and 1.p. cylinders and place an extra
receiver between them and the steam is then passed during successive strokes to
the top of h.p., bottom of h.p., into the extra receiver, top of 1.p., bottom of 1.p., and
finally the exhaust. Or the extra receiver may not be used. The distribution in
one or both cylinders may be in the manner shown in the last paragraph.
In order to avoid having unnecessary pressure on the pins of the valve gear I
mount an extra part on the top of the valve above which is a space to which steam
is admitted at top stroke by a part of the valve itself and at the bottom of its stroke
a certain portion of the steam passes through a hole down the valve into one of
the receivers or cylinders where the pressure is lower, At light load the down-
ward travel of the valve may not be sufficient for much steam to pass. When

page_text: it is desired to reduce the pressure on the valve at the beginning as well as the
end of its stroke I admit a fixed charge of steam from around the valve stem-into
the valve receiver (or I admit the steam through a small opening) and arrange
the size of discharge hole and time of exposure to the lower pressure so as to tend
to maintain a fairly even control of the valve at different loads. Steam may be
admitted to a piston in a similar way.
In an important modification of the first described engine I employ a central
valve for the distribution of steam which I preferably construct as follows; in the
centre of the l.p. cylinder is a liner around which the 1.p. piston works, inside of
the liner the bottom part of the valve works and this has a tubular stem: extending
downwards through packing and at the lower end of this stem a socket is fixed
containing a pin or pins for connection to the valve gear, also a gland may be
provided here for making tight the h.p. rod which works through this tubular
stem. The h.p. rod is secured to a trunk or downward extension of the h.p. piston
which is bored out to receive part of the valve. An upper part of the valve works
in a liner in the h.p. cylinder cover around which is the h.p. receiver and the h.p.
port. The bottom part of the valve is connected with the upper portion prefer-
ably by rods passing through holes in the bottom end of the aforesaid h.p. piston
trunk which in this case works through a cap on the l.p. valve liner. But the
connection may also be made by a cotter through a slot in the h.p. rod with a cen-
tral rod therein, or an upward extension of the bottom part of valve may be con-
nected by cotter or studs through slots in the h.p. piston trunk with the middle
part of valve and in the latter case the 1.p. valve liner requires no cap. To
save height I prefer the middle part of valve to be in the form of a trunk packed
by rings in the h.p. piston and containing ports at the lower end. To transmit
the motion of the expansion gear as above described to the central valve I pre-
ferably connect it by a link with levers below which are pivoted to a fixed point
at one end the other ends being connected by long links with the pins on the
socket alluded to above. These links pass through holes in the h.p. gudgeon pin.
The ports and valve are so arranged that steam is distributed in a similar manner
to that set forth above but the steam is passed from the top of the h.p. piston to the
inter piston space by the trunk part of the valve rising above the h.p. piston which
gives a large port opening with early cut off and good drainage, but I may use
the top part of valve for the purpose. The cover of 1.p. piston may be formed with
a projection which closes ports in the valve liner during the up stroke and limits
the lateness of cut off. An extra part may be placed on the valve for the purpose
of reducing the pressure on the pins of the gear as above described.
The receiver and steam port may be arranged between the cylinders but I pre-
fer the plan set forth. Particularly when a central valve is used I may work the
valve from a certain point in a diagonal lever one end of which is attached to a
projection on the connecting rod and the other end to one end of a diagonal link
the other end of the latter being moved in a slot or equivalent to alter the cut off.
In another arrangement I work the valve by a link or rod from a certain point
or slot in a lever, the mean position of the latter being approximately horizontal.
One end of this lever is jointed to the connecting rod by a diagonal link. The
fulcrum of the lever is capable of being moved in a slot or by a radial link so as
to alter the cut off.
In my Specification No. 21955 of 1892 in Figures 7 and 8 I describe some
engines in which an extension of the h.p. piston or crosshead acts as a valve for
the 1.p. cylinder. These improvements include certain modifications of such
engines in which I place the h.p. above the 1.p. cylinder and the connection or
extension of the h.p. piston which acts as a valve works in a central liner around
which the 1.p. piston works. The 1.p. piston has preferably two rods and works
on a pair of cranks. The underside of the h.p. piston may be always open to the
top of 1.p. piston or its steam distribution may be as in the original engine. Steam
may be admitted to the h.p. cylinder by the motion of the piston, or a separate
valve may be used for this purpose and partly for the exhaust therefrom to the

page_text: 1.p. cylinder, the valve being in this case preferably connected with a governor.
When more expansion is required I may construct the h.p. piston with a trunk
below, the steam being admitted first to the underside and then transferred to the
larger area above, the parts being proportioned so that the constant thrust is
maintained. This arrangement is applicable to other engines.
This type of engine with three cranks as described in my Specification No. 21955
of 1892 line 7 to 16 page 10 I now construct with the cylinders above one another
when a more perfect absence of vibration is required. The 1.p. piston has two
rods connecting with a pair of cranks. In the centre of the piston is a liner in
which an extension of the intermediate piston works and acts as a valve for the
1.p. cylinder, this extension is tubular and the lower part connects with a pair of
cranks below and through this extension the h.p. piston rod works connecting
with a middle crank. The adjacent sides of adjacent piston are preferably open
to one another. The intermediate piston may conveniently have a shorter stroke
than the others. The engine may be modified by arranging the h.p. cylinder or
two cylinders to operate a pair of piston rods and cranks outside the others, or two
1.p. cylinders may be used similarly working outside the others.
The effect of the obliquity of connecting rods and pistons working in opposite
directions is to disturb the balance of the inertia of the parts to a certain extent,
and a part of this invention relates to means for causing the motion of the piston
to coincide more nearly with the vertical motion of the crank. To effect this I
construct the crosshead in two parts working in the same guide or one may work
within the other. The top end of the rod is connected to one portion and the
other portion is connected by a pair of short links with a point in the connecting
rod a certain distance from the top end. The piston rod is connected with the
latter portion. The side motion of the connecting rod moves this portion relatively
to the other and tends to counteract the effect of the obliquity of the rod.
In tandem compound engines of similar design to the engines first described in
my Specification No. 12258 of 1889 when it is desired to accelerate the pistons
upwards by the steam while maintaining the constant thrust principle I may
attach to the h.p. piston rod a small piston or trunk working in a cylinder fixed
between the h.p. and l.p. cylinders. Steam is admitted alternately to the two sides
of the h.p. piston, that from the top passing to the underside of the 1.p. piston
and the 1.p. receiver and that from the space below the h.p. piston passing first
to the top side of the 1.p. piston or 1.p. receiver and next stroke to the underside
of the piston. It is arranged so that the pressure below the h.p. piston acceler-
ates the pistons without knock. The small piston may be used for cut off purposes.
The engines described herein may be constructed with their cylinders out of
line with the crank centre and may exhaust into other cylinders or be worked in
conjunction with other engines or parts thereof of similar construction to those
described in this and my former specifications and in some cases they may be
reversed by link gears or in other suitable ways.
Dated this 9th day of June 1897
Improvements in Steam and other Fluid Pressure Engines.
I, ARTHUR FORBES SCOTT, M.I. Mech. E., of 27, Welbury Drive, Bradford, in
the County of York, Engineer, do hereby declare the nature of this invention

page_text: 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 chiefly to improvements in steam and other fluid pressure
engines particularly engines having receivers for maintaining the parts in constant
thrust and dividing the expansion into stages some types of which I describe in my
Specifications of Patents granted to me dated 1886 (No. 15858), 1889 (No. 12258)
and 1892 (No. 21955); and its object is to obtain a more perfect balance and better
drainage in high speed engines with economy of steam and means of regulating
the expansion thereof.
These improvements are hereinafter described as applying to steam engines having
inverted vertical cylinders with downward thrust, though applicable to other types
of engines. The letters h.p. and l.p. stand for high pressure and low pressure
respectively.
In one form of compound engine I place the h.p. cylinder above the 1.p. and
take the h.p. piston rod through the 1.p. piston which contains rings or packing
bearing against the h.p. rod or against an intervening fixed sleeve which may be
secured in and form part of the h.p. stuffing box. The 1.p. piston is preferably
fitted with two rods which pass through glands and connected with two crossheads
or their equivalent below (although one hollow rod may be used where space per-
mits of the motion of the piece connecting same with the aforesaid crossheads).
The shaft is formed with the h.p. and 1.p. cranks opposite or thereabouts. The
strokes may be equal but I prefer to make the h.p. rather longed mainly so that
the h.p. crank shall balance the two 1.p. cranks.
To fully describe my, invention reference is made to the accompanying sheets
of drawings forming a part of this specification, in which similar letters of refer-
ence indicate corresponding parts in each of the figures.
The arrows are shown to indicate the direction of motion of the parts to which
they are applied.
Figures 1 and 2 represent vertical sections at right angles to each other of one
form of my improved engine, and Figure 3 is a sectional view of part of the valve
gear. I place the h.p. cylinder H above the 1.p. cylinder L and take the h.p.
piston rod H3 from the piston H2 through the 1.p. piston L which contains packing
rings L bearing against the h.p. rod or against an intervening fixed sleeve Ö
which latter may be secured in and form part of the h.p. stuffing box H7. The 1.p.
piston L is preferably fitted with two rods L³ which pass through glands L' and
are connected with two crossheads L' or their equivalent below. The shaft is
formed with the h.p. and 1.p. cranks opposite or thereabouts. The strokes may be
equal but I prefer to make the h.p. rather longer mainly so that the h.p. crank Ho
shall balance the two 1.p. cranks L.
The adjacent sides of the two pistons H2 and L2 are preferably open to one
another with a receiver space R2 between and a receiver R is placed on or around
the h.p. cylinder H in a position convenient for drainage. The valve V may be
worked off the connecting rod H5 by a modified form of Joy's valve gear consist-
ing of a horizontal lever (or levers) T one end of which T is pivoted to or about
the middle of the h.p. connecting rod H5 or to a projection on the same the other
end is connected by a link W to the valve crosshead W and a point T5 between
the two nearer the valve end is connected by a radial link U with a pin Z' in the
block U below, which latter is capable of movement in a curved or inclined slot Y
by a radial arm Z on the shaft 72 by hand or governor so as to alter the cut off etc.
in both cylinders.
When the h.p. piston H2 is at the top and the l.p. piston L2 at the bottom as
shown in Figures 1 and 2 the valve V is descending and a part of it namely ring 1
admits steam from inlet S through port B to the top of the h.p. piston while ring 3
of the valve admits steam from the inter-piston space R2 through ports G and J
to the bottom of the 1.p. piston L³. After certain portions of their strokes are
made the steam is cut off from the remote sides of the two pistons by rings 1 and 3
as the valve ascends and compression taking place between the pistons keeps the

page_text: 1.p. piston in constant thrust. Towards the end of the stroke rings 1 and 2 of
the ascending valve connects the h.p. receiver R first with the top of the h.p.
piston H by port B and then also with the inter-piston space R³ by ports B and D
whilst ring 3 connects the underside of the 1.p. piston L³ by port J with the
exhaust E. Steam also passes from above H2 through drainage holes N at the
end of the stroke so that a negative lead by ring 2 does not effect the admission
to R. During the next stroke this receiver R is first cut off from the inter-piston
space R2 by 2 descending and closing D (when compression in the h.p. receiver
begins) also towards the end of the stroke from the top of the h.p. piston by 1
closing B, and about this point the exhaust is closed by 3 covering and after-
wards the two sides of the 1.p. piston L2 are connected again as already described.
It will be observed the steam expands in three stages; 1st. above the h.p. piston,
2nd. in the inter-piston space, 3rd. below the 1.p. piston, and the gear described
may vary the expansion in each stage. Where a wide range of cut off is desired
in the h.p. cylinder I sometimes arrange the 1.p. piston with a cut off piece (or
pieces) as shown by the broken line L Figure 1 which closes or partly closes the
port G at a certain point about the middle of its up-stroke so as to limit the late-
ness of the cut off to the underside of the 1.p. piston L2 and so maintain the con-
stant thrust. In that case I provide a separate admission port into the receiver R²
above the port G. By using a 1.p. receiver (part of which is shown at R³) connect-
ing with the valve casing by port G2 this largely supplants the inter-piston space R²
which may consequently be reduced. This method of using a receiver is described
later in reference to Figure 11.
For extremely high speeds I may abolish the ports N and G and the ring 2 of the
valve and place port G2 higher up so that the h.p. piston exhausts into the receivers R
and R and steam passes direct from the receivers to the underside of the 1.1.
piston L³.
As each piston gets towards the end of its down stroke the pressure
below may be greater than that above which aids in overcoming the inertia of each
piston. The inter-piston space may be filled by leakage or a pipe from the space F'
above the valve may be taken to the cock N2 which is adjusted so as to admit a
more or less small quantity of steam as the pistons commence to recede from one
another and when the pressure in F is at about its maximum.
The valve gear I have described may be used in several of the engines set forth
in my former specifications or in other similar engines. When the valve is
required to work in the opposite direction relative to the motion of the pistons
the valve gear may be worked off one or both 1.p. connecting rods or the motion
reversed by links or other means, or a gear may be employed worked off the lower
part of the h.p. connecting rod in the following manner:-Referring to Figure 17,
a link P2 is taken diagonally from a point P³ on the connecting rod H5 to one
end P of a lever P inclined towards it diagonally in the opposite direction. The
lower or outer end 15 of the latter is pivoted in a slot which may be struck out
from a centre 1" as shown by the broken lines and a link W is taken from a
point P on the lever P to the valve crosshead W³. As the crank goes over the
top centre the valve is rising as shown by the arrow and by moving the fulcrum
end P5 of the lever P in the slot towards the crank the cut off is made carlier.
The gear shown in Figure 18 is the same as that shown in Figure 17 but with
the apex P of the link P2 and lever P pointing downwards instead of upwards
and as similar letters are used the above description also applies. Should it be
desired to make the valve work in the opposite direction to that indicated by the
arrow I connect the valve rod W with the point P5 and fulcrum the point Po in a
similar slot struck out from a point P8.
This engine can be made so that the inertia is also approximately balanced by
arranging the 1.p. piston to act on one l.p. crank in the centre and by taking the
thrust of the h.p. piston through a cross piece or otherwise to a pair of side rods
which pass outside of the 1.p. cylinder and transmit the power to a pair of h.p.
cranks one on each side of the 1.p. crank and opposite thereto, or a pair of h.p. cylin-
ders may be used on the outside cranks, or first and second expansion cylin-

page_text: ders may be used one on each of the same and in the latter case I prefer to make
the distribution to the first cylinder similar to that described later in reference
to Figure 11, the steam afterwards passing from the underside of the first to the
top side of the second cylinder in a similar manner to that described later in
reference to Figure 4, and thence as already described. In another plan the h.p.
rod is taken between two l.p. cylinders which act on a pair of cranks which are
opposite to the central h.p. crank.
.
A simple form of engine partly shown in section and plan in Figures 5 and 6,
is made by placing the h.p. cylinder H above the 1.p. cylinder L and so that its
rod H3 passes close to the side of the 1.p. cylinder L. The balance and drainage
are better and the engine more compact than would be the case if the cylinders
were side by side on the same level. As the 1.p. piston L² rises steam passes from
the inter-piston space R2 through the port G to the underside of the piston La
until the cut off piece Lº partly closes the entrance to the port G about half stroke,
which at full load may be before the complete cut off by the valve as described
in reference to Figures 1 and 2. This arrangement permits of the valve V being
placed close to both cylinders therefore the engine can be made with very short
ports.
A part of this invention relates to an improved method of using receivers in
connection with cylinders in which steam is admitted to one side of the piston and
thence to the other side of the same the steam being expanded below whilst com-
pression takes place above as I set forth in a former Patent No. 12258 of 1889.
The present improvement in this method is illustrated by the sectional views
Figures 11 and 12 and consists in connecting the receiver R³ with the top side of
the piston H2 from a certain point after cut off during the down stroke until a
point near the top of the up stroke so that when steam is admitted there is less
surface to induce initial condensation and the back pressure is reduced. This
is illustrated by Figure 11, in which the valve V is rising and steam
passes from
inlet S through port B to the top of the piston H³ whilst that below it passes
through the port B² to the exhaust or to another cylinder. Shortly after the valve
has descended and closed the admission port S ring 1 opens port B and the top of
the piston is connected to the receiver R³ by the hollow part of the valve and
port G2, and the receiver and cylinder volumes expand together until the end of
the stroke, when the exhaust is closed and the two sides. of the piston and the
receiver connected by ring 3. Shortly after half the return stroke is made ring 3
cuts off the steam passing to the underside of the piston and compression into the
receiver R³ begins from above the piston and this continues until near the top of
the stroke when the receiver is disconnected therefrom by ring 1, and I proportion
the parts so that the pressure in the receiver is raised to about the same as that
existing above the piston when the receiver is opened thereto. Figure 12, shows
how a similar distribution may be effected with a central valve V. Ring 1 of
the valve which is rising admits the steam from S through the hollow ring 2 and
port B, the ring 2, controls the connection of the receiver R³ by port G2 with the
cylinder, and ring 3 controlling port B2 admits steam to and from the underside of
the piston H². I may apply variable expansion gears such as described in reference
to Figures 18 and 19 to the cylinders shown in Figures 11 and 12 respectively,
and should a late cut off be desired I prefer to make the piston deeper so that
the top edge of the same may partly cut off the steam, flowing to the underside of
the piston as described above, a separate admission port being provided. A
receiver may be similarly applied to the 1.p. cylinder of a compound engine as
described in reference to receiver R³ and port G2 in Figure 1.
In the engine described with reference to Figures 1 and 2 when it is desired to
divide the expansion into more stages I sometimes fix above the h.p. cylinder (as
shown in Figure 4) another cylinder X and piston X2 to the top of which steam is
admitted on the down stroke through port M and transferred thence to the under-
side through port K during the up stroke whence it passes to the second cylin-
der H next down stroke through port B, a small receiver space R' may be provided

page_text: into which X2 can compress after cut off to the second cylinder. In another
arrangement instead of adding a cylinder I separate the h.p. and l.p. cylinders
and place an extra receiver between them and the steam is then passed during
successive strokes to the top of the h.p., bottom of h.p., into the extra receiver,
top of 1.p., which
the 1.p. receiver as heretofore, bottom of 1.p., and finally the
exhaust. There are thus in this case four stages of expansion. Or the extra
receiver may not be used in which case the distribution remains the same for the
h.p. cylinder but the valve is arranged to pass the steam direct to the l.p. receiver
or cylinder. As before receivers are provided to prevent "knock in the bearings.
The distribution in one or both cylinders may be in the manner shown in the
last paragraph with reference to Figures 11 and 12.
"
Referring to Figures 1, 4, 7, 8 and 9, in order to avoid having unnecessary
pressure on the pins of the valve gear I mount an extra part or ring 4 on the top
of the valve V, above which is a space F to which steam is admitted at the top
stroke by ring 4 itself through a small hole or holes A. and at the bottom of its
stroke a certain portion of the steam passes through a hole A down
the valve V by a port A³ (or port D in the central valve engine
Figures 7 and 8) into the receiver R or other place where the pres-
sure is suitably lower. At light load the downward travel of the
valve may not be sufficient for much steam to pass. When it is desired to reduce
the pressure on the valve at the beginning as well as at the end of its stroke I admit
a fixed charge of steam from around the valve stem between rings 4 and 1 into
the valve receiver F (or I admit steam through port A which is made small so as
to suitably limit the amount entering) and arrange the capacity of space F and
the size of discharge hole A3 and time of exposure of the latter to the lower pres-
sure of receiver R so that at partial loads when the valve does not descend so far
there is a shorter exposure to the receiver but as at that load this receiver pressure
is less than at greater loads a fairly even control of the valve is maintained.
In an important modification of the first described engine I employ a central
valve for the distribution of steam which I preferably construct as illustrated by
Figures 7 and 8 which represent vertical sections at right angles to each other.
In the centre of the 1.p. cylinder L is a liner O around which the 1.p. piston L2
works, inside of the liner the bottom part 3 of the valve V works and this has a
tubular stem W5 extending downwards through packing V7 and at the lower end
of this stem a socket W is fixed containing a pin or pins W³ for connection to
the valve gear, also a gland H7 may be provided here for making tight the h.p.
rod H³ which works through this tubular stem W5. Figure 9, is a separate view
of the valve partly in section. The h.p. rod is secured to a trunk or downward
extension H of the h.p. piston H2 which is bored out to receive the trunk part 2
of the valve. Figure 10, is a separate cross section of the piston. An upper
part 1 (as well as the part 4 hereinbefore referred to) of the valve works in a liner
in the h.p. cylinder cover around which is the h.p. receiver R and the h.p. port B.
The bottom part 3 of the valve is connected with the upper portion preferably by
rods V8 passing through holes H15 in the bottom end of the h.p. piston trunk H
which in this case works through a cap (2 on the l.p. valve liner 0. But the con-
nection may also be made by a cotter joining 3 through a long slot in the h.p. rod
with a central rod working inside the latter and which takes the place of the
rods V8. Or instead the long slots may be formed in the h.p. trunk H which
works inside an upward extension of the valve part 3 which is joined by a cotter or
studs through the slots with the valve trunk 2 and in the latter case the l.p. valve
liner requires no cap. To save height I prefer the middle part of the valve to
be in the form of a trunk 2 packed by rings V18 in the h.p. piston H³ and con-
taining ports D³ at the lower end.
To transmit the motion of the expansion gear (as described above in reference
to Figures 1 and 3) to the central valve I preferably connect it by links W², Wa
with levers T2, T3 below, which are pivoted to a fixed point at one end T, the
other end T8 being connected by long links W, W with pins W³, W³ on the

page_text: socket W. These links pass through clearance holes in the h.p. gudgeon pin and
crosshead. It is evident that I may pivot one end of T to a fixed point at the
other side of the crank chamber and the other end of T to the link W the rods W
being connected to another point on T. The travel of the valve is then less but
I increase it by making pins T and T further apart. This gear partly owing
to the action of the short links W2 gives a free exhaust at early cut off suited to
the small clearance of the central valve engines. The ports and valves are so
arranged that steam is distributed in a similar manner to that set forth above, as
will be understood owing to the similar lettering employed, but the steam is
passed from the top of the h.p. piston H through ports G2 and D3 to the inter-
piston space R2 by the trunk part 2 of the valve rising above the rings V12 in the
h.p. piston, which gives a large port opening with early 1.p. top cut off and good
drainage. The cover of the 1.p. piston may be formed with a cut off piece or pro-
jection L which closes or partly closes ports G in the liner O and limits the late-
ness of cut off as described above.
The receiver and steam ports may be arranged between the cylinders but I
prefer the plan set forth.
In an arrangement of valve gear illustrated by Figures 19 and 20, (which
show the valve working in opposite directions as indicated by the arrows) I work
the valve by a link or rod W from a certain point P in an approximately horizontal
lever P. One end P of this lever P is jointed to the connecting rod H³ by a diagonal
link 12 The fulcrum P5 of the lever is capable of being moved in a slot which
may be struck out from a centre 17 as shown in broken lines, so as to alter the
cut off, to effect which a radial link may be used working on the centre P7, but in
the case of Figure 20 I can employ other suitable means of moving P5 in the slot.
The valve gear (Figure 19) may be used to work the valve shown in Figure 12
and to adapt the gear (Figure 20) to work the valve shown in Figures 7, 8 and 9
I preferably use narrower crossheads of rectangular section so that the rod W may
pass outside the same to the pin W3 on the socket W on the valve stem: W5 as
shown in Figure 20. A single rod W, lever P and slot may be used or they may
be duplicated on the other side of the crosshead. In Figure 19 a divided con-
necting rod is used. In Figures 19 and 20 as in Figures 17 and 18 I may use
a straight slot as being approximately correct.
In my Specification No. 21955 of 1892 in Figures 7 and 8 I describe some
engines in which an extension of the h.p. piston or crosshead acts as a valve for
the h.p. cylinder. These improvements include certain modifications of such
engines shown in Figures 14 to 16 in one of which shown in Figure 14, (which is
a sectional elevation of the upper portion) I place the h.p. cylinder H above the
1.p. cylinder L and the connection or extension H20 and H of the h.p. piston H2
which acts as a valve works within a central liner which in this case is divided into
The liner O may
two parts and around the top part 0 the 1.p. piston works.
however be separated from the h.p. cylinder and form part of the liner 0³ within
which H2 works. The 1.p. piston L2 is shown with two rods L³ and works on a
pair of cranks L which are made at an angle of preferably 142 degrees with the
central h.p. crank H as shown in Figure 15 which is an end view of the crank
shaft. The underside of the h.p. piston or its steam distribution may be as in
the original engine described in reference to Figures 7 and 8 in my former
Specification No. 21955 of 1892. Steam may be admitted to the h.p. cylinder
by H on the piston H2. It enters by the port S into the receiver R and when H2
has descended it passes by ports N to receiver R2 and when piston L² gets to the
bottom H20 rises above port G2 and steam passes from above to below L³
through G, G2 and opening J. As L rises G2 is closed by H2 and compression
begins above and expansion below piston L2 and when the latter gets to the top
steam from below is admitted to exhaust E by H2. The steam in R is compressed
during the upstroke of H2. Although with the adjacent sides of the pistons open
to one another there is a small negative diagram from the under-
side of the piston H2 it increases the plus diagram from above piston L³.

page_text: The pistons however may have their adjacent sides not always open to one another
as in Figure 16. A separate valve may be used to admit the steam to H2 and partly
for the exhaust therefrom to the l.p. cylinder, the valve being in this case prefer-
ably connected with a governor.
This type of engine with three cranks as described in my Specification No. 21955
of 1892 lines 7 to 16 page 10 I now construct with the cylinders above one another
when a more perfect absence of vibration is required, and in this case I may
arrange three cylinders in line as described in the Provisional Specification of
this application, but to save height I prefer the modification mentioned therein
in which two h.p. cylinders are employed instead of one, as shown in Figure 16
(a vertical section), in which the distribution of steam in the intermediate
cylinder H and the l.p. cylinder L is very similar to that described in reference
to Figure 14 but the pair of h.p. cranks X, the intermediate pressure crank HỒ
in the centre, and the pair of 1.p. cranks L are set at an angle of about 120 degrees
to one another, and the cranks are of equal throw, and the bottom and top sides
of the h.p. and intermediate and the intermediate and 1.p. pistons respectively
are shown not permanently open to one another, and I may admit a little steam
to the receiver spaces below H2 and X2 through holes and cocks S3 and S4 when
the pistons are about bottom stroke. Steam is admitted from S by a valve (or
pair of valves) V on the 1.p. piston L² (which valve may be fixed instead on X2)
through a port M to above the pistons X2 and in the position shown the pistons X³
are about to uncover the port or ports B to admit steam from above the pistons X³
to receiver R. After cut off compression takes place above the pistons X2 in
receiver R. When H2 descends it uncovers port N through which steam passes
to R2 and thence through port G and opening J to the underside of Le whence it
is exhausted by H21 in a similar way to that described in reference to Figure 14.
Pistons X2 and H2 entrap and compress steam in the spaces below them which
may be supplemented as alluded to above by steam admitted at about bottom
stroke by rings X' and H20 on their respective rods. The top sides of pistons X2
are connected by a port K5 and the bottom sides are connected by a port K.
The engine may be modified by arranging two 1.p. cylinders to work outside
of the h.p. and intermediate cylinders.
The effect of the obliquity of the connecting rods and pistons working in opposite
directions is to disturb the balance of the inertia of the parts to a certain extent,
and a part of this invention relates to means for causing the motion of the piston
to coincide more nearly with the vertical motion of the crank, as illustrated by
Figures 21 and 22 which are vertical sections at right angles to each other, and
Figures 23 is a similar view slightly modified the guide being omitted. To effect
this I construct the crosshead in two parts H and H8 which may work in the same
guide, or one H8 may work within the other H. The top end H of the rod H5
is connected to one portion H8 and the other portion H is connected by a pair of
short links Q with a point Q3 in the connecting rod H a certain distance from the
top. The piston rod, shown broken away, is connected with the top of H. The
side motion of the connecting rod He moves this piston H relatively to H³ and
tends to counteract the effect of the obliquity of the rod. In Figure 23 only one
pin Q2 is used and it extends right through the crosshead H an opening K7 being
made in the connecting rod to permit of this, thus enabling the links Q to be con-
nected by one bearing Q5 working on Q2.
In tandem compound engines of similar design to the engines first described in
my Specification No. 12258 of 1889 when it is desired to accelerate the pistons
upwards by the steam while maintaining the constant thrust principle I attach
to the h.p. piston rod as shown in Figure 13, (which is a sectional view of the
cylinders) a piston or trunk F3 working in a cylinder F2 fixed between the h.p.
cylinder H and the l.p. cylinder L. Steam from inlet S is admitted alternately
by ring of the valve V through ports 1 and B2 to the two sides of the h.p.
piston H2, that from the top side of H2 passing (as in the position shown) through
port B, the hollow parts 1 and 2 of the valve, and port J, to the underside of the

page_text: 1.p. piston L, and by port G to the l.p. receiver, and that from the space R below
the h.p. piston H³ passing first by ports 13 and G to the top side of the 1.p. piston
or 1.p. receiver R2 and next stroke to the underside by ports G and J, the steam
below L passing to the exhaust E during the down stroke through port J. The
steam admitted to the underside of the piston H2 may be cut off early by the small
piston F3 and expands in three stages whilst that admitted above H2 expands in
two stages. The parts are proportioned so that the pressure below the h.p. piston
at the beginning of the upstroke accelerates the pistons without knock.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is:-
:-
1. A compound engine having the adjacent sides of the pistons open to one
another and having the h.p. piston working through the 1.p. piston and acting
on one crank whilst the 1.p. piston acts on a pair of cranks set opposite to the
other crank in which the steam is first expanded on the side of the h.p. piston
remote from the cranks and finally on the side of the 1.p. piston adjacent to the
cranks whilst during the latter parts of their return strokes the 1.p. piston com-
presses steam in the inter-piston space or receiver and the h.p. piston in another
receiver in order to keep the bearings in constant thrust, substantially as herein
shown and described.
2. A single-acting compound engine having a main shaft with one central
crank and a pair of cranks set opposite to and one on each side of the other crank and
in which the steam is first expanded on the side of the h.p. piston or pistons
remote from the shaft and finally on the side of the 1.p. piston or pistons adjacent
to the shaft, whilst during the latter parts of their return strokes the 1.p. piston
compresses steam in the inter-piston or receiver space or spaces and the h.p. piston
in another receiver or receivers in order to maintain the connecting rod bearings
in constant thrust against the crank pins, substantially as herein shown and
described.
3. A single-acting compound engine having the h.p. cylinder fixed on the top
of the 1.p. cylinder and their pistons working on opposite cranks in which steam is
first expanded on the side of the high pressure piston remote from the crank and
finally on the side of the 1.p. piston adjacent to the cranks, whilst during the
latter parts of the return strokes the 1.p. piston compresses the steam in the inter-
piston space or receiver and the h.p. piston in another receiver in order to maintain
the connecting rod bearings in constant thrust against the crank pins, substan-
tially as herein shown and described with reference to Figures 5 and 6.
4. A compound engine having the h.p. piston above and working through the
1.p. piston and acting on one crank whilst the 1.p. piston acts on a pair of cranks
set opposite to the other crank in which steam is first expanded on the side of the
h.p. piston remote from the cranks, next in the inter-piston space, and finally on
the side of the I.p. piston adjacent to the cranks, whilst during the latter part of
the return stroke the 1.p. piston compresses steam in the inter-piston space or
receiver and the h.p. piston in another receiver in order to keep the bearings in
constant thrust, substantially as herein shown and described with reference to
Figures 1, 2 and 7 to 10.
5. A compound engine having two pistons fixed on the same rod acting upon
a crank opposite the low pressure crank and in which receivers are provided in
connection with the intermediate and low pressure cylinders for the purpose of
keeping the connecting rod and bearings in constant thrust against the crank pins,
substantially as herein shown and described and illustrated particularly with
reference to Figure 4.
6. An engine containing two pistons and receivers for maintaining constant
thrust with the rod of one piston working centrally through the other piston act-
ing on one crank whilst the other piston acts on a pair of cranks on the same
shaft set opposite and one on each side of the other crank in combination with

page_text: a central valve constructed and operating substantially as herein shown and
described in reference to Figures 7 to 10.
7. An engine having a valve with a receiver space in connection with it which
receives a charge of steam at one end of the valve's travel and discharges a portion
of the same into a receiver or part of the engine where the pressure is less than
the initial pressure, substantially as herein shown and for the purpose specified.
8. An engine having a receiver which is connected with the top of the piston
shortly after the steam is cut off and remains connected therewith until near the
top of the return stroke the two sides of the piston being connected together from
the bottom of the upstroke until about mid-stroke after which steam expands
below and is compressed above into the receiver which is disconnected again near
the top of the stroke prior to the next admission of steam, as described in refer-
ence to Figures 11 and 12 and for the purpose specified.
9. A tandem compound engine with a piston or trunk fixed on the piston rod
between the h.p. and 1.p. pistons having steam distribution and means for
maintaining the constant thrust, substantially as set forth with reference to
Figure 13.
10. A compound engine provided with receivers having a h.p. cylinder fixed
concentrically on a 1.p. cylinder and the h.p. piston working on a crank set at a
suitable angle to the 1.p. cranks and having a central valve formed on or
nected to the h.p. piston rod and working in liners, all arranged and operating
substantially as described with reference to Figure 14.
con-
11. The improved construction of balanced engine substantially as herein shown
and described and illustrated by Figure 16.
12. The combination with a single-acting engine having a receiver or receivers
for maintaining the constant thrust, of the valve gear, substantially as described
with particular reference to Figures 1, 2 and and 3.
13 The combination with a compound single-acting engine having the pistons
working opposite and having a receiver or receivers for maintaining the constant
thrust, of the valve gear substantially as described with particular reference to
Figures 1, 2 and 3.
14. The combination with a single acting engine having a receiver or receivers
for maintaining the constant thrust and provided with a central valve, of the
valve gear substantially as described with reference to Figures 7 and 8.
15. The combination with a single-acting engine having a receiver or receivers
for maintaining the constant thrust, of the valve gear described with reference
to Figures 17 and 18.
16. The combination with a single acting engine having a receiver or receivers
for maintaining the constant thrust, of the valve gear described with reference
to Figure 19.
17. The combination with a single-acting engine having a receiver or receivers
for maintaining the constant thrust, of the valve gear described with reference
to Figure 20.
18. The improved device for counteracting the effect of the obliquity of the con-
necting rod substantially as herein shown and described with reference to
Figures 21, 22 and 23.
19. In engines, the improved construction and arrangement illustrated by the
accompanying drawings.