Improvements in Compound Steam Engines.
Year: 1892

page_text: Date of Application, 27th Apr., 1892
Complete Specification Left, 27th Feb., 1893-Accepted, 1st July, 1893
PROVISIONAL SPECIFICATION.
Improvements in Compound Steam Engines.
1, WALTER CHARLES CHURCH of No. 6 Trinity Square, Brixton, in the
County of Surrey, Engineer, do hereby declare the nature of this invention to be
as follows:-
My invention relates to the construction and arrangement of the cylinders and
slide valves of compound steam engines in such a manner as to utilise the steam
pressure more fully than in ordinary compound engines, for the production of
motive power.
I arrange a high pressure cylinder or a pair of high pressure cylinders by the
side of and parallel to a low pressure cylinder of considerably greater diameter,
and I provide each of the cylinders with a slide valve arranged to have the steam
admitted to its internal cavity and the exhaust in the slide casing. The casing
of the high pressure slide valve communicates directly with a port leading into
the cavity of the low pressure slide valve. The two piston rods, when only one
high pressure cylinder is employed are connected to one crosshead which is linked
by a connecting rod to a crank, the connecting rod being jointed to the crosshead
at a point such that the strains of the two pistons are nearly balanced. When:
there are two high pressure cylinders, the three piston rods are connected.
to one crosshead the middle of which is linked to the crank. The two or the
three slide rods are likewise connected to a single crosshead linked to suitable
eccentrics or other slide motors. From this arrangement it follows that as the
high pressure piston makes its stroke subject to the high pressure of fresh steam
on its one side, the exhaust steam from its other side acts on the low pressure.
piston, and as there is no cushioning of the steam or compressing into a reservoir,
there is not that loss of power which occurs in ordinary compound engines at
the commencement of each stroke. When the cylinders are above the crank,
I prefer to attach to the rod of the low pressure slide valve a piston working in
a cylinder below the valve case, the lower mouth of this cylinder being in com-
munication with the atmosphere. As the pressure in the slide case is considerably
below that of the atmosphere, the excess of pressure below serves to sustain the
weight of the slide valve. This is obviously applicable to the low pressure slide
or piston valves of compound engines generally.
Instead of slide valves working on flat faces, valves of piston form. may be
employed for the one or the other or for both cylinders.
Two or more sets of cylinders such as are above described may be arranged
to work several cranks on one shaft.
Dated this 27th day of Anril 1800
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Compound Steam Engines.
1, WALTER CHARLES CHURCH of No. 6 Trinity Square Brixton in the
County of Surrey 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 :-
My invention relates to the construction and arrangement of compound steam
engines in such a manner as to utilise the steam pressure for the production of
motive power more fully than is the case in ordinary compound engines.
I arrange a high pressure cylinder or a pair of high pressure cylinders by the
Γ

page_text: side or sides of or parallel to, a low pressure cylinder of considerably greater
diameter than that of the high pressure cylinder or cylinders and I provide each
of the cylinders with a slide valve arranged to have the steam admitted to its
internal cavity or cavities and exhaust into the slide valve chest or casing. The
chest or casing of the high pressure slide valve communicates directly with a port
or passage leading into the cavity or cavities of the low pressure slide valve. The
two piston rods, when only one high pressure cylinder is employed, are connected
to one crosshead which is linked by a connecting rod to a crank, the connecting
rod being jointed to the crosshead at a point such that the strains of the two
pistons on the crosshead are nearly balanced. The piston rods may be connected
to the crosshead in such a manner as to allow for expansion of the cylinders so
as to prevent lateral strain in the piston rods. When there are two high pressure
cylinders used with the low pressure cylinder the three piston rods are connected to
one crosshead, the middle of which is linked to the crank.
The two, or the three, slide valve rods are likewise connected to a single
crosshead linked to suitable eccentrics, or other device for operating the valves.
From this arrangement it follows that as the high pressure piston makes its stroke
(or the high pressure pistons make their strokes) subject to the high pressure on its
or their one side of steam from the boiler the exhaust steam from its or their other
side or sides acts on the low pressure piston to move it in the same direction as
that in which the high pressure piston or pistons is or are moving and as there is
no compressing of the steam into a reservoir or receiver there is not that loss of
power which occurs in ordinary compound engines due to the compressing of the
steam into the receiver during the portion of the stroke of the high pressure piston
before the exhaust is closed and also to the increasing compression of steam as the
piston completes its stroke after the exhaust has been closed. When the cylinders
are above the crank and the invention is applied to condensing engines I prefer to
attach to the rod of the low pressure slide valve a piston working in a cylinder
below the valve case the outer end of this cylinder being in communication with
the atmosphere. As the pressure in the valve chest or case is considerably below
that of the atmosphere, the excess of outside pressure serves to sustain the weight
of the slide valve or valves. This it is obvious is also applicable when the
cylinders are below the crank and to the low pressure slide or piston valves of
compound condensing engines generally.
Either slide valves, piston valves or other suitable valves may be employed for
one or the other or for both cylinders.
Two or more sets of cylinders such as are herein described may be arranged to
work several cranks on one shaft.
And in order that my said invention may be fully understood I shall now
proceed more particularly to describe the same and for that purpose shall refer to
the several figures on the annexed sheets of drawings the same letters of reference
indicating corresponding parts in all the figures.
Figure 1 of the accompanying drawings represents in elevation partly in section
a compound engine constructed according to my invention the covers of the valve
boxes or cases being removed.
I have illustrated one high pressure cylinder used in combination with the low
pressure cylinder but as before stated two high pressure cylinders may be used if
desired in which case there will be a communication for steam exhausted from both
high pressure cylinders to the interior of the valve of the low pressure cylinder and
the low pressure cylinder will be of the requisite capacity to receive steam from
both the high pressure cylinders.
Figure 2 is a part plan and part horizontal section taken along the line a b
Figures 1 and 4.
Figure 3 is a vertical section of the high pressure cylinder and its valve chest or
case, the section being taken along the line ed in Figure 2 and Figure 4 is a
vertical section of the low pressure cylinder and its valve box or case the section
being taken along the line ef Figure 2.

page_text: Figure 5 is a longitudinal section of the crosshead to which the piston rods of
the high and low pressure pistons are connected.
Figures 6 and 7 are views of the interiors of the covers of the high and low
pressure valve boxes or cases respectively.
Figure 8 is a view of the back of the high pressure valve with the cap removed.
Figure 9 is a view of the face of the high pressure valve.
Figure 10 is a section of the high pressure valve taken along the line gh
Figure 8; and Figure 11 is a compound section taken along the lines i k―l m in
Figure 8.
Figures 12 and 13 are respectively front and back views of the cap of the high
pressure slide valve.
Figure 14 is an elevation and Figure 15 a transverse section of the spring
packing ring interposed between the cap and back of the high pressure valve.
Figure 16 is a view of the back of the low pressure slide valve with its
cap removed and Figure 17 is a section of the same taken along the line no
Figure 16.
Figure 18 is a compound section taken along the lines p 2 and rs Figure 16.
Figure 19 is a view of the face of the low pressure valve and Figures 20 and 21
are respectively a front and a back view of the cap of the low pressure valve.
Figure 22 is an elevation and Figure 23 a section of the spring packing ring
interposed between the back of the low pressure valve and its cap.
Referring to Figures 1, 2, 3 and 4, 1 is the high pressure cylinder and 2 the
lower pressure cylinder. These cylinders are arranged side by side or parallel to
each other and may be cast together as shewn or they may be each cast separately
and connected together by any suitable means.
The lower pressure cylinder is of such considerably larger area than the high
pressure cylinder as to utilize as far as practicable the pressure of the steam which
passes directly into it from the high pressure cylinder.
For example in the engine illustrated the diameter of the low pressure piston is
four times that of the diameter of the high pressure piston the boiler pressure being
presumed to be 215 lbs. per square inch. But the proportions will of course vary
according to the boiler pressure for which the engine is designed and according
to the class of engine and the purpose for which it is to be used.
The engine or engines making 60 revolutions per minute the steam occupies only
one second in passing through both cylinders to the atmosphere or condenser as
the case may be, and therefore loss by condensation is greatly reduced.
.
3 is the chest or casing containing the high pressure slide valve 4, and 5 is the
chest or casing containing the valve 6 of the lower pressure cylinder. These valve
chests or casings may be cast in one with the cylinders and be provided with
covers 7 and 8 shewn detached in Figures 6 and 7 or they may be cast separately
and connected to the cylinders, in which case the loose covers 7 and 8 may be
dispensed with. The pistons 9 and 10 of the high and the lower pressure cylinder
are connected by their rods 11 and 12 to gudgeons or trunnions 13 and 14 mounted
in a crosshead 15, or the said gudgeons or trunnions may be formed on the piston
rods themselves if desired. The trunnions of the high pressure piston rod is fitted
into blocks 16 which can slide in slots 17 in the crosshead to prevent any undue
lateral strain on the piston rod or rods by the expansion and contraction of the
cylinders. This crosshead may consist of a solid bar having the piston rods and
also the connecting rod connected thereto by any suitable means but I prefer to
form the crosshead of two sides or cheeks 18 as shewn in Figures 1 and 5 connected
together between their opposite ends by bolts 19 and 20 and also at their ends by
slippers 21, 22 which constitute the guiding surfaces to slide in the guides 23, 23*,
distance pieces 24 being interposed between the sides or cheeks 18 to maintain
them at the required distance apart.
The bolt 20 passes through bosses 25 formed on the sides or cheeks 18 of the
crosshead which bosses constitute the journals to which the forked end of the
connecting rod 26 is connected. This bolt 20 may be prolonged in either or both

page_text: directions and be utilized for driving pumps. The position of these journals
with reference to the points of connections of the piston rods of the high and the
lower pressure pistons is arranged according to the difference in the comparative
diameters of the high and lower pressure cylinder and also to the difference of
pressures exerted on the high pressure piston and on the lower pressure piston
so that the pressure on the opposite ends of the crosshead will be equal or
nearly equal.
In practice I prefer to arrange these bosses or journals in such position that
when the crank is at a quarter stroke that is at right angles to the line of motion
of the pistons, and the connecting rod is at its greatest angle, the leverage between
the journals 25 and the connection 14 of the lower pressure piston rod is such as to
counteract the strain thrown by the connecting rod on the slipper 21 against the
guide 23 at that end of the crosshead when the pistons are making their inward
strokes. The slippers 21, 22. are made of suitable length to prevent the crosshead
from jamming between the guides 23, 23*.
The spindles 28 and 29 of the valves 4 and 6 are connected to sleeves or arms 30
formed on the opposite ends of a crosshead 31 shewn detached in Figure 2 which
sleeves or arms are fitted to slide in guides 32 which are shewn in Figures 1, 3 and 4
as being cast on the valve boxes 3 and 5 but which may be attached thereto, or to
any other suitable part of the engine. This crosshead is connected at 33 to the
mechanism by which the valves are worked.
To prevent the distance between the working faces of the guides 23, 23x, from
being affected by the expansion and contraction of the cylinders I connect the said
guides together by tie bolts 34 or, as shewn, I connect the column or frame 35 to
which the guide 23* is attached to a foot 36 to which the framing or column 37
carrying the other guide 23 is attached. The column 35 is provided with a stud 38
which passes through a block 39 which is fitted in a slot 40 formed in a lug or
bracket 41 on the high pressure cylinder which block 39 forms a distance piece on
which a plate or washer 42 is forced by a nut 43 or otherwise (by a cottar for
example) so as to allow freedom for the movement of the lug 41 between the plate
or washer 42 and a flange or collar 44 on the column or frame 35 to allow the
cylinders to expand and contract under changes of temperature without affecting
the position of the guides 23, 23*. When the cylinders 1 and 2 of a condensing
engine are arranged above or below the crank (in the drawings I have shewn them
arranged above the crank) I balance the weight of the slide valve 6 of the low
pressure cylinder by means of a piston 45 fixed on the spindle 29 of the slide
valve 6 and working in a cylinder 46 which may be cast in one with the valve
chest or case 5 as shewn in Fig. 4 or which may be made separate therefrom and
be connected thereto in any suitable manner. One end of this cylinder is open to
the interior of the valve chest whilst the opposite end is open to the atmosphere so
that as the pressure in the valve chest 5 and consequently on the inner face of the
piston 45 is below the atmospheric pressure acting on the outer face of the piston
the excess of the atmospheric pressure serves to sustain the weight of the slide
valve. Steam from the boilers is admitted by the passage 47 Figs. 1 2 and 3 and
enters the cavity 47* in the high pressure valve 4 whilst the exhaust steam from
the valve chest 3 passes by a passage 48 (shewn clearly in Fig. 2) into the cavity
or cavities 49 in the valve 6 of the lower pressure cylinder 2 (see Figs. 4 and also
Figs. 17, 18, 19 hereinafter referred to).
The internal capacity of the valve and cap forms the high pressure steam chest
and the internal area of the cap is greater than the area of the valve face in contact
with the port face of the cylinder so that the pressure tending to keep the valve to
the port face of the cylinder is greater than the pressure tending to force it from
the said part face and thereby its tightness is ensured.
The valve 4 of the high pressure cylinder is preferably of rectangular form on
its working face 50 as shewn in Figs. 8, 9, 10 and 11 and has on its back an
annular projection or rim 51 over which fits a rim 52 of annular form (as shewn in
Fig. 13) on the cap or back plate. The face of this cap or back plate which works

page_text: against the interior of the cover of the valve chest is of rectangular form on the
exterior but has a recess 53 therein communicating by openings or passages 54 with
the cavity or cavities 47* in the valve. In this face of the cap or back plate is an
annular groove 56 with which are connected other grooves 57 arranged at right angles
to the direction of motion of the valve and extending from the annular groove 56 to
the edges of the cap so that as the surface of the cap rubs against the raised
bearing surface 58 on the interior of the valve chest or its cover (Fig. 6) should
any fluid leak past the edge 59 of the bearing surface 59* of the cap it will enter
the annular groove 56 and pass to outside the valve by the grooves 57 without
affecting the balance of pressure. The grooves 56 and 57 also serve to assist the
lubrication of the rubbing surfaces. The surfaces between the grooves serve to
increase the bearing surface of the cap against the surface 58 in the valve chest or
its cover whereby should any of the motive fluid enter between the surface 59* and
the surface 58 the pressure of the fluid in the interior of the valve and cap acting
on the larger diameter or internal annular surface area 52× of the cap will prevent
the cap from being forced from the surface 58. The middle part of the projecting
bearing surface 58 is recessed as shewn at 60 Fig. 6 the edges of this recess being
so shaped that the inner edge 59 of the bearing surface of the cap will, at each
stroke of the valve, overpass the edge of the recess 60 as will also the outer edge
of the face of the cap overpass the outer edges of the projecting surface 58 and thus
the formation of ribs or shoulders by wear on. the rubbing surfaces is prevented.
The contiguous surfaces of the cap and the valve chest or cover are maintained
in contact (when no pressure is admitted to the cavity in the valve) by a spring 61
enclosed in the hollow boss 66 on the underside of the cap which boss enters a
similar hollow boss 65 formed on the back of the valve. Between the top surface
or edge of the annular projection or rim 51 on the back of the valve and the inner
surface of the cap inside the rim 52 is interposed a spring packing ring 62 (shewn
detached in Figs. 14 and 15) held in position by brackets 63 shewn in section in
Figure 11 and in plan in Figure 14. The outer circumference or periphery of this
packing ring is bevelled as shewn in Figures 10, 11 and 15 for the purpose of
reducing the area of the outer diameter of the packing ring to less area than the
inner diameter of the said ring so that the pressure on the interior of the ring
presses the outer circumference into tight contact with the interior surface of the
rim 52 and also so that the pressure on the face of the ring contiguous to the cap
(which face is of greater area than the face next the annular rim 51 on the valve)
will force the ring into tight contact with the top edge of the said rin 51 and
prevent leakage of the pressure thereat. The spring packing ring is divided at
one part in its circumference to admit of its expansion the division being covered
by a piece 64 fixed by one end to the ring on one side of the division but free at
the other end.
The external surface of the hollow boss 66 containing the spring 61 or the
internal surface of the boss 65 is slightly convex or both the exterior of the boss 66
and the interior of the boss 65 may be convex so as to admit of the valve and its
cap moving to accommodate themselves to unparallelism between the port face of
the cylinder and the surface against which the cap works, and also to allow either
end of the valve to be raised from the port face to relieve undue compression which
may take place in the cylinder by the completion of the stroke of the piston
compressing water contained in the cylinder after the exhausting port or ports is or
are closed by the valve.
This undue compression may arise from priming of the boiler or boilers or by
starting the engine with excess of water in the cylinder which would be compressed
by the piston when completing its stroke. The fracturing of the cylinder or the
blowing off of the cylinder cover or covers and damage to the piston or its rod is
thus prevented whilst the ordinary snifting valves employed for this purpose may
be dispensed with.
The cap and balancing mechanism of the low pressure valve are the same in
construction as those of the high pressure valve hereinbefore described as will be

page_text: seen on referring to Figures 16 to 23 the difference being in the dimensions. The
valve is double ported to suit the ports in the port face of the low pressure cylinder
as shewn in Figures 1 and 4. I have marked the corresponding parts in both
valves and their caps with the same numerals.
The internal area of the cap of this low pressure valve with reference to the
area of working surface or surfaces of the valve face should be such that the
pressure acting on the back of the valve tending to keep the valve on the port face
or faces of the cylinder is greater than the pressure tending to force the valve from
the said port face. 69 are the exhaust ports or passages in the valve. Either end
of this valve may be raised from the port face to relieve undue compression which
may take place in the cylinder in the same manner as described with reference to
the high pressure valve.
The engine works as follows:-
The pistons 9 and 10 being at the end of their inward or top stroke and the
valves 4 and 6 just opening to admit steam to the back or top sides of the pistons
as shewn in Figures 3 and 4 and moving in the reverse direction to that of the
pistons at this period of the stroke, live steam admitted at 47 enters the cavity 47*
of the valve 4 and passes by the port or passage 70 to the top or inner end of the
cylinder 1 and acting on the piston 9 drives it towards the opposite or back end of
the cylinder the exhaust steam from the opposite side of the piston passing out of
the cylinder by the port or passage 71 into the valve chest or casing 3 and out
therefrom by the passage 48 into the cavity or cavities 49 of the valve 6 of the
lower pressure cylinder 2. The valve 6 is a double ported valve (as hercinbefore
described) and the ports 72, 72x as shewn are just opening to admit the exhaust
steam passing from the valve chest or casing 3 to the top or back of the piston 10
to drive the piston towards the outer or downward end of the cylinder 2.
As the area of the piston 10 is considerably greater than the area of the high
pressure piston 9 the whole or nearly the whole of the pressure is taken by the
outward or downward movement of the piston 10 from the valve chest or casing 3
passage 47 and the interior cavity of the valve 6 and at the same time the pressure
is removed from the back of the high pressure piston 9 and also from the high
pressure valve rod or spindle 28.
The exhaust steam from the opposite side of the piston 10 passes by the
ports 73 73* into the valve chest or casing 5 and out therefrom to the atmosphere
or to a condenser by the pipe or passage 74. If the exhaust steam from the
casing 5 passes to the atmosphere the pressure on the valve spindle will only
be momentary but if it passes to a condenser the valve spindle will be in a
vacuum. The same operations as those described will take place when the valves
are reversed to admit steam to the opposite sides of the pistons the steam from
the high pressure valve chest 3 passing through the passage 48 as before into
the cavity of the valve 6 and therefrom through the ports 73. 73* into the
cylinder 2 the exhaust steam from this cylinder passing through the ports 72. 72×
into the valve chest 5, and thence through the pipe or passage 74 into the
atmosphere or into a condenser as before.
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 compound steam engine having its high and low pressure cylinders arranged
side by side or parallel to one another, the valve or valves of the high pressure
cylinder or cylinders, having its or their interior cavity or cavities supplied with
live steam and the valve of the low pressure cylinder having its interior cavity or
cavities supplied with exhaust steam direct from the valve chest or chests of the
high pressure cylinder or cylinders without the said exhaust steam passing first
into a reservoir or receiver the low pressure cylinder being of a capacity to utilize
the pressure of the exhaust steam so received from the high pressure cylinder or
cylinders substantially as herein before described and illustrated by the drawings.

page_text: 2. In combination with high pressure and low pressure cylinders and their valves.
arranged and supplied with steam as claimed by the preceding claiming clause of a
crosshead to which both or all of the piston rods of the cylinders are connected, the
said crosshead being connected to one crank, substantially as hereinbefore.
described and illustrated by the example shewn in the accompanying drawings.
3. In combination with high and low pressure cylinders and their valves arranged
and supplied with steam as claimed by the preceding first claiming clause of a
crosshead to which both or all of the piston rods of the cylinders are connected,.
the said crosshead being connected to one crank and another crosshead, to which
both or all of the valve rods are connected so that the valves are operated by one
valve operating device substantially as herein before described and illustrated by.
the example shown in the accompanying drawings.
4. In compound condensing steam engines the combination with the valve of the
low pressure cylinder of a piston working in a cylinder or passage communicating
at one end with the valve chest or casing, and at the other end with the atmosphere.
so as to sustain the weight of the valve or part of the weight of the valve by
atmospheric pressure substantially as hereinbefore described and illustrated by the.
example shewn in Figure 4 of the accompanying drawings.
Dated this 27th day of February 1802
J. H. JOHNSON & Co.,
Agents.