Year: 1895

page_text: Date of Application (in United Kingdom), 24th Dec., 1895
Complete Specification Left, 24th Dec., 1895-Accepted, 18th Apr., 1896
I, JOHN SMITH RAWORTH, of 46 Christchurch Road, Streatham Hill, in the
County of London, 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:-
My invention has reference to the improved construction hereinafter claimed of
steam engines in which two or more cylinders are used in tandem.
In the accompanying drawings,
Fig. 1 shows partly in vertical section on the line A B of Fig. 2, and partly in
elevation, a compound vertical steam engine constructed according to this invention,
and in which two cylinders are arranged tandemwise and steam is admitted
alternately to each cylinder at the inner side of the piston through ports controlled
by cylindrical distributing valves of the Corliss type arranged between the
juxtaposed inner ends of said cylinders, as described in my prior Specification
No. 4442 of 1895.
Fig. 2 shows the engine in elevation, and Fig. 3 is a sectional view at right
angles to Fig. 1.
Figs. 4 and 5 are sections through the valve box on the lines C D and E F
respectively of Fig. 3, the valves and their driving mechanism being omitted.
Referring to Figs. 1 to 3, the bigh pressure steam enters through the end of the
valve chamber d from the inlet branch d* and is admitted at suitable intervals by
the valve g, vibrating on its axis, through the short direct port d to the high
pressure cylinder a, which is surrounded by a live steam jacket al. When the
high pressure piston m arrives at the top of its stroke, it passes a ring of port
holes a, by means of which equilibrium is established between the steam pressures
in the cylinder a and the receiver which is in communication by means of the
ports with a chamber or pocket formed in a partition or valve box arranged
between the adjacent inner ends of the cylinders and in which the valve chambers &
and e are also formed as shown.
The high pressure piston having arrived, as described, at the top of its stroke,
and the high pressure steam port d' having been previously closed, the low
pressure cylindrical valve h will have commenced to open a passage through the
valve chamber e and short direct ports e¹ between the high pressure cylinder a :
and the low pressure cylinder b, and also to open a passage through the said valve
chamber and the ports 1³, e¹ and e², between the receiver and the inner end of each
cylinder, and each of these passages will remain open until the point of cut off is
037

page_text: reached, say one half to three quarters of the stroke, when the passage e² to the
low pressure cylinder will be closed and the steam remaining in the high pressure
cylinder will pass into the receiver through the ports (Figs. 4 and 5) which
remain open to the high pressure cylinder until the valve h closes the port el for
compression.
The low pressure piston n on arriving at the bottom of its stroke passes a ring
of port holes b' which allow the water and steam to pass out into the exhaust
chamber k from which an outlet is provided at 2¹ for the free escape of the said
water and steam.
On the up or return stroke of the low pressure piston n, an outlet for the steam
remaining above the piston is provided through the pipe i by the exhaust cavity
of the valve h covering the two ports e e³.
During the down stroke of the high pressure piston m, steam from the receiver
obtains access to the top side of the said piston. In non-condensing engines this
communication may be constant through holes in the cover at, but in condensing
engines it is better to make it intermittent through the port. holes a³ as shown.
The steam jacket a¹ is supplied with live steam through a small port a
communicating with the valve chamber d, and the condensed water is collected at
each stroke in a small pocket in the low pressure valve h being fed thereto by a
similar port to a² and by the motion of the valve carried round and discharged
through a small port leading into the exhaust cavity e. These ports, and the
corresponding pocket in the valve, are merely drilled holes and are too small to be
visible in the drawings. A relief valve is or may be placed in the head of the
low pressure cylinder to discharge water or excessive steam pressure into the
receiver 1².
The high pressure valve in addition to opening the high pressure port d' at
one end of its travel, is or may be arranged to open, at the other end of its
travel, one or more small ports (Figs. 4 & 5) to the receiver 1, 2, whereby
live steam will be admitted to the latter for the purpose of warming the engine
at starting, but the warming ports are not uncovered at full speed as the governor
will then have reduced the travel of the valve.
The valves 9 and h are driven by spindles after the usual manner employed
with Corliss valves, and on the end of each spindle is fixed an arm or lever i
provided with a pin having a spherical end (shown in Fig 1A) which engages
with a spherical socket or bearing on the end of the corresponding eccentric rod j.
This socket or bearing consists of two cylindrical pads 3 each with a hollow
spherical bearing face, the pads being held and bound together around the
spherical ended pin within a cylindrical box by means of a screw lid or stopper iº,
which not only holds the two pads together but enables any wear to be taken up
with ease and rapidity.
The eccentric rod ; which drives the low pressure valve h, is worked by an
eccentric, fixed on the crank-shaft-and the eccentric rod wbich drives the high
pressure valve g, is worked by an eccentric carried on a movable frame in
combination with centrifugal weights and springs as described in the Specification
of my application for Letters Patent No. 3504 of 1895, for improvements in
automatic expansion governors. But any other suitable form of automatic
expansion governor may be used, or an ordinary throttle valve controlling the
supply of steam to the steam inlet branch d* may be used if required.
The two pistons m and n are both mounted on one rod o which is simply a bolt
binding together the two pistons and the cross head p which are kept apart at their
proper distances by sleeves qg g¹ on the aforesaid bolt. One end of the bolt o is
secured to the crosshead by a cone nut or collar o' made in halves, and at the other
end of the bolt a nut r is screwed down on the high pressure piston. The sleeve
between the high pressure and low pressure pistons, passes through a metallic
packing box s in the partition valve casing or casting between the two cylinders.
The crosshead p is preferably a casting with double sides through which a plain
cylindrical hole is bored for the reception of the crosshead pin p₁ which is or may

page_text: be hollow, in which case the pin is fastened in the crosshead by two cones, one at
each end, which on being drawn together by a bolt expand the ends of the hollow
pin and fix it firmly in the sides of the crosshead. The crosshead guides p³ are
cast in one piece with the hollow truncated cone frame or pillar which supports.
the cylinders f. For small engines this frame or pillar may be cast in one piece,.
but for large engines may be built up in any convenient and suitable manner. This
frame, which is provided with large openings for examination and repair of the-
engine, is closed in by a sheet metal apron t' which retains the oil and returns it
to the crank chamber a, which forms part of the base plate upon which the engine.
is built.
The crankshaft bearings, which are of ordinary construction, are held down by
wedge pieces and tightening screws ³ the heads or nuts on which are outside
the casing so that they can be tightened up without removing the casing. The-
upper wedge piece v slides in horizontal slots cut in the sides of the bearing
seat.
The drip oil from the eccentrics ; is received in a receptacle wo that is in.
connection with the crank chamber x. In this receptacle is or may be arranged a
rotary pump driven by chain or other gear from the crankshaft. The pump takes
oil from the receptacle and delivers it to the bearings and joints of the valve
spindles whence it flows back to the crank pit by way of the crosshead guides p².
and crosshead joint.
The lubrication of the cylinders may be effected by any convenient form of
cylinder lubricator, but I prefer to use one in which the oil vessel is large enough
to hold say a month's supply and which is provided with an automatic shut off
valve which opens when steam is turned on to the engine and closes when steam is
shut off, the oil being delivered drop by drop as the condensed steam displaces
the oil.
Engines of various types, vertical horizontal or inclined, can be constructed with
cylinders arranged in tandem with valves placed between them in the manner
above set forth.
Figs. 6 to 10 inclusive are vertical sections illustrating the cylinder and valve.
arrangements of several constructions.
Fig. 6 shows parts of a simple engine having two single acting high pressure-
pistons m, m' to the inner ends of which steam is alternately admitted from the.
valve chamber d through short direct ports d' d' by the cut off valve 9, the exhaust
valve serving to place each cylinder in turn in communication with the exhaust
pipe i through the valve chamber e. In this case the outer ends of the cylinders a, a¹
are closed so that the same fluid, for example air, remains constantly therein; or
they may have open ends communicating with the exhaust pipe as shown on the
right hand side of Fig. 9. The valve chambers are formed in a partition arranged
between the inner ends of the cylinders as in the arrangement shown in Figs. 1.
to 5 inclusive, but there is no receiver in this arrangement.
Fig. 7 shows parts of the arrangement represented in Figs. 1 to 5 inclusive and
is placed here in juxtaposition to the others for the purpose of facilitating-
comparison.
Fig.
shows parts of a compound engine consisting of two simple engines, of
which the left hand one has two high pressure pistons m m', as in Fig. 6, and
exhausts into the right hand one, which finally exhausts into the pipe i, the two
high pressure cylinders a a¹ being steam jacketted and provided with a receiver 11*
the two portions of which e' are in communication with the exhaust chamber e as shown,.
and the outer ends of the two low pressure cylinders 6 61 being in communication
with the exhaust pipe i like the outer end of the cylinder b in Figs. 1 to 5.
In this arrangement, whilst high pressure steam is being admitted into and is
expanding in cylinder a, that which has already done duty in cylinder a¹ is
permitted by the valve of the high pressure engine to pass partly into the valve
chamber d of the low pressure engine and thence by valve g therein and adjacent
port d³ to the low pressure cylinder 6', and partly to the receiver / 1*, the steam.

page_text: that has already done duty in cylinder b escaping past the valve of the low
pressure engine to the exhaust . Similarly, when high pressure steam is admitted
to the cylinder a', that which has done duty in cylinder a passes partly to the
receiver and partly to the cylinder whilst that in cylinder b¹ will be passing
to the exhaust i.
Fig. 9 shows parts of a triple expansion engine composed of a compound engine
constructed and operating like that shown in Figs. 1 to 5 inclusive, exhausting into
a simple engine like that shown at the right hand side of Fig. 8.
Fig. 10 shows parts of a quadruple expansion engine consisting of two compound
engines each constructed and operating like that shown in Figs. 1 to 5 inclusive,
arranged in series, the several pistons being of gradually increasing size.
Suitably arranged drain pipes such as (Figs. 8 and 10) are provided where
necessary for running off water of condensation.
Having now particularly described and ascertained the nature of the 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 comprising two cylinders arranged tandem-wise, a
receiver, communication between the receiver and the outer end of the high
pressure cylinder, a partition interposed between the two cylinders, a valve chamber
formed in said partition and which is in communication with the supply of high
pressure steam and with the inner end of the high pressure cylinder, a valve
adapted to control said communication, a second valve chamber also formed in said
partition and which has communications between it and the high pressure cylinder,
the low pressure cylinder, the receiver, and the exhaust, and a valve in said last
mentioned valve chamber adapted to place, at the proper time, the high pressure
cylinder in communication with the low pressure cylinder and for the time to place
both the cylinders in communication with the receiver and subsequently to close
the communication between the low pressure cylinder and the receiver and to open
communication between the low pressure cylinder and the exhaust.
2. A compound steam engine comprising two cylinders arranged tandem-wise,
connected pistons, distributing valves located between the adjacent inner ends of
said cylinders and which control ports leading to those ends, a casing surrounding
the high pressure cylinder and adapted to, be placed in communication with the
upper or outer end of the high pressure cylinder, and with the inner ends of both
cylinders, and a second casing into which extends the lower or outer end of the
low pressure cylinder which is perforated for escape of water of condensation, the
said second casing being connected with the exhaust of the low pressure cylinder,
substantially as herein described for the purpose specified.
3. A steam engine constructed arranged and operating substantially as herein-
before described with reference to and shown in Figs. 1 to 5 inclusive of the
drawings annexed.
4. The construction of engines of the kind referred to in accordance with the
several modifications described with reference respectively to and represented in
Fig. 6; in Fig. 8; in Fig. 9 and in Fig. 10 of the drawings annexed.
Dated this 24th day of December 1895.