Improvements in Multiple-cylinder Steam Engines.
Year: 1894

page_text: Date of Application, 30th Jan., 1894-Accepted, 1st Sept., 1894
COMPLETE SPECIFICATION.
Improvements in Multiple-cylinder Steam Engines.
I, CHARLES ARTHUR ALLISON, of 52 Chancery Lane, London, in the County
of Middlesex, Patent Agent, do hereby declare the nature of this invention, (which
has been communicated to me from abroad by Edward Robins Grant, of
57 Broadway, City of New York, County and State of New York, United States
of America, Gentleman), 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 multiple-cylinder engines in which the cylinders are
arranged radially about a common crank-shaft, in pairs, with the cylinders in each
pair located diametrically opposite to each other, and in which the pistons are
connected to a common crank on the shaft; and my invention consists, primarily,
in the combination with the cylinder-pistons of each pair thereof, of arms, rigid
on the pistons, respectively, and extending inwardly of the engine and opposedly to
each other, and with the faces of their inward ends abutting and bearing directly
upon the common crank-pin, and a yielding connection between the opposed inward
ends of said arms, in each pair thereof; and, further, in the combination with the
said cylinders and their respective ports, and their pistons provided with the
described rigid arms abutting and bearing directly upon the common crank-pin
and united in pairs at their bearing ends by a yielding connection, of a disk-
valve, fixed on and rotating with the crank-shaft, and governing the lead and
cut-off of steam to said cylinders, successively, and maintaining the exhaust from
each cylinder, successively, open during the entire of the return-stroke of its
piston, and composed of a channelled and apertured disk, working on a circular
valve-seat on the engine-body, and an annulus fitted to the outward face of the
valve-disk, together with set-screws working in the wall of the valve-chamber and
impinging upon the outward face of said annulus, as described.
Figure 1 is a side-elevation of the engine;
Figure 2 is a plan of the same;
Figure 3 is a vertical section on line a, a, of Figure 2
Figure 4 is a similar section on line y, y, of Figure 2;
Figures 5 and 6 are face or plan views of the disk-valve and its holding
annulus; and
Figure 7 is an enlarged view, in detail, of devices constituting one feature of the
invention.
A, A1, A2, A3 are the multiple cylinders, usually four in number, arranged
radially about a crank-shaft B, and located, in pairs, with the cylinders of each
pair diametrically opposite to each other, and the two pairs at right angles to
each other. The several cylinders open at their inward ends into the chamber B',
upon one side of which is formed the circular valve-seat B². The shaft B has
bearing in the heads 6 and 6. The single stuffing-box required in this engine is
at 62, the opposite side of the engine being closed by the interiorally recessed
annular head B and forming the valve-chamber.
C, C1, C2, C3, are the several pistons in the respective cylinders, and the pistons
are single-acting. Each piston has a rigid arm extending through the open,
inward end of its cylinder, and said arms e, of the opposed pistons of each pair of
cylinders, reach to opposite sides of the shaft-crank b³
The cylinders are furnished with the customary ports, and these ports are
governed in the lead and cut-off, and the exhaust of steam, to and from the several
cylinders, by a disk-valve D which is keyed to the shaft B.
I construct and arrange the pistons in each of the pairs thereof separate from
the opposite piston of the pair, and I cause the extended arm c of each piston to

page_text: abut directly upon the crank-pin. When the engine is in operation, and during
the working-stroke of each piston, inwardly of the engine, the steam-pressure
behind the piston will hold the end-face of the arm c to contact with the crank-pin,
and, during each half revolution of the crank, caused by the "push" upon the pin
by the arm, the pin will traverse said end-face of the arm; while the return-stroke of
each piston will be effected by the "push" of the pin, during each other half of
its revolution, upon said end-face of the arm, the pin reversely traversing said
face during such portion of its revolution. As the pistons may, owing to
extraneous causes, when the engine at rest, assume, or be given, such positions
in their respective cylinders as would remove the end-face of a piston-arm from
contact with the crank-pin, it is desirable to establish such connection between the
opposed ends of the arms of each pair of pistons, that the pistons and their arms,
in each pair, will, at all times, preserve their proper positions relatively to their
mates in each pair, and to the crank-pin. For this purpose I make a yielding
connection between the opposed ends of the piston-arms of each pair thereof;
and this may be done by springs reaching from the side-edges of one to the
other of the mates of arms, and adjustably attached thereto by nuts, as shown
in Figure 7. Any other means for giving this yielding connection between the
opposed arm-ends may be employed. The yielding connection will hold the pistons
and arms in proper position, and there will be no close or confined bearing at the
connections of the arms with the crank-pin, and friction will thus be reduced to a
tninimum.
It is desirable to attach bearing-plates to the ends of the arms c, as by
bolts c; and these plates may be of hardened steel, thus withstanding wear;
while the springs may pass through ends c' of said plates, as shown in Figure 7.
Any wear at the bearing-plates and crank-pin will be compensated by said
springs.
Another feature of this invention, and one which enables the described engine
to be operated at high-speed, consists in the rotary disk-valve D, whereby I
provide an inlet-port d in the valve which may be of such length or duration,
during the working-stroke of each piston, as to cut-off at any point in the stroke;
and to provide an exhaust-port in the valve, of such length as to have it
remain fully open during the entire return-stroke of each piston; and I make this
valve a balanced-valve, whereby high speed is attainable. To balance the
valve D I desirably provide the lateral steam apertures d' through the valve-disk;
and the annulus D2 which fits to the perimeter of the valve on the outer side,
and between which and the valve-scat the valve rotates. I also preferably
provide set-screws d³, working in threaded apertures in the head B2, and projecting
to and bearing upon the outer face of the annulus D2, whereby the annulus and the
It will be
valve may be adjusted relatively to each other and to the seat.
understood that the exhaust from the cylinders passes through the valve and its
seat into the chamber B', and thence out of the chamber, as is frequently done in
engines of this class.
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. In a multiple-cylinder engine in which the cylinders are arranged radially
about a common crank-shaft, in pairs, with the cylinders of each pair diametrically
opposite to each other, the combination with the cylinder-pistons of each pair, of
arms, rigid on the pistons, respectively, and extending inwardly and opposedly to
each other and with the faces of their inward ends abutting and bearing directly
upon the common crank-pin, and a loose or yielding connection between the
opposed inward ends of said arms, as described.
2. In a multiple-cylinder engine in which the cylinders are arranged radially
about a common crank-shaft, in pairs, with the cylinders of each pair diametrically
opposite to each other, the combination with the cylinder-pistons, of each pair, of

page_text: arms, rigid on the pistons, respectively, and extending inwardly and opposedly to
each other toward the cominon crank-pin, and bearing-plates attached to the inward
ends of said arms and abutting, respectively, directly upon said crank-pin, together
with a loose or yielding connection between said bearing-plates on each pair of
arms, as described.
3. In a multiple-cylinder engine having cylinders arranged radially about a
common crank-shaft, in pairs, with the cylinders of each pair diametrically opposite
to each other, and with the cylinder-pistons of each pair thereof provided, respec-
tively, with arms, rigid on the pistons, extending inwardly to and abutting at the
faces of their inward ends directly upon the common crank-pin, and a loose or
yielding connection uniting the opposed inward ends of the arms of each pair of
pistons; the combination with said pistons and their cylinders and the ports thereof,
of a valve, composed of a channelled and apertured disk fixed on and rotating with
the crank-shaft, a circular valve-seat on the engine-body to which said disk-valve
works, and an annulus resting to the outward face of said valve, together with set-
screws through the wall of the valve-chamber and impinging upon the outward face
of said annulus, as described.
Dated this 30th day of January 1894.
ALLISON BROS.,
Agents for the Applicant.