Year: 1888

page_text: I, GEORGE JOHNSTON, of Mosesfield, Springburn, in the County of Lanark, North
Britain, Engineer, do hereby declare the nature of this Invention to be as follows,
that is to say
My said Invention has for its object the construction of an improved, simple, and
economical motor to work with combustible gas or vapor
In carrying out my Invention I employ a cylinder which is open at both ends
and has fitted to work in it two pistons, hereinafter termed the quick and slow
pistons Two crank shafts are provided and are geared together so that one which
is connected to the quick piston makes twice as many revolutions as the other which
is connected to the slow piston. The strokes of the two pistons may be in various
ratios, but I prefer them to be equal; and I prefer to arrange the relative positions
of the cranks so that the slow piston completes its inward movement a little after
the quick piston has begun one of its outward movements. Just before the slow
piston completes its inward movement the two pistons are in contact or nearly so,
but the rapid motion of the quick piston causes a separation even before the slow
piston begins to move outwards. At this stage the explosive mixture is admitted
through a suitable valve The space between the pistons increases to some extent
but the return inwards of the quick piston diminishes the space and causes compression
of the explosive mixture. The space between the pistons afterwards enlarges again
and rapidly acquires its greatest extent when both pistons are at or near the outer
ends of their strokes. At the beginning of the enlargement of the space the
explosive mixture is ignited by means of any suitable one of the various devices now
in use in gas motors. As soon as the space begins to diminish again an exhaust
port is opened, and as the pistons approach very near each other the gaseous
products are expelled in a practically complete manner The actions herein before
described constitute the cycle of the motor and are repeated once for every revo-
lution of the crank or cranks to which the slow piston is connected.
Dated this Fifth JT 1000
EDMUND HUNT,
Applicant's Agent.

page_text: Improvements in Motors to Work with Combustible Gas or
Vapor.
I, GEORGE JOHNSTON, of Mosesfield, Springburn, in the County of Lanark,
North Britain, Engineer, do hereby declare the nature of this invention and in
what manner the same 19 to be performed, to be particularly described and
ascertained in and by the following statement, that is to say :-
My said Invention has for its object the construction of an improved, simple,
and economical motor to work with combustible gas or vapor.
In carrying out my Invention according to one modification of which the main
parts are shown on an accompanying sheet of explanatory drawings, figures, 1, and 2,
thereof being a sectional side elevation and a sectional plan, 1 employ a cylinder, A,
which is open at both ends and has fitted to work in it two pistons, B, C, hereinafter
termed the quick and slow pistons. Two crank shatts, D, E, are provided and are
geared together by spurwheels, F, G, so that one, D, which is connected to the quick
piston; B, makes twice as many revolutions as the other, E, which is connected to the
slow piston, C The quick piston, B, 18 connected to its crank by a rod, B 1, in the
ordinary way, the slow piston U, being connected by a rod, C1, to a lever, C2,
which is connected by a rod, C3, to the crank of the slow shaft, E. The strokes
of the two pistons may be in various ratios but I now prefer the stroke of the quick
piston, B, to be a little longer than that of the slow pistou, C; and 1 prefer to
airange the relative positions of the cranks so that the slow piston, C, completes its
inward movement a little after the quick piston, B, has begun one of its outward
movements Figure, 3, is a diagram which shows the positions of the two pistons
during one complete cycle of movements The diagram is divided by horizontal lines
into spaces each of which represents 4th of a revolution of the slow shaft, E, and
the curves, b-b, c-c, mark in each space the positions of the pistons, B, C A little
before the slow piston, C, completes its inward movement the two pistons are nearly in
contact as at, but the rapid motion of the quick piston, B, causes a separation even
before the slow piston begins to move outwards. At this stage the explosive mixture
is admitted through a suitable valve and port, H. The space between the pistons
increases to some extent but the return inwards of the quick piston, B, diminishes
the space and causes compression of the explosive mixture. The space between the
pistous afterwards enlarges again and rapidly acquires its greatest extent when both
pistons are at or near the outer ends of their strokes At, y, the beginning of the
enlargement of the space the explosive mixture is ignited through a port, J, by means
of any suitable one of the various devices now in use in gas motors. As soon as the
space begins to diminish again an exhaust port, K, is opened, and as the pistons
approach very near each other the gaseous products are expelled in a practically
complete manner. The actions hereinbefore described constitute the cycle of the
motor and are repeated once for every revolution of the crank or cranks to which

page_text: the slow piston, C, is connected. During the part of the cycle as shown in the
diagram from z, to a, the explosive gaseous mixture is drawn into the cylinder; the
mixture is compressed from a to y, and is ignited at y; expansion takes place from
y to w, and the used gases are expelled from w to z.
The admission, ignition, and exhaust valves may be of any suitable kind used in
gas motors, and may be moved from the slow shaft, E, by means of eccentrics or
cams.
The movements of the pistons, B, C, which take place with the arrangement of
two shafts, D, E, geared together as herein before described, are obtainable in a
mechanically equivalent manner with a single rotating shaft, and an arrangement of
levers and connecting rods, of which a diagram is shown in figure, 4. The crank of
the shaft, E, connected to the slow piston, C, is also connected by a rod, L, to one
arm, M, of a two-armed lever, M N; and the other arm, N, is connected by a rod, P,
to one arm, Q, of a two-armed lever, QR, the other arm, R, of which is connected
by a rod, S, to the quick piston, B. The lever arms, N, and Q, are relatively so placed
as regards their centres and the angles through which they move as that the latter
makes two reciprocations for every one made by the former; and as a consequence
the piston, B, makes two strokes for every stroke of the piston, C, precisely as in
the arrangement shown in figures, 1, and 2.
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 :--
In a motor to work with combustible gas or vapor, the combination of a cylinder
with two pistons connected externally in a manner to cause one piston to make two
strokes for every stroke of the other piston, the parts being arranged and operating
substantially as hereinbefore described.
Dated this Fourth day of March 1889.
EDMUND HUNT,
Applicant's Agent.