IMPROVEMENTS IN STEAM ENGINES
Year: 1883

page_text: LETTERS PATENT to Alexander Melville Clark of the firm of A. M and
W Clark of 53 Chancery Lane in the County of Middlesex Fellow of the
Institute of Patent Agents for an Invention of IMPROVEMENTS IN STEAM
ENGINES communicated to him from abroad by Anton Eberhart, of the City
and County of Philadelphia and State of Pennsylvania, United States of
America
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark at
the Office of the Commissioners of Patents on the 15th November 1883.
ALEXANDER MELVILLE CLARK of the firm of A. M. and W. Clark of 53 Chancery
Lane in the County of Middlesex, Fellow of the Institute of Patent Agents
"IMPROVEMENTS IN STEAM ENGINES" [communicated to him from abroad by
Anton Eberhart, of the City and County of Philadelphia and State of Pennsylvania,
United States of America]
The object of this Invention is to promote efficiency and economy in the use of
steam,
The Invention consists in a steam engine constructed with two cylinders curved
to the arc of a circle, and having two pistons in each cylinder said pistons being
coupled in pairs (ie one piston of one cylinder with one piston of the other cylinder)
by curved piston rods the cylinders and piston rods together forming a complete
circle. The piston rods are respectively connected by radius arms with sliding
cross heads which are connected by connecting rods with their appropriate crank
pins. Four valves control the inlet and outlet ports of the two curved cylinders;
they are connected in pairs by valve rods which are geared with each other and
with the driving shaft.
The cylinders are each a little less than a quarter of a circle in length and are
placed directly opposite each other. They are open at both ends and have
admission and exhaust ports respectively at the centres of their upper and lower
sides.
The two pistons at the adjacent ends of the two cylinders being connected by
curved piston rods as above mentioned the two pistons of the same cylinder will

page_text: always move in opposite directions those of the one cylinder moving outwards
when those of the other are moving inwards and vice versa.
To the centres of the curved piston rods are bolted the outer ends of two radial
arms whose inner ends are halved together and work upon a common centre pin
concentric to the circle formed by the cylinders and piston rods. These radial arms
have holes in them at about the middle of their length to receive pivots whose
upper parts are squared and pass through transverse slots at the middle of the slides
or cross heads whereby the alternate circular motion of the piston rods and radial
arms will be converted into rectilinear reciprocating motion of the cross heads
The sides of the said slots are faced with bearing plates which are adjusted by
set screws to take up wear.
The ends of the cross heads slide in suitable bearings which are also provided
with adjustable friction plates. The cross heads have each an outwardly projecting
arm which is coupled by a connecting rod with a crank pin on the driving shaft
the two cranks being in line with one another.
The steam valves are rotary plugs or cocks received in seats on the steam. pipes
leading to the two cylinders the thoroughfares or ports of the two valves or cocks
being at right angles to each other to admit steam alternately to the two cylinders
or twice to each cylinder during each revolution of the valves. These valves are
upon a common spindle which is driven by bevel gear from the engineshaft. The
exhaust valves are similar and their spindle is geared with the steam valve spindle
and the two sets of valves rotate at equal speed. The ports or thoroughfares of
the exhaust valves are at right angles with one another and with the ports of the
corresponding steam valves so that as the steam valve of one cylinder is opened
the exhaust valve of the said cylinder will be closed, and the other cylinder will
have its steam valve closed and its exhaust valve opened. Thus as steam is
re-admitted into one cylinder it will be exhausted from the other.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Alexander Melville Clark in the Patent Office on the 13th May
1884.
ALEXANDER MELVILLE CLARK of the firm of A. M. and W. Clark of 53 Chancery
Lane, in the County of Middlesex, Fellow of the Institute of Patent Agents
IMPROVEMENTS IN STEAM ENGINES (a communication to me from abroad by
Anton Eberhart, of the City and County of Philadelphia and State of Pennsylvania
United States of America
The object of this invention is to promote efficiency and economy in the use of
steam. The invention consists in a steam engine constructed with two cylinders
curved to the arc of a circle, and having two pistons in each cylinder said pistons
being coupled in pairs (ie, one piston of one cylinder with one piston of the other
cylinder) by curved piston rods connected by radius arms with sliding cross heads
which are coupled by connecting rods with their appropriate crank pins. Four
valves control the inlet and outlet ports of the two curved cylinders; they are
connected in pairs by valve rods, geared with each other and with the driving shaft
whereby the said valves are opened and closed automatically and at the proper
times, as will be hereinafter fully described.
Figure 1 of the drawings is a plan view of the engine, parts being broken away.
Figure 2 is a sectional side elevation of the same taken through the broken
line xxxx figure 1. Figure 3 is a plan view of a part of one of the cross heads.
Figure 4 is a sectional elevation of the engine taken through the broken line y Y Y
figure 1. Figure 5 is a horizontal section through the steam cylinders showing the
pistons, piston rods and piston rod levers, in plan view. Similar letters of reference
indicate corresponding parts in all the figures.
A. A¹ are two steam cylinders which are made in the form of arcs of circles, and
of a length a little less than a quarter of a circle. They are placed directly opposite
each other and in the circumference of the circle of which they form arcs, as shown
in figures 1 and 5 and are mounted upon standards or other supports B, B¹ secured
to the bed plate C of the machine. These cylinders A A¹ are open at both ends
and have admission ports D D¹ and exhaust ports E E¹ at the centres of their
upper and lower sides respectively the admission ports D D¹ being connected
respectively with the branches F F of the steam pipe G and the exhaust ports E E¹
with the outlet steam pipes H H. II' are the two pistons in each of the two
cylinders the two adjacent pistons of the two cylinders being connected by piston -
rods J J which are curved to and complete the circle of which the cylinders form
a part so that the pistons of the same cylinder will always move in opposite direc-
tions and those of the one cylinder will always.move outwards when those of the
other cylinder are moving inwards. To the centres of the curved piston rods J J
are bolted the outer ends of two radial arms K K¹ whose inner ends are halved
together and work upon a common centre bolt L formed upon or attached to the
upper end of the standard M, which is secured to the base C in the centre of the
circle of which the cylinders A A¹form a part. The middle parts of the arms KK'
are thickened and have holes formed through them to receive the pivots N N¹
which are secured in place by washers and nuts applied to their lower ends.
The upper parts of the pivots N N₁ are squared, pass through slots in the
lugs O O at the middle of the slides or cross heads P P and have washers and
nuts applied to their upper ends whereby the cross heads P P¹ will be moved back
F

page_text: and forth in straight lines by the movements of the radial arms K K¹ through the
arcs of circles. The sides of the slots in the lugs 00' are faced with bearing
plates to lessen the friction and which are adjusted by set screws R R to take
up wear.
The ends of the cross heads P P¹ slide in bearings S S¹ attached to the ends of
the cylinders A A' or other suitable supports and which are also provided with
friction plates adjustable by means of set screws m. TT are arms projecting
outwards from the middle of the slides to which are pivoted the ends of the
connecting rods U, U₁, whose other ends are pivoted to crank pins V, VI, attached
to the fly wheels W, W', secured to the shaft X which revolves in bearings in the
supports Y, attached to the base C.
The fly wheels W, W¹, may be made with flat faces to receive belts for giving
motion to the machinery to be driven or power may be taken from the engine by
means of a pulley or gear wheel attached to the shaft X as indicated in dotted lines
in figure 1. Upon the shaft X is keyed a small bevelled toothed wheel Z which
gears with a larger gear wheel a keyed to the outer end of the valve rod b. The
inner end of the valve rod b is connected with the inner end of the valve rod b¹ by
sleeves c set screws d and a connecting rod e or other suitable couplings. Upon
the parts of the valve rods 6 b¹ that pass through the steam inlet pipes F F are
formed, or to them are attached valve plugs ff' which work in seats in the pipes.
The ports of these plugs are at right angles with each other, as shown in figure 2,
so that steam will be admitted into the cylinders A A' alternately or twice to each
cylinder during each revolution of the valve rods b b¹. To the outer part of the
valve rod b¹ is attached a toothed wheel g which gears with a wheel g¹ attached to
the outer part of the valve rod h. The gear wheels g g¹ are of equal size so that the
two sets of valve rods will be revolved at equal speed. The inner end of the valve
rod h is connected by a sleeve ȧ and set screws j with the inner end of the
corresponding valve rod h¹.
Upon the parts of the valve rods h h¹ that pass through the exhaust pipes H H¹
are formed or to them are attached valve plugs kk' the ports of which are at right
angles with each other and with the ports of the corresponding steam valve
plugs ff as shown in figure 2. With this arrangement as the steam valve of one
cylinder is opened the exhaust valve of the said cylinder will be closed, and the
other cylinder will have its steam valve closed and its exhaust valve opened. Thus
as steam is admitted into one cylinder it will be exhausted from the other.
Having described, the nature of the said invention, and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
herein before in part recited Letters Patent is:-
1st A steam engine constructed substantially as herein shown and described and
consisting of two cylinders curved upon the arc of a circle, four pistons connected
in pairs by curved piston rods connected by radius arms with slotted cross heads
provided with arms coupled by connecting rods with crank pins on the fly wheels
of the driving shaft, as set forth.
2nd In a steam engine the combination with the curved cylinders A, A¹, the
curved piston rods J, J', and the connecting rods U, U₁ connected with the driving
shaft X, by the crank pins V, V₁, and fly wheels W, W¹, of the radius arms K, K₁,
and the cross heads P, P¹, having slotted lugs 0, 0, and pivot arms T, T', substan-
tially as herein shown and described whereby the reciprocating motion of the piston
rods is changed into a rotary motion as set forth.
3rd In a steam engine the combination, with the curved cylinders A, A¹, the
steam ports D, D' the exhaust ports E E¹, and the driving shaft ✗, of the
valves f, f¹ k, k', the valve rods b, b', h, h¹ and the gear wheels g, g¹, a, Z, substan-
tially as herein shown and described, whereby the valves will be opened and closed
automatically and at the proper times, as set forth.
4th The cross heads P P¹ having slotted lugs O, O¹, on the inner sides of their
centres in combination with the pivots N, N₁ squared at their upper ends and

page_text: passing through said slots and the levers K, K¹ provided with middle bearings
for said pivots whereby the cross heads may always move in straight lines as
described.
In witness whereof I the said Alexander Melville Clark, have hereunto set my
hand and seal this thirtieth day of April A.D. 1884.