Improvements in Double-cylinder Steam Engines.
Year: 1890

page_text: Date of Application, 16th Sept., 1890-Accepted. 13th Dec., 1890
COMPLETE SPECIFICATION.
Improvements in Double-cylinder Steam Engines.
I, WILLIAM DAVIS HOOKER, Manufacturer, of Chicago, in the County of Cook,
and State of Illinois, United States of America, 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 :-
The present invention relates to double cylinder steam engines in which the
valves and ports of both engines are so constructed, and said valves are so operated
by mechanism which derives its notion from the piston of one of said engines,
that one engine will commence its stroke before the stroke of the other engine is
completed.
The object of the said invention is to so improve the construction of such engines
that both shall operate precisely alike, to the end that the operation of the pumps
shall be alike, and consequently smooth and noiseless, even when running at the
highest attainable speed.
The invention consists in certain features of novelty that are particularly pointed
out in the claims hereinafter, an engine embodying said invention being first fully
described with reference to the accompanying drawings, which form a part of this
Specification, and of which :-
:-
Figure 1 is a sectional elevation of the improved engine, the near steam cylinder,
its valves, valve chesis, and other accessories being shown in vertical longitudinal
section, while the yoke, the valve mechanism and its accessories are shown in side
elevation.
Figure 2 is a vertical transverse section thereof on the line 2-2, Figure 1.
Figure 3 is a vertical transverse section of the valve actuating mechanism on the
line 3-3, Figure 1.
Figure 4 is a plan view of the improved engine.
Figure 5 is a sectional elevation of the valve mechanism of the auxiliary engine.
Figure 6 is a sectional elevation of the valve mechanism of the main engine.
Figure 7 is an elevation of the parts hereinafter described.
Figure 8 is a plan view, partly in section, showing the relative positions of the
pistons.
A represents a steam cylinder, B a piston therein, C the piston rod, and D the
valve for controlling the admission of steam to, and its exhaust from, the cylinder.
This valve is contained within a suitable chest E, and is itself actuated by steam,
which is admitted to, and exhausted from, the opposite ends of said chest under the
control of a supplemental valve F contained in a suitable chest G, supplied with steam
through a duct ġ.
So far as the present invention is concerned, these valves may be of any desired
construction and the ports may be arranged in a desired manner, so long as the con-
struction and arrangement are such that steam will be admitted to one cylinder so
that the piston commences its stroke when the piston of the other cylinder is at or
near the centre of its stroke, so that one engine shall lag about half a stroke behind
the other, as presently described. The construction and arrangement shown in the
drawing are so very simple that very little description of them is necessary, as they
will be readily understood from the drawing by those skilled in the art. The supple-.
mental valve F is of the "D" type. It is of such length, and the ports, f, through
which steam is supplied to and exhausted from the opposite ends of the valve chest E,
open into its chest G at such distances apart, that when it is at the centre of its
stroke, both of said ports are closed, but the instant it is moved beyond its central
position, one or the other of said ports is uncovered, thereby admitting steam to one
end and exhausting it from the other end of the cylinder E, shifting the valve D, and

page_text: permitting steam to enter one and exhaust from the other end of the cylinder A for
producing the stroke of the piston B.
His a yoke, from the top side of which rises a standard I having at its upper end
a bearing i, in which is journalled a horizontal shaft J. K (Figure 6) is a lever,
whose lower end is loosely fulcrumed upon the shaft J, and whose upper end is
bifurcated and embraces one end of a short link l, to which it is pivottally connected.
This link forms a part of a valve rod L which enters chest G through a suitable
stuffing box, and is connected to the valve F for operating it. The adjacent part 1x of
this valve rod has its end screw threaded and passed loosely through a perforation in
the end of the link l. A pair of nuts situated upon opposite sides of the end of
the link serve to hold the parts and 1x together, and enable their adjustment
longitudinally with respect to each other for lengthening or shortening the valve
rod L.
M is a lug, the contracted stem of which passes through a longitudinal slot through
the lever K, and is screw-threaded for the reception of the nut m, whereby said lug
may be adjusted toward or from the centre of oscillation of said lever. N is a plate
cast in one with, or secured to, the end of the shaft J and forming a T-head. Upon
the side of this plate, adjacent to the shaft are a pair of lugs or tappets n, n*, between
which the lug M projects. Against the other side of this plate is secured by bolts, a
second plate O of corresponding shape, one or both of said plates being grooved to
form a bearing in which a lever P fits snugly, so as to be capable of only an end wise
movement therein. Qis a two-part block, which is secured to the piston rod C and
has in one of its sides, a vertical under-cut groove q, and R is a bolt, the head of
which fits in said groove while its stem passes through a wrist pin r and receives a
nut, whereby said wrist pin may be adjusted transversely with respect to the piston
rod, or in other words, toward or from the rock shaft J. The wrist-pin fits an eye at
the lower end of the lever P, the latter being held in place thereon by a washer
beneath the nut or bolt R.
This completes the description of the various parts of what is called in this
Specification (for the sake of convenience) the "main" engine, the operation of
which will be described presently.
The auxiliary engine is situated beside the main engine and may be constructed as
follows. A is a cylinder, in which works a piston B¹ having a rod C. D' is a
steam actuated valve for controlling the admission of steam to, and its exhaust from
the cylinder A', and E' is the chest in which said valve is contained. Steam for
actuating the valve D' is admitted to and exhausted from the ends of the chest E¹
through ports f f under the control of a supplemental valve F1 situated in a suitable
chest G', to which steam is supplied by a duct g'. The valve F¹ is fixed to one end
of a valve rod L' formed of two parts 11, 1×1 secured together by a pair of nuts, so as
to be longitudinally adjustable. The other end of the valve rod is secured by a pivot
pin to the bifurcated extremity of the vertical arm t of a part T hereinafter called a
slide. This slide T is of L shape, and at its angle is secured by a pivot pin to the
upper extremity of a short arm U which is fixed rigidly to the shaft
screw u. The arm of the slide T is horizontal, and at its extremity fits loosely into
a sleeve or socket V¹ secured to the end of the valve chest E¹. H' is a yoke to which
is secured a standard I' having a bearing i', in which the shaft J is journalled.
by a set
Similar parts in the two engines are indicated by similar letters of reference, the
prime (1) mark being added to distinguish the parts of the auxiliary engine. As the
piston rod C moves back and forth it carries with it the lower end of the lever P, and
thereby causes the shaft J to rock or oscillate about its centre. As the lever K is
loose upon the shaft J it will not be affected by the movement of said shaft until one
or other of the tappets (n or n*) comes in contact with the lug M, and this does not
take place until the main engine is about to complete its stroke in one direction or the
other. As shown in the drawing, the piston of the main engine is moving to the
right. When it is about to complete this stroke, the tappet n will come in contact
with the lug M and throw the lever K to the left, which shifts the valve F to the left,
thereby permitting steam to enter the right hand end of valve chest E and force

page_text: valve D to the left, thereby permitting steam to exhaust from the left hand end and
enter the right hand end of cylinder A, forcing the piston B to the left.
When it is
about to complete this stroke to the left, the tappet n* comes in contact with lug M
and operations the reverse of the foregoing take place.
Upon the top side of the standard I are cast or secured a pair of lugs S, between
which the nut m, or the stem of the lug M projects, thereby forming a stop for
limiting the movement of the lever K and preventing the valve F from being
thrown too far when the engine is running at high speed.
Since the arm U is rigidly fixed to the shaft J and the connections between it
and the supplemental valve F1 of the auxiliary engine do not permit of any lost
motion, it follows that the said supplemental valve F¹ must move in unison with
the piston rod C of the main engine, and that when said engine is at the centre of
its stroke, the said valve will be at the centre of its stroke. This valve is so
constructed (in the instance given in the drawing it is exactly like the valve F
of the main engine) that when it is at the centre of its stroke, the ports f¹, f,
through which steam passes to the respective ends of the valve chest E, are both
closed, and the instant it passes the centre, one or the other of the said ports is
opened. As the parts are shown in the drawing, the main engine is at the centre
of its stroke in the direction of the arrow (to the right) and the supplemental
valve F of the auxiliary engine is in the centre of its stroke in the opposite
direction, (to the left) the piston of the auxiliary engine having completed its
stroke to the right. As soon as these parts pass these positions, the valve F¹
will uncover the port that admits steam to the right hand end of the chest E',
whereby the valve D¹ will be forced to the left, uncovering the port through which the
steam is admitted to the right hand end of the cylinder A. Thus the stroke of
the auxiliary engine is reversed when the main engine is at or near the centre of its
stroke, and the valves of both engines are controlled by the main engine. The term
"main engine" is employed in this Specification to designate the one of the engines
which controls the operation of the other. Either of the two engines may be used as
the main engine. The engine above described as the auxiliary engine may be made
the main engine by turning the shaft J end for end, connecting the lever P to the
piston rod C, and transposing parts K and T-U.
Steam is supplied to the main and auxiliary engines through separate pipes ✗
and X', having valves and a respectively. While both engines are running, by
closing the valve a steam will be shut off from the auxiliary engine and said engine
will stop, while the main engine will run on alone, as a single engine.
Since the supplemental valve of the auxiliary engine, and the piston of the main
engine, move synchronously, the mechanism connecting them must be such as to
materially reduce the extent of the movement, so as to move the supplemental valve
the proper stroke. It is to this end that the arm U is made so short. The slide T
neither augments nor reduces the extent of the movement, it being an expedient for
connecting the end of the arm U with the end of the valve rod L, the latter being
considerably above the former.
On the other hand, since the piston of the main engine moves nearly its whole
stroke without affecting the supplemental valve of the main engine, and said valve
must be shifted while the said piston is completing the last inch or so of its stroke, it
is manifest that its movement must be a quick one. This quick movement for this
valve, as well as the slow movement for the valve F¹, is also derived from the rock
shaft J. It is accomplished by making the lever K of sufficient length and connecting
the valve rod to it at a sufficient distance from its fulcrum. This movement may be
regulated by adjusting the lug M (which is the point at which the power is applied)
toward or from the fulcrum, thereby increasing or decreasing the length of the "load
arm of the lever.
"
The amplitude of the movement of the rock shaft itself may be regulated by.
moving the block r toward it or from it, accordingly as it is desired to increase or
decrease it.

page_text: I desire to have it understood that my invention is not limited to the precise
construction of valve mechanism shown and described, as said mechanism may be
varied within wide limits without departing from the spirit, or sacrificing the
advantages, of my invention.
The ultimate object of the present invention is to produce a double cylinder engine
whose action shall be uniform, steady, and constant. In order to accomplish this
result it is essential that the operations of the two pistons being precisely alike, and
that each shall commence its stroke before the stroke of the other is completed. In
order that the pistons shall operate alike, it is not only necessary that they be the
same size, but it is also necessary that the steam by which they are driven be admitted
to and exhausted from the cylinders of both, under precisely similar conditions.
This latter can be accomplished only by providing both engines with valves of similar
construction under the control of mechanism which shall insure their similar
operation.
A duplex engine in which the main valve of the auxiliary engine is driven by
direct connections with the piston rod of the main engine without the intervention of
a supplemental valve is not the equivalent of my invention.
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. The combination with the main and auxiliary engines, both having steam
actuated main valves and supplemental valves for controlling said inain valves, of
connections between the supplemental valves of both engines and the piston rod of
the main engine, whereby said valves are moved, the ports and valves of both engines
being so constructed and arranged that each engine shall commence its stroke before
the stroke of the other engine is completed, substantially as set forth.
2. The combination with a supplemental-valved main engine and a supplemental
valved auxiliary engine, of connections between the supplemental valves of both
engines and the piston rod of the main engine, whereby the main engine controls the
operation of both engines, the ports controlled by the supplemental valves being so
arranged that the supplemental valve of each engine uncovers its ports to steam and
exhaust when the other engine is about at the centre of its stroke, substantially as set
forth.
a
3. The combination with a main engine having a steam actuated main valve and a
supplemental valve for controlling said main valve, and an auxiliary engine having
steam actuated main valve and a supplemental valve for controlling said main valve,
of connections between the supplemental valves of both engines and the piston rod of
the main engine, whereby both of said supplemental valves are actuated by the main
engine, the valves and ports of both engines being of similar construction and so
organized that the main valve of each engine will be shifted before the piston of the
other engine completes its stroke, substantially as set forth.
4. The combination with a main engine having a steam actuated main valve and a
supplemental valve for controlling said main valve, and an auxiliary engine having a
steam actuated main valve and a supplemental valve for controlling said main valve,
of positive connections between the supplemental valve of the auxiliary engine and
the piston rod of the main engine, the ports controlled by said supplemental valve
being arranged to be opened to steam and exhaust when the piston of the main
engine is near the centre of its stroke, and mechanism also controlled by the main
engine for operating its own supplemental valve, the ports controlled by said valve
being arranged to be opened to steam and exhaust when the piston of the main
engine is at or near the end of its stroke, substantially as set forth.
5. The main engine, having a steam actuated main valve, a supplemental valve for
controlling said main valve, and tappets for shifting its supplemental valve at each
end of its stroke, in combination with an auxiliary engine, having a steam actuated
main valve, a supplemental valve for controlling the said main valve, and mechanism

page_text: controlled by the main engine for moving said supplemental valve, the ports that it
controls being arranged to be opened to steam and exhaust when the piston of the
main engine is near the centre of its stroke, substantially as set forth.
6. The combination of a main supplemental-valved direct acting engine, with an
auxiliary engine, a valve movement controlled by the main engine, for actuating the
valves of both engines and opening the ports of the auxiliary engine to steam and
exhaust when the main engine is at or near the centre of its stroke, and independent
steam pipes, having valves, whereby the steam may be cut off from the auxiliary
engine, and the main engine run alone, or the steam to both engines may be regulated,
substantially as set forth.
7. The combination with the two engines, having valves, of a rock-shaft, a positive
connection between said rock-shaft and the valve of one engine, tappets carried by said
shaft, means for communicating the motion derived from said tappets to the valve of
the other engine, and connections between said rock-shaft and the piston rod of one of
the engines, substantially as set forth.
8. The combination with two engines having valves, of the rock-shaft J, connection
between said rock-shaft and the piston of one of the engines, the short arm U, fixed to
said shaft, connections between said arm and the valve of one engine, the lever K,
connections between said lever and the valve of the other engine, and tappets carried
by the rock-shaft for moving said lever K, substantially as set forth.
9. The combination with the valve of an engine, the rock-shaft, and means for
moving the latter, of the short arm U, the slide T, and the valve rod Li', substantially
as set forth.
10. The combination with the piston rod, and a lever connected thereto, of the
rock-shaft J, having a plate N formed integral therewith, said plate having a bearing,
in which said lever fits, so as to be capable of sliding endwise, but incapable of lateral
movement relatively thereto, tappets n and n* on said plate, the lever K fulcrummed
loosely on said shaft and having the lug M projecting between said tappets and
connections between said lever and the engine valve, substantially as set forth.
Dated this 16th
h day of September 1800.
WILLIAM D. HOOKER.
By Harris & Mills,
23, Southampton Buildings, London, Agents.