IMPROVEMENTS IN STEAM ENGINES
Year: 1885

page_text: I, DEXTER DAVIS HARDY of the town of Lake View in the County of Cook,
State of Illinois, United States of America, Inventor, do hereby declare the nature
of my invention for "IMPROVEMENTS IN STEAM ENGINES" and in what manner
the same is to be performed, to be particularly described and ascertained in and
by the following statement:-
This invention relates primarily to a particular arrangement of two; four or
other multiple of two, single acting steam piston cylinders about a common crank
shaft with a crank on which each of the steam pistons is connected by a suitable
rod. Each pair of cylinders employed are placed on opposite sides of said crank
shaft and have motion in the same direction, preferably by being connected with
the same crank. In addition to this distribution of the cylinders about the crank
shaft, the axes of these cylinders are severally placed out of line with the radii
drawn from the axis of the crank shaft and parallel with and at the farther sides
of said radii, having reference to the direction in which the crank revolves. Thus,
for example, when two horizontal steam cylinders are present and the crank moves
upward and forward from right to left (as shown in the accompanying drawings) the
cylinder at the right is placed above, and that at the left below, a horizontal plane
containing the axis of the intermediate crank shaft. This opposite "offset" of the
cylinders is, for each, desirably about half the radius of the crank. By this.
arrangement, not only is the crank thrown by each piston successively more than
a half of one revolution and beyond the dead centre line with respect to the.
opposite connecting rod, but the angle of effective thrust of each connecting rod
with its piston is lessened so that a correspondingly short connecting rod may be
used and the entire Engine thereby be made compact.
Another feature of the invention relates to the location of the steam piston.
cylinders in a single plane at right angles with the crank shaft and the attachment
of the several connecting rods to the same crank, thereby obviating lateral or
torsional shake of the Engine when run at high speed while the pistons have the
same direction of motion. This construction also permits the Engine to be given a
running balance for all speeds by suitable counter weights applied to rotating parts
Prine S1

page_text: on the crank shaft, the irregularity of balance being in this case expended vertically
and tlierefore absorbed in the foundation and inertia of the machine.
Incident to this arrangement the invention embraces a peculiar construction
whereby opposite connecting rods work upon the same surface of the crank wrist.
This last construction consists in providing each connecting rod with only an end
bearing upon the crank wrist and in yoking the rods together by one or more rings
which bear upon. concentric circular surfaces on the rods and confine the ends of
the rods to the wrist.
Slide valves, and preferably of the "piston" order, one for each cylinder, are
employed and actuated by an excentric on the crank shaft to control the induction
of steam to the steam cylinders, and the exhaust is effected by ports in the steam
cylinders which are uncovered by the movements of the pistons themselves. Com-
pression on the back stroke of each of the pistons is relieved by a supplemental
port in the wall of the adjacent valve, which gives communication from the supply
port to the terminal exhaust passage of each steam cylinder. A further feature of
the invention relates to the connection of opposite piston valves with each other,
their arrangement in axial line with each other and with the axis of the crank
shaft and providing for a constant supply of steam behind each valve whereby said
valves are mutually balanced.
The shell or body of the Engine is a casting which forms a bed; a central
chamber for the crank shaft an oil well beneath the crank shaft; supports for the
crank shaft bearings and also suitable cored passages for the supply and exhaust
of steam. Removable covers complete the central housing. Desirably the steam
and valve cylinders are cast integral with the shell, and the valve gear is preferably
embraced within the housing.
The particular form in which the invention is illustrated in the accompanying
drawings is that in which only two opposite steam cylinders are employed and in
which these are horizontal. Referring to said drawings for a fuller description of
the invention ;-
Figure 1 is a longitudinal, vertical section in the generally vertical line x-x
of Figures 4 and 5.
Figure 2 is a longitudinal vertical section in the line y-y of Figures 4 and 6,
diverted as shown by the line ww of Figure 3.
Figure 3 is a view looking downward upon the Engine, the chamber covers
being removed and the top of the frame being cut off in the horizontal plane of line
x-x, Figure 1.
Figure 4 is a central vertical, transverse section in the plane of line x-x,
Figure 3.
Figure 5 is a vertical, transverse section in the plane of line y-y, Figure 3,
looking in the direction of the arrow.
Figure 6 is a vertical, transverse section in the plane of line 2-z, Figure 3,
looking in the direction of the arrow.
Figure 7 is a side view of the proximate ends of the connecting rods and their
yoke (broken) by which they are mutually confined to the crank wrist.
Figure 8 is a top view of the parts shown in Figure 7, the present portion of the
yoke rings being cut in the line v of Figure 7.
A, A, is the Engine frame, which is desirably a single casting. As shown, it is
constructed to form the base or bed, a central crank chamber of which the removable
parts A are covers, steam cylinders A¹ and A³, piston valve cylinders E E, duct D
and its extensions affording exhaust steam passages, and a top or bridge piece
affording inlet steam passages a¹, and attachment for the upper part of the
covers A. The lower portion A³ of the crank chamber constitutes a well for oil by
which the inner moving parts are lubricated, and the vertical sides of said chamber
which terminate in the horizontal flanges a³, afford support and bearings for the
transverse crank shaft C. The flanges a continue upward and across the bridge
piece of the frame as seats for the side covers A*.

page_text: The equal steam cylinders A¹ A2 are closed at their outer ends by suitable heads
and open into the central crank chamber. Within the steam cylinders are fitted
single acting trunk pistons in each of which is pivoted in the usual way a rod b
connecting the piston with the crank c on the intermediate crank shaft C. The
crank c in this instance has movement in the direction indicated by the arrow
Figure 1. The axis of cylinder A³, therefore, is located about half the radius of
this crank above a horizontal plane passing through the axis of the crank shaft
and the axis of the cylinder A' is located correspondingly below said plane. By.
this means each connecting rod b makes its thrust at a relatively slight angle with
the axis of its piston with the result that said rods may be very short and the
Engine may be made correspondingly compact.
The steam cylinders A¹ A' are shown situated in the same vertical plane and
their connecting rods engaged with a single crank on shaft C. This obviates
torsional or lateral shake or motion of the Engine when run at high speed and
leaves only the momentum of the reciprocating parts to be balanced when the
pistons are horizontal. This will be accomplished as perfectly as may be desired
by the application of counter weights to revolving parts (as fly-wheels or crank
discs) on the crank shaft, in a familiar way. When the opposite cylinders are
vertical (as they may be) the momentum will be absorbed or lost in the foundations
and in the inertia of the machine.
In order that both connecting rods may bear on the same surface of the crank
wrist c¹ and each may therefore bear throughout the entire length of said wrist,
neither rod entirely embraces the wrist but abuts against it, both being confined to
the wrist by one or more rings or yokes 62 which embrace the parti-cylindric outer
surfaces of the lateral extensions b₁ on the proximate ends of said rods, all as plainly
shown in Figures 7 and 8.
EE are cylinders for piston valves E¹ E¹, which are severally arranged at one
side of the cylinders A¹ A³ and with their axes in line with each other and in the
plane of the shaft C. The valves E¹ are directly connected with each other by the
axial rods e and central yoke e³ embracing the crank shaft C. The valves are
actuated by an excentric set on the shaft C at the proper position to give lead
steam to the Engine. The strap e¹ on the excentric is attached to a rod e² which is
pivoted at its opposite end to one of the rods e. By this linear arrangement of the
valves E' and by providing for a constant live steam pressure behind each valve (as
by passages a) said valves are mutually balanced.
These valve connections are shown as contained within the housing but, if
desired, they may be made external thereto by shifting the position of the cylinders
on the frame..
The steam inlet passage a¹, as indicated, is cored in the upper central part of
the frame, receives the supply pipe a at the middle, extends down the ends of the
chamber walls and outward over the junction of the steam and valve cylinders
whence it passes laterally around the latter forming the desirably broader passage
shown at a in Figures 2 and 3. This annular passage a² opens into the valve
cylinder by a series of short passages e separated by intermediate bars, at a³, as
shown in Figure 6, and located at a distance from the head of the valve cylinder
equal to the horizontal width of the port leading from the valve cylinder to the
steam cylinder, plus the clearance, so as to give a desired lap to the valve.
A supplemental passage a opens from the passage a² into the extreme end of the
valve cylinder for the purpose of maintaining a live steam pressure behind both
valves to balance them. Each valve cylinder communicates with the adjacent
steam cylinder by a port a³, Figures 2 and 6, also located preferably a short distance
inward from the cylinder head, and is of course adjusted relative to the back stroke
of the piston so as not to be entirely closed thereby.
Steam is exhausted from each of the piston cylinders through an annular series
of ports d² located in position to be uncovered when the piston has reached the
limit of its forward stroke, and delivering into the passage d, whence it passes

page_text: through d¹ to a suitable common outlet. In this instance the pipes d¹¹are cast
with the frame and are connected by a cored duct D, and at D¹ is shown a single
pipe which may lead to any desired point of delivery.
To relieve the back pressure from compression of steam behind the pistons in the
steam cylinders on the back stroke of said pistons a longitudinal groove or passage et
(see Figure 5) is cast in the external surface of the wall of each valve piston, the
extremities of said passage being in such position (as indicated by dotted lines
Figure 2) that when the valve has cut off the steam supply to the steam cylinder
said passage e will give communication between the steam supply port a³ and the
exhaust port d.
In order to give a straight surface on each of the flanges a³ on which to bolt the
lower edges of the covers A* the said flanges are recessed to receive the bearing
caps a flush therewith.
It is to be understood that I am not restricted to the form or position of the
steam ducts or to their being cored in the frame casting, and it is also to be under-
stood that details of construction throughout the machine may be varied without
departure from my invention.
Having now particularly described and ascertained the nature of my inven-
tion, and in what manner the same is to be performed, I declare that what
I claim is
1. In a steam engine, the combination, with a crank shaft, of two steam
cylinders placed on opposite sides of the shaft and having their axes on opposite
sides of, and parallel with, a plane containing the axis of the crank shaft; trunk
pistons fitted to said cylinders; a rod connecting each of said pistons with a crank
on the crank shaft; and, slide valves and suitable connections thereof with the
crank shaft for controling the supply of steam to the steam cylinders, said cylinders
having supply ports communicating with the valve chambers and having terminal
exhaust ports which are opened and closed by the steam pistons, substantially as
described.
2. In a steam engine, the combination, with a crank shaft, of two steam cylinders
placed on opposite sides of the crank shaft and with their axes on opposite sides of
a plane containing the axis of said shaft and also placed in the same plane at right
angles to said shaft; trunk pistons fitted to said cylinders; rods connecting these
pistons with a single crank on the shaft, and slide valves and suitable connections
of said valves with the crank shaft for controlling the supply of steam to the steam
cylinders, said cylinders being provided with supply ports and with terminal
exhaust ports which are opened and closed by the pistons themselves, substantially
as described.
3. In a steam engine, the combination, with a crank shaft, of two steam
cylinders placed on opposite sides of the crank shaft and offset, as described, on
opposite sides of a plane containing the axis of said crank shaft; pistons fitted to
said cylinders and connected by suitable rods to the crank of said shaft; connected
piston valves arranged in axial line with each other and also connected by suitable
operating devices with the crank shaft, for the control of steam supply to the steam
cylinders, and means for maintaining live steam pressure behind each piston valve,
the steam cylinders being provided with suitable supply and exhaust ports,
substantially as described.
4. The combination of a crank shaft having a single crank thereon; oppositely
placed and oppositely offset steam cylinders located in the same plane at right
angles to the crank shaft; trunk pistons connected by rods with the single crank
of the crank shaft; connected piston valves arranged in axial line with each other
and having working connections with the crank shaft; inlet steam passages arranged
to maintain live steam pressure at the ends of the piston valves; supply steam
ports leading from the piston chambers to the steam cylinders, and terminal exhaust

page_text: ports leading from the steam cylinders which are opened and closed by the pistons,
substantially as described.
5. The combination, with the oppositely arranged single acting steam pistons
and an intermediate shaft having a single crank, of connecting rods abutting on the
same crank wrist and connected by a yoke or yokes which confine the rods to the
wrist, substantially as described.
6. The combination, with the oppositely arranged steam cylinders and their
pistons connected with an intermediate crank shaft, said cylinders being provided
with suitable steam supply ports and with terminal exhaust ports which are opened
and closed by the pistons, of piston valves provided with passages in their side
walls giving communication between the supply and exhaust ports of the steam
cylinders for the relief of steam compression in the steam cylinders, substantially as
described.