IMPROVEMENTS IN ROTARY STEAM ENGINES
Year: 1886

page_text: I, DAVID LOND CROSS, of Austin, in the County of Travis and State of Texas,
in the United States of America, Engineer, do hereby declare the nature of my
invention for IMPROVEMENTS IN ROTARY STEAM ENGINES, and in what manner
the same is to be performed, to be particularly described and ascertained in and
by the following statement:-
My improvement in Steam Engines is particularly applicable where frequent
reversing of movement is required, but is equally applicable in driving any class of
machinery. The engine is provided with two fixed shallow cylinders one on either
side of a central point in the main or driving shaft. Each cylinder has within it a
piston provided with a head which revolves upon and with the driving shaft, both
being permanently keyed to it. At a central point upon the driving shaft, between
the two cylinders, is fixed a cam wheel which has two annular grooves, not parallel
to each other, each of which engages a rod sliding in a race which is connected with
and operates a pair of slide valves to open and close induction and exhaust ports
which lead to the cylinder chambers and simultaneously with these movements
opens and closes the cylinder chambers by moving the abutments in a line parallel
with the axis of the main shaft. The abutments form at times diaphragms to
direct steam and confine it between the piston heads and abutinents. My engine,
as shown in the drawings, has four combined induction and eduction cocks, four
slide valves, four induction ports, and four exhaust ports; two of the induction
ports connect with the cylinder on one side of the cam wheel, and the other two
connect with the cylinder on the opposite side of said wheel. Each cylinder has
passing from it two exhaust ports which discharge through their respective cocks.
Steam enters the cylinders starting first on one side and then on the other, from
steam pipes which enter the combined cocks at points longitudinally opposite, the
two others transversely opposite to these being at the time closed against the
entrance of steam, but which serve, meanwhile, as exhaust cocks. The two com-
bined induction and eduction cocks on either side of the cam wheel are connected
with cranks which surmount their valve stems by an arm connected to a shaft
journaled to the engine frame by a lever and a hinged arm, so that when said
shaft is moved by the engineer frontward or backward, longitudinally opposite
cocks and ports are opened and the two others closed to reverse the motion of the
driving shaft and machinery connected thereto. The grooves in the cam wheel
are formed exactly parallel to the central plane of said wheel one half its circum-
ference, while their other halves run inward toward said plane nearly touching
said plane in the periphery of said wheel at exactly opposite points. By this
arrangement of cam grooves, opposite slide valves and abutments are reciprocated
alternately, one set with reference to the other at each revolution of the shaft, and
.

page_text: impulse is given to one piston or the other the entire time that the portions of the
grooves parallel to the plane of the cam wheel are traversing the friction rollers
of the sliding bar to move the abutments and slide valves.
The piston heads of the two cylinders are fixed in radial lines from the axis of
the driving shaft exactly 180°, the one with reference to the other, and this
arrangement facilitates a uniform movement to said driving shaft while steam is
supplied the cylinders, precluding the possibility of dead points to check the
movement of the machinery.
In the drawings, Fig. 1, is a top plan view of the engine. Fig. 2, a horizontal
section through the steam chests exhibiting the exact relation between the slide
valves and other parts on either side of the cam wheel. Fig. 3, a longitudinal
section in a vertical plane showing the cylinders, the cam wheel, sliding bars con-
necting slide valves, abutments &c. Fig. 4, a transverse section through valves
and steam_chest on one side of the cam wheel. Fig. 5, a front elevation of the
engine. Figs. 6 and 7, are elevations of the interior of the steam cylinders
exhibiting the relative positions of the abutments of the pistous, when steam is
entering one and exhausting in the other. Fig. 8, shows the arrangement of one
of the combined cocks.
A, is the main, or driving, shaft connected with my engine, which passes through
cylinders B B¹, and to which is fixed pistons OC, and cam wheel D, provided
with grooves g, h. The cylinders B B₁, are formed in two parts and secured
together by bolts &c in the usual manner. They have the ordinary packing rings
to make them steam-tight. When the parts of the cylinder are placed together
spaces M M¹, are enclosed, forming chanuels for the passage of steam received by
the eduction ports and exhausted from the exhaust ports. Between the pistons
and the outer heads of the cylinders are formed annular spaces i, i, which serve to
receive any steam escaping through the joints by the expansion of which packing
purposes are served. The cylinders B B¹, and their immediate surroundings are
precisely similar in construction so that a description of the parts on one side of
the cam wheel will answer as a description of the parts on the other side of said
wheel. Within the steam cylinder B, on the left, which is immovably secured to
the frame of the engine, is the rotary piston keyed to the shaft A, and provided
with a piston head a. Immediately under the driving shaft A, is an abutment N,
which plays through the inner head across the chamber and through the other
head of the cylinder. This abutment is connected to the yoke L by a rod f, and
through upright O, to the rod K, which moves in a groove and connects with the
cam groove g. Rod K, is provided with an upright pin to which is loosely secured
an anti-friction roller j, to modify friction to the bearing surface of said groove g.
Slide valves J J¹, are secured to the yoke L, and these valves and the abutment N,
move simultaneously and rest simultaneously, influenced by the groove g, during
the motion of the cam wheel, through the sliding rod K. F, is a double steam chest
located next to the steam cylinder B, and between it and the cam wheel D. This
chest has chambers, provided with openings m m¹, for entrance of steam, and
ports bb, which open into the steam cylinder B. J J, are the slide valves provided
with stems e e¹, moved from the cam wheel to open and close the induction 4
ports 6 6. Cocks E E³, are located at points, as shown, convenient to the steam
cylinder B, and slide valves J J. The construction of one of these cocks is shown
in fig. 8. This cock has a valve provided with two openings, one above the other,
and parallel, the upper communicating with the exhaust port from the steam
cylinder and the lower connecting with the steam pipe which brings the supply of
steam from the boiler. .
"
As seen in figs. 1 and 2, cock. E, is so fixed that live steam may enter the
chest when the slide valve on that side is open and the abutment of the
cylinder B, is in place in said cylinder. Steam passes through the opening m,
thence through chamber l, and port b, into said cylinder behind the piston head; &
at this time the cock E, is so closed so that no steam may enter the cylinder on its
side, but its exhaust orifice b*, being open, dead- steam-finds its way from in front

page_text: of the piston head C, out through the exhaust port on that side. The cooks E E',
are, by cranks p p¹, link bar g, arm t, and shaft S, shifted at the option of the
operator to change their relations with reference to the piston head and make ono
side or the other the induction and its opposite the exhaust aide. It is obvious,
from the construction of the cocks and their connecting arrangements, that one
must always be open for live steam while the opposite serves as an exhaust cock.
The shaft S, serves to connect the two sets of valves on opposite sides of the cam
wheel, so that by one movement of the arm r, in the hands of the operator, all four
of these combined cocks are operated at one movement; two opposite ones, as E E,
are opened for the entrance of live steam, and closed for exhaust, while the other
two are closed to.live steam and opened for exhaust.
This simultaneous movement of cocks throws the power of the engine in a
manner to drive the main shaft first in one direction and then in the other,
carrying the machinery influenced either way at the will of the operator at any
moment without injury to the operating parts of the engine.
It may be observed that the abutments of the engine move across the steam
cylinders and into openings in the outer cylinder heads before the alide valves open
their respective ports, therefore no live steam is lost; and when these valves are
open, steam acts positively upon the piston heads with both primary and expansive
force, thus giving maximum results and rapid movement. The steam valves close
also before the abutments are withdrawn through the cylinder chambers, so that no
exhaust steam is gotten rid of before a new supply of live steam is taken in. It
may also be observed that, in this arrangement of the pistons on either side of the
cam wheel, the head of one bears such a relation to the head of the other that full
steam is at all times acting upon one or the other so that the movement to the
driving shaft is positively uniform and constant while the engine is in operation,
giving advantages over any system now in use that I am aware of.
In my drawings I have shown two double steam chests with double slide valves
and steam cocks, and this arrangement is necessary when the reversing mechanism
is required, but where it is not necessary to use the reversing machinery, single
steam chests, single slide valves, and one cock only, is necessary on each side of
the cam wheel. In the latter application steam is received from but one side
of the driving shaft, and the exhaust takes place from exhaust ports arranged on
the opposite side.
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. A cam wheel applicable to a steam engine and adapted to move in a plane at
right angles to the axis of the driving shaft, provided with two cam grooves each
of which is parallel with a right cantral plane of said wheal one half of said wheel's.
circumference, the other half of said grooves having direction inward toward.said
central plane with the greatest inward variance of the one at an angle of 180°,
to the greatest inward variance of the other, substantially as and for the purpose
set forth.
2. In a steam engine, the cam wheel having two annular grooves formed in a
manner substantially as described, fixed to the main or driving shaft by which
motion is imparted from said shaft in opposite directions in a line parallel with the
axis of said shaft to operate certain mechanism connected with the-steam cylinders,
as and for the purpose set forth.
3. A cam wheel formed substantially as described, fixed upon the driving shaft
of a steam engine, one of the grooves of which gives motion to a steam abutment
and one or more slide valves on one side of said cam wheel simultaneously, and the
other of said grooves alternately with the first, giving corresponding motion to an
abutment and slide valves on the opposite side of said wheel, as set forth.
4. A steam engine having two steam cylinders, one fixed to a base upon one side
and parallel with a central plane, and one upon the opposite side of the said plane,

page_text: said cylinders being set with their common axis coincident with the axis of the
driving shaft, in combination with concentric pistons provided with suitable piston
heads, substantially as described, fixed upon and moving said driving shaft when
influenced by steam received into and discharged from said cylinders, substantially
as described.
5. The combination with a steam cylinder fixed about the axis of the driving
shaft of an engine, and a rotary piston fixed to and moving with said driving shaft,
provided with a suitable head, of an abutment having an alternate movement into
and out of said cylinder with an interval of rest, a rotary cam wheel provided with
annular grooves about its periphery and suitable rod connections for said cam
wheel and abutment, all arranged as and for the purpose set forth.
: 6. The combination with the cylinder, rotary piston, and steam abutment,
substantially as described, of the slide valve operated from the motion of the main
driving shaft through the influence of the cam wheel grooved in its periphery and
fixed to the driving shaft, and suitable connecting mechanism, as and for the
purpose, substantially as set forth.
•
7. The combination with the steam cylinder fixed at opposite points about the
axis of the driving shaft and provided with induction and exhaust ports, the rotary
pistons, movable abutments, steam chests, and slide valves, of the rotary cam wheel,
located between the steam cylinders upon the driving shaft, provided with cam
grooves on its periphery and connecting mechanism for the abutments, slide valves
and cam wheel, substantially as specified.
8. The reversing mechanism composed of cocks E Ẹ¹, Eº E³, shaft S, arm r,
levers t t¹, and link 'bars q q¹³, and cranks connected to said cocks whereby steam is
changed and directed from one side of the abutments of the steam cylinders to the
other to give forward or backward movement to the pistons and driving shafts,
substantially as set forth.
9. The combination with a steam chest and a slide valve moving horizontally
therein, and the combined induction and eduction cocks, of the fixed concentric
cylinder and rotary piston fixed to the driving shaft and moving in said cylinder,
and the steam abutment moved horizontally from a concentric cam wheel, grooved
as described and fixed to said driving shaft, as and for the purpose set forth.
10. A steam engine having duplicate cylinders and rotary pistons arranged
about the axis of the driving shaft, duplicate slide valves and abutments arranged
and moved in connection with a cam wheel having two cam grooves substantially
as described, whereby said pistons are rotated by force of steam which enters aud
continues to enter through an induction port into one cylinder to drive its piston
half a revolution and cuts off simultaneously with the entrance and continued
entrance of steam in the opposite cylinder during a half revolution, thus keeping
up an unabated steam pressure and movement, consequently, to the driving shaft,
substantially as set forth.
11. The combination with the steam cylinders provided with suitable ports,
located at opposite points above the axis of the driving shaft, the piston fixed to
the driving shaft and moving with it within the said cylinders, of the double
grooved cam wheel, the slide valves, the induction and exhaust ports connected
with the cylinders and slide valves the steam abutments and induction and
eduction cocks, all arranged as and for the purpose set forth.
ALLISON BROB,
Agents for the Applicant.