Improvements in Rotary Engines.
Year: 1896

page_text: Date of Application, 16th June, 1896-Accepted, 15th Aug., 1896
Improvements in Rotary Engines.
I WILLIAM EDGAR PRALL Jr., of High Bridge in the City and County of
New York in the State of New York, United States of America, Engineer, 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:-
My invention relates to improvements in rotary engines in which rotary pistons
are forced alternately in the same direction under the pressure of the actuating
fluid, which may be either steam or gas, said rotary pistons being alternately
clutched to a rotary part, which serves as a driver for transmitting power to be
applied to such purposes as may be desired, and to a stationary part to form an
abutment for the actuating fluid, while forcing the movable piston and the part
locked thereto.
In the accompanying drawings,
Fig. 1 is a view of the engine in longitudinal vertical section.
Fig. 2 is a view in transverse section, on the plane of line 2-2 of Fig. 1,
looking towards the right, as the drawing is held in reading.
Fig. 3 is a transverse section on the plane of the line 3-3 of Fig. 1, looking
in the same direction.
Fig. 4 is a transverse section on the plane of line 4-4 of Fig. 1, looking towards
the left, as the drawing is held in reading.
Fig. 5 is a similar view, showing the position of the pistons when they have
advanced from the position where one is about taking steam to the position of
steam-port full open.
Fig. 6 is a similar view on the plane of line 6-6 of Fig. 1, showing the position
of the pistons when one of them is advanced to the position of full open exhaust.
Fig. 7 is a similar view of the plane of line 7, 7 of Fig. 1, showing the companion
piston in the position of steam inlet port full open.
Fig. 8 is a similar view on the plane of line 8-8 of Fig. 1, showing the
companion piston advanced to the position of full open exhaust; and
Fig. 9 is a transverse section of a modified form."
In using the word "steam" in connection with the description of the structure
and operation of the parts, I wish to be understood as referring to the actuating
fluid, whether it be steam or gas.
Furthermore, while I have (for purpose of illustrating my invention) shown a
rotary cylinder as the driving part, it will be readily understood that the shaft
may be utilised as the driving part, and the cylinder held stationary, if so desired.
In suitable supports A, A, there is fixed a hollow shaft B, which is utilized for
supporting the rotary pistons and the rotary cylinder mounted on the hubs of the
pistons, and also for the transmission of the actuating fluid and its escape from the
interior of the cylinder. The end of the shaft B for the inlet of the actuating
fluid is denoted by b, and the outlet by b¹.
The cylinder C is mounted at its ends upon the hubs d, d' of the pistons D, D',
which hubs are in turn mounted upon the shaft B, and extend beyond the ends of
the cylinder, where they are provided with clutching wheels or discs E E', fixed
to rotate with the pistons, the wheel or disc E with the piston D, and the wheel
or disc E with the piston D'.
The pistons each consist of a pair of wings or blades extending in opposite

page_text: directions from the hub, each constructed to extend from the hub to the inner
curved surfaces of the cylinder, forming a loose joint with the interior faces of the
ends of the cylinder, and with the interior curved surface of the cylinder. The
hubs d d of the pistons each extend from about the middle of the cylinder,
through the end of the cylinder, and outwardly beyond the end of the cylinder,
the wings of one piston being arranged to overlap the hub of the adjacent piston.
The peripheries of the discs E, E¹, are each provided with a pair of annular
grooves, in the present instance made V-shaped in cross section, the grooves on the
periphery of the disc E being denoted by e, e', and those on the disc E' by e, e³.
Along these grooves e, e', e, e³, clutching shoes F are located, for the purpose of
temporarily clutching the pistons alternately to the cylinder and to a stationary
support. In the present instance, I have prepared three of these clutching shoes
in each of the grooves in the peripheries of the clutching discs, but the number
may be greater or less than three, as may be found most desirable. The clutching
shoes are quite similar to one another, and are each made with a V-shaped inner
face, to correspond to the groove in the clutching disc, and of a curved form
corresponding to the are of the periphery of the clutching dise, and intermediate
of their ends, they are provided with a depression f for the reception of a loose
connection, which I call a toggle clip. The so-called toggle clip consists of a body
portion G, provided with laterally extending noses g g', one at its upper, and one
at its lower end, the nose g at its upper end being adapted to rest within the
depression f in the back of the clutching shoe, and the nose g¹ being adapted to
rest within a depression in the inner side of the cross head of a loop projecting
either from the cylinder head or from the fixed support, those projecting from the
fixed support being denoted by H, and those projecting from the heads of the
cylinder being denoted by H. As a matter of convenience and economy in
structure, I make the rims of the clutching discs E, E broader than the web
portion, so that the heads of the loops H H' may be located in the same transverse
plane as the clutching shoes in the grooves on the peripheries of the clutching
discs, as clearly shown in Fig. 1.
The toggle clips have sufficient play in their engagement with the clutching
shoes and the loops H H', to permit the clutching shoes to ride loosely along the
grooves in the peripheries of the clutching discs, when the toggle clips occupy
positions along radial lines with respect to the axis of rotation, but when the said
toggle clips are thrown into an oblique position, the tendency is to promptly draw
the clutching shoe inwardly into snug frictional contact with the periphery of the
clutching disc, and thereby lock the clutching disc either to the cylinder or to the
stationary support, depending upon the particular set of toggle clips which, for
the moment, are brought into oblique positions.
Each toggle clip has its upper portion normally pressed slightly to one side by
means of a spring 1, the springs for pressing the clips, for locking the clutching
disc to the fixed support, being fixed to the loops H, and those for tilting the clips,
for locking the clutching disc to the cylinder, being fixed to the loops H', and
constructed to press upon the clips in the opposite direction from that in which the
springs fixed to the loops H press. The object of this arrangement and action of
the springs, is to hold the clutching shoes in such relation to the periphery of the
clutching disc, that when the clutching disc is operated in the direction corre-
sponding to that in which the springs press, the tendency will be to throw the shoe
into snug contact with the disc, and cause it to drag after it, in its rotary move-
ment, the part to which the toggle clips are secured. If such part be the rotary
part (in the present instance, the cylinder), it will be carried along with the
clutching disc, but if it be the stationary part, the clutching disc will be held
against a rotary movement by such clutching action. When, however, the
clutching disc is rotated in a direction opposite that in which the springs press,
the tendency will be to prevent the clutching shoe from coming into snug contact
with the periphery of the clutching disc, and it will be permitted to rotate freely
in that direction.

page_text: As there are sets of toggle clips at each ent of the cylinder, one set for locking
the cylinder to one of the rotary pistons, and the other set for locking the cylinder
to the other rotary piston, and in connection with these sets of toggle clips for
locking the pistons to the cylinder, there are also located, at the opposite ends of
the cylinder, sets of clips, one set for locking one of the pistons to the fixed
support, and the other set for locking the other piston to the fixed support, it
follows that one of the pistons may be, by means of its clutching disc, locked to
the cylinder, while the other piston, by means of its clutching disc, is locked to the
fixed support, and the remaining sets of clutching shoes may be, for the time
being, released from the peripheries of the clutching discs, and such an arrangement
is practically carried into effect by the location of the springs I, as shown in the
drawings, which tend to press the sets of toggle clips for locking the clutching
discs to the cylinder in the opposite direction from that in which the toggle clips
are pressed for locking the clutching discs to the fixed support.
The actuating fluid for advancing the pistons within the cylinder is admitted
from the interior of the shaft B to the space between the pistons in the cylinder,
and discharged from said space by ports formed in the wall of the shaft B, and in
the hubs of the pistons, as follows:-The interior of the shaft B is provided with
a diaphragm 2, which separates the high-pressure actuating fluid from the low-
pressure or exhaust, the diaphragm 6 being provided with a centrally elongated
loop, as clearly shown in Fig. I, so as to admit of the location of the inlet ports
within the transverse planes through the hubs of the two pistons. The inlet ports
through the hub of the piston D are denoted by K, K', (see Fig. 4), and the
corresponding inlet ports in the shaft B by k k'. The inlet ports through the hub
of the piston D' are denoted by L, L' (see Fig. 7), and the corresponding inlet
ports in the shaft B by . The exhaust ports in the hub of the piston D are
denoted by M, M' (see Fig. 6), and the corresponding ports in the shaft B by m m'.
The exhaust ports in the hub of the piston D' are denoted by N, N', and the
corresponding outlet ports in the shaft B by n n'.
The operation is as follows:-
Referring to the sections shown in Figs. 4, 5, 6, 7, and 8, as the piston D moves
in the direction of the arrow, to admit the actuating fluid through the ports k, k¹,
K, K', into the spaces between the two pistons, it will have a teudency to rotate
them in opposite directions. The piston D' is prevented from rotating in the
direction in which it is pressed by the actuating fluid, because of the tendency of
the toggle clips in engagement with its clutching disc, to hold it tightly to the
fixed support, but the piston D is free to advance in the direction in which it is
pressed, because of the tendency of the toggle clips on its clutching disc, to release
it from the fixed support. The movement of the disc E in the direction of the
arrow, tends, however, to lock the clutching disc to the cylinder, and it will
therefore drag around with it, in its rotary movement, the cylinder C. As it
approaches the position of the piston D', it will, after passing the position of full
open inlet (shown in Fig. 5), and the full open exhaust (shown in Fig. 6), cushion
against the piston D', tending to start it upon a rotary movement in the same
direction in which the piston D was rotated. This will free the piston D' from
the fixed support to which it was clutched, and will, by its rotary movement, open
the inlet ports L, L, 1, 1, (see Fig. 7), for the admission of the actuating fluid,
which will continue to press it forward in the direction in which it started, and
will, at the same time, tend to press the piston D in the opposite direction from
that in which it was rotating.
The piston D' will, in turn, however, be clutched to the fixed support, when any
tendency is exerted upon it to rotate it in the opposite direction, and the effect will
be to force the piston D' forward, and it will, in turn, be clutched to the cylinder,
to drag it around in the same direction in which it was started by the piston D.
As the piston D' approaches the piston D, after passing the full open exhaust
shown in Fig. 8), it will in turn cushion against the piston D, and force it
orwardly, to open the inlet and repeat the operation.

page_text: It will be observed that each piston carries with it the cylinder throughout one
half or more of its revolution, so that there is no frictional wear between the piston
and the cylinder throughout at least one half of the revolution of the piston, and
when the engine is running under a light load, the momentum of the cylinder and
piston will tend to carry the pistons-both of them-along with the cylinder,
making such a quick opening and closing of the inlet ports, as to prevent useless
admission and exhaust of the actuating fluid, but as soon as the load upon the
engine requires additional force to carry it, the inlet of the actuating fluid will be
provided, without any care on the part of the operator.
It will be observed that the clutching is effected by drawing the clutching shoes
towards the axis of the part to be clutched by them, instead of pushing them away
from said axis. This admits of pulling the clutching shoe to the periphery of the
part to be operated, instead of to an inner and less advantageous portion.
In the form shown in Fig. 9, the clutching shoes F₁, corresponding to the
clutching shoes F in the form already described, are pressed outwardly against
the inner curved surface of an annular rim Q, by means of toggle dogs R, which
seat at one end in a depression s, formed in the back of the shoe, and at the
opposite end in a suitable seat formed therefor in the extended hubs d, d', of the
pistons. The dogs R are made adjustable in length, preferably by means of a
right and left screw-threaded sleeve r, in which the screw-threaded shanks of the
dogs are engaged. The shoes F¹ are normally pressed in the direction to promptly
clutch the part desired by means of interposed springs S. In all other essential
respects, the operation of the engine is the same when the toggle dogs are employed,
as when the toggle clips herein above particularly described are used.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, 1 declare that what I
claim is :-
1. A rotary engine comprising two parts, a shaft and a cylinder, a plurality of
pistons mounted within the cylinder, and serving as valves for the admission and
discharge of the actuating fluid, the said pistons being free to rotate independently
of one of the said parts, and the other of said parts being at the same time free to
rotate independently of the pistons, and means for clutching the pistons to one of
said parts and to a stationary part, substantially as set forth.
2. A rotary engine comprising a cylinder, pistons mounted to rotate within the
cylinder, and serving as valves to admit and discharge the actuating fluid, means
for clutching the pistons to, and releasing them from, the cylinder; parts located
in proximity to the cylinder; means for clutching the pistons to and releasing them
from said parts, the cylinder and the clutch receiving parts adjacent to the cylinder
being the one supported to rotate and the other stationary; and means for
conducting the actuating fluid to and from the interior of the cylinder, substantially
as set forth.
3. The combination with a cylinder and a shaft on which the cylinder is mounted,
the shaft and the cylinder being the one fixed and the other mounted to rotate, of
pistons mounted to rotate freely within the cylinder; means for preventing the
rotary movement of the pistons in one direction; clutching shoes carried by the
aforesaid rotary part; and means for drawing the clutching shoes towards the axis
of rotation of the pistons, for locking the rotary part to the pistous, substantially
as set forth.
4. The combination with the cylinder, the pistons mounted within the cylinder,
to rotate freely in one direction, and means for preventing the pistons from rotating
in the opposite direction, of clutching wheels or discs fixed to rotate with the
pistons; clutching shoes carried by the cylinder; and means for drawing the
clutching shoes towards the axis of rotation of the pistons, to lock the cylinder to
the pistons, substantially as set forth.
5. The combination with the shaft, the pistons mounted to rotate freely on the
shaft, and the cylinder mounted to rotate freely on the hubs of the pistons, of

page_text: clutching discs carried by the hubs of the pistons; a set of clutching shoes secured
to a fixed support; a set of clutching shoes secured to the cylinder; and means for
drawing the clutching shoes towards the periphery of the clutching discs, as the
pistons are forced in the one or the other direction, substantially as set forth.
6. The combination with a shaft, pistons mounted to rotate freely on the shaft,
a cylinder mounted to rotate freely on the hubs of the pistons, and clutching discs
carried by the hubs of the pistons, of different sets of clutching shoes in position to
engage the periphery of each clutching disc; toggle clips engaged with the
clutching shoes, and with a fixed support and the cylinder respectively, for locking
the shoes to the clutching discs; and means for tilting the toggle clips, to determine
the direction in which they shall clutch the disc, substantially as set forth.
Dated this 16th day of June 1896.
NEWTON & SON,
Agents for the Applicant.