CERTAIN IMPROVE- MENTS IN ROTARY ENGINES AND PUMPS
Year: 1872

page_text: LETTERS PATENT to Benjamin Joseph Barnard Mills, of the Firm of
Harris and Mills, of 35, Southampton Buildings, in the County of
Middlesex, Patent Agent, for the Invention of "CERTAIN IMPROVE-
MENTS IN ROTARY ENGINES AND PUMPS." A communication from
-
abroad by Erastus S. Bennett, of the City of Brooklyn, in the
County of Kings, and State of New York, United States of America,
Doctor of Medicine.
Sealed the 20th September 1872, and dated the 30th July 1872.
COMPLETE SPECIFICATION filed by the said Benjamin Joseph Barnard
Mills at the Office of the Commissioners of Patents, with his
Petition and Declaration, on the 30th July 1872, pursuant to the
9th section of the Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, BENJAMIN
JOSEPH BARNARD MILLS, of the Firm of Harris and Mills, of 35,
Southampton Buildings, in the County of Middlesex, Patent Agent,
send greeting.
WHEREAS I am in possession of an Invention for "CERTAIN IMPROVE-
MENTS IN ROTARY ENGINES AND PUMPS," and have petitioned Her Majesty

page_text: to grant unto me, my executors, administrators, and assigns, Her Royal
Letters Patent for the same, and have made solemn Declaration that it
has been communicated to me from abroad by Erastus S. Bennett, of
the City of Brooklyn, in the County of Kings, and State of New York,
United States of America, Doctor of Medicine.
NOW KNOW YE, that I, the said Benjamin Joseph Barnard Mills, do
hereby declare that the following Complete Specification, under my hand
and seal, fully describes and ascertains the nature of the said Invention,
and in what manner the same is to be performed, in and by the following
statement thereof, that is to say:
This Invention relates alike to rotary engines and rotary pumps, the
construction of many of the parts being similar in all essential respects,
whether the apparatus be employed to transmit and apply power from
steam, compressed air, or other fluid, or to force any fluid, such as water
or air, by power applied to its central shaft.
The improvements comprise,-
•
First. An elliptical or ellipsoidal casing containing a central shaft-
and a cylindrical hub, in which are a number of radial pistons which
in their revolution are kept constantly in contact with the interior of
the casing by the action of stationary cams on which the sliding pistons
ride.
Second. A novel combination of valve and ports with the casing,
rotary hub, and pistons, said valve and ports affording a simple and
convenient means of stopping, starting, and reversing the engine.
I
Third. Supplementary ports or ducts, by means of which the fluid
may be made to act simultaneously on two pistons on opposite sides of
the rotary hub.
Fourth. Recesses provided on the interior of the cylinder or casing
permitting the fluid to pass freely around the sliding pistons just before
they come into action and after they go out of action, by which means
obstruction of the ports and passages is avoided, and the pressure is
balanced on their opposite sides when they are not in operation.
Fifth. A mode of applying rollers to the sliding pistons to reduce
friction.
Sixth. A mode of applying shoes and springs to the said sliding
pistons to cause them to slide with greater freedom.

page_text: Seventh. A soft metal packing or bushing applied to the guides or
grooves in which the pistons slide.
Eighth. A combination of sliding pistons, shoes, springs, and stationary
cams in a rotary engine, substantially as herein-after described.
Ninth. Appliances for lubricating the moving parts.
The casing or "cylinder" may be of any suitable elliptical form in its
transverse section, but it is preferred to form the parts which are
traversed by the pistons while they are effective in arcs concentric with
the central rotary hub, which is of cylindrical form, and carries the
sliding pistons. The intermediate portions of the casing are contracted
to about the radius of the rotary cylindrical hub coming in contact with
the latter, and forming abutments against which the steam reacts (in
the case of a steam engine).
The stationary cams which force the pistons outward at proper periods
have surfaces parallel with the periphery of the casing, and thus keep
the outer edges of the pistons constantly in contact with the interior of
the casing...
The steam and exhaust ports (or in the case of a pump, the inlet and
discharge ports) are located one on each side of the contracted or
abutment portions of the casing, the said ports being duplicated-on
opposite sides of the casing, and the two ports of each pair being con-
nected by ducts or channel ways, so that the fluid may act simultaneously
on pistons on opposite sides of the hub.
A single rotary valve with two ports is applied within a suitable steam
chest surmounting the casing, the valve, steam chest, and ports being
so constructed and arranged that one and the same port in the valve
communicates with the steam in all positions of the valve, and the other
port always communicates with the exhaust.
By rotating the valve 180 degrees its steam port is brought into
connection with what was formerly the exhaust port of the piston casing
and its exhaust port with what was the steam port thereof so as to
reverse the engine. An intermediate position of the valve cuts off
steam from both ports, and thus stops the engine.
It is.decmed preferable that the sliding pistons shall be stationary
or nearly so with respect to the rotary hub while receiving effective
pressure from the fluid. While sliding in and out, they are either

page_text: removed from pressure, or the construction of the interior of the
casing causes them to receive an equal or balancing pressure on both.
sides.
When antifriction rollers are applied to the pistons they are pre-
ferably. set in recesses at a little distance from 'the ends of the pistons,
so that the spindles may have bearings on both sides of the rollers.
To apply springs to the pistons as a medium through which the cams
act to press them out, each of the said pistons has at the centre of its
back a projection bearing against the centre of a flat or semi-elliptic
steel spring, the ends of which bear upon the peripheries of the
stationary cams through the medium of shoes, which shoes are formed
with flanges embracing the ends of the piston, so as to keep the parts
in proper relative positions. The pistons may be made of thin plates of
steel. The seats or recesses in which they slide within the hub aré
lined with "Babbit or other suitable soft metal, which may be run in
around the pistons while they are retracted within their seats.
"
For purposes of lubrication the rotary shaft is made hollow, com,
municating through a tube and stuffing box with an oil cup or
reservoir. The shaft is perforated near its ends to supply oil to its own
bearings in the centre of the stationary cams inside the heads of the
casing, and at the mid length of the shaft it is perforated to supply oil
to the valves. The lubricant supplied through these apertures is by
centrifugal and capillary force distributed to all the moving parts.
The Invention will be more clearly understood from the following
description with reference to the accompanying Drawings, which show
the improvements under various modifications. These modifications
will suggest others under which the Invention may be applied without
departing from its essential features.
DESCRIPTION OF THE DRAWINGS.
Figure 1 is an end elevation (partly in section) of a rotary engine
with one head removed; Figure 2 is a longitudinal section thereof;
Figure 3 is an external view of one of the heads; Figure 4 represents a
transverse section of the same; Figure 5 is an inside view of one of the
heads; Figure 6 is a detached side view of a piston; Figure 7 is an
end view of the same; Figure 8 is a face view of the valve; Figure 93
is a transverse section, near one end, of a rotary engine of modified

page_text: construction illustrating the same Invention;. Figure 10 is a central
.transverse section of the same on the line a, a, Figure 13; Figure 11 is
an inside view of a head of the casing showing in outline the stationary
cam and the parts communicating with the supplementary steam duct
or channel herein-after described; Figure 12 is an external view of one of
the heads; Figure 13 is a longitudinal section of the engine on the
line b, b, Figure 9; Figure 14 is a perspective view of a spring shoe;
Figure 15 is a view of a piston; Figure 16 is a plan of the valve seat;
Figure 17 is a representation of the face of the valve.
Figure 14, 15, 16, and 17 are on a larger scale than the other
Figures.
.
The interior of the casing 1 may be of elliptical or ellipsoidal form in
its transverse section. At its top and bottom are ports 2º, 2, and 3ª, 3b.
While the engine is running in a forward direction 2º, 2º, are steam'
ports and the 3ª, 3b, exhaust ports. The valve seat is located at top of
the casing. To this is secured the steam chest 4, preferably of hemi-
spherical form, in which is arranged the revolving valve 5, having a
steam port 6 that connects with the inlet pipe 7, and an exhaust port 8
connecting with the exit pipe 9. In the casing 1 is arranged the rotary
hub 10 secured to the shaft 11, and having radial slots for the sliding
pistons 12, which are provided with friction rollers 13 mounted on a'
spindle 14 that runs through from end to end of the casing.
When rollers are used it is preferred to make the pistons as shown
in Figures 6 and 7, so as to give the spindle a bearing on both sides,.
thereby preventing the possibility of it becoming bent. The pistons are
operated by an eccentric hub or boss 15 within each head of the casing,
and may be provided with suitable packing at their outer ends.
1.8
.J
In the inside of the casing may also be inserted packing strips 16 and
17 which are adjusted by set screws 18. On the outer faces of the
heads 19 of the case are arranged pipes or ducts 20, connecting above"
and below with the pair of ports 2%, 2b. A similar duct connects the'
other pair of ports 3*, 3b. The object of this device is to carry the
steam from the upper port 2ª to the port 2b below, so that the steam'
may be applied simultaneously to the pistons at two sides of the rotary)
hub cylinder. The steam entering through port 6, Figure 1, drives the
piston 12 in the direction of the arrow, and at the same time passés
through the respective connection ducts 20, thus acting independently
on two of the three pistons all the time, and forming what might, be

page_text: termed a double engine.. The exhaust takes a similar course through
the opposite ports and ducts. The valve is operated by a handle or
other suitable device; when in motion a quarter turn stops the engine
and a half turn reverses it.
In the modification shown in Figures 9 and 10 the enlarged portions
of the casing 1 are concentric with the rotary hub 10, but it is con-
tracted at top and bottom so as to fit snugly to the hub at the points
marked 21. From these points recesses 22 extend each way from the
port openings. 23, 23, represent steel springs, shown more clearly in
Figure 14, having at their ends flanged shoes of steel 24, which keep
the springs in proper parallelism with the pistons 12, as the latter move
in and out, and also afford suitable bearings on the cams:
When springs 23 are
pistons 12, illustrated
The ends of
the springs 23 rest on the stationary cams 15, and their centres bear
outward against projections 25 on the rear edges of the pistons, the said
projections affording the springs room to play.
used the rollers 13 may be dispensed with. The
in Figures 9 and 13, and shown more fully in Figure 15, are made of
plate steel only sufficiently thick to bear the required pressure without
springing. Slots 26 are cast in the rotary hub 10 in such form as to
constitute suitable cavities to receive and firmly lock the " Babbitt " or
other soft metal lining 27. The pistons 12 being properly fitted are
placed in central position within their slots, and the melted metal being
run around them a close fitting lining is secured. The bottoms of the
slots 26 are cast a little larger so as to admit of the spring shoes 24
being passed through them to their position under the pistons. The
springs 23 serve to keep the pistons constantly up to their work without
unnecessary pressure or friction, and to compensate for their wear.
In Figure 13 the shaft 11 is shown hollow, and contains a tube 28
passing through a stuffing box 29, and communicating on the outside
with an oil cup or reservoir 30. 31, 31, represent holes which deliver
oil from the interior of the hollow shaft to the bearings of the said shaft
within the stationary cams or bosses 15. 32, 32, are openings delivering
oil to the sliding pistons, from which it is conducted to all the working
or wearing parts, the distribution of the oil being in each case aided by
centrifugal action.
In operation steam being admitted through the valve 5 strikes the
upper piston 12 and (through the channel way 20 in the head) the
lower piston 12 simultaneously, forcing them in the direction of the

page_text: arrows to just beyond the points previously occupied by piston 12°, 12ª,
when the steam escapes through the exhaust, the upper one directly, the
lower one through the channel way; meantime the pistons 12°, 12d, have
taken the places previously occupied by 12", 12", and are in turn under
pressure.
It will be observed that owing to the peculiar shape of the outer
cylinder the pistons do not move in their relation to the rotary hub
while they are under pressure, and that while not under pressure the
steam on the port sides has full play over their outer edges through the
recesses 22, thus balancing them while passing the abutment from port
to port. The said recesses by allowing the steam free passage over the
edges of the piston while so passing from exhaust to port entirely
prevent back pressure. The inner edges of the pistons are clasped by
the shoes 24 which rest upon the stationary cams 15, the centre of said
pistons 12 resting on the spring at 25.
The engine is lubricated perfectly from the single oil cup 30 by
gravity and centrifugal force. An "air cock" oil cup supplies oil
through the packing 29 and tube 28 to the bore in the shaft 11. Suit-
able holes 31 through said shaft furnish the bearings with oil, while the
holes 32 supply the slots and pistons with oil. The oil from the holes 32
striking on the springs first is by-them carried to the cams, and finally
to the outer cylinder. Each shaft bearing is supplied with one or more
small grooves to retain the oil, which thus forms a packing, and renders
packing boxes unnecessary.
No fly wheel is required with this engine
or with the pump.
For pumps the ports and channel ways are made larger, and the valve
at the top is omitted, induction and eduction pipes being 'attached in
its stead.
Having thus described the nature of the said Invention, and the
mode in which the same is carried into effect, I would have it under-
stood that what I claim is,―
First. The combination of the elliptical casing 1, rotary cylindrical
hub 10, and sliding pistons 12, constructed and operating as herein set
forth.
*
Second. The valve 5 with ports 6 and 8 arranged to operate sub-.
stantially as described in connection with the casing 1, rotary hub 10,
and pistons 12.

page_text: Third. The ducts or channel ways 20 connecting a pair of ports (2ª, 2",)
in the manner and for the purposes herein explained.
Fourth. The construction and relative arrangement in the casing 1 of
the abutments 21 and recesses 22 to operate in combination with the
pistons 12 in the manner and for the purposes set forth.
Fifth. The rollers 13 mounted on spindles 14, and applied within
recesses in the pistons 12 in combination with the stationary cams 15,
as explained.
Sixth. The piston springs 23 and shoes 24 operating substantially as
described in combination with the pistons 12 and cams 15.
Seventh. The metallic piston packing 27 when applied substantially
as set forth to the piston of a rotary engine or pump.
Eighth. The combination in a rotary engine or pump of the cams 15,
springs 23, shoes 24, and pistons 12, substantially as and for the purpose
set forth.
Ninth. The oil tube 28 and packing 29 in combination with a hollow
shaft 11 provided with one or more openings for applying the oil,
substantially as herein described.
In witness whereof, I, the said Benjamin Joseph Barnard Mills,
have hereunto set my hand and seal, this Thirtieth day of July,
in the year of our Lord One thousand eight hundred and seventy-
two.