Improvements in Rotary Steam-engines.
Year: 1887

page_text: PROVISIONAL SPECIFICATION.
Improvements in Rotary Steam-engines.
We, FREDERICK HERBERT CRABTREE of The Rectory, Blaina, in the County of
Monmouth, Fitter and Turner, and DAVID MEREDITH of Railway Terrace, Blaina, in
the said County, Engine Driver, do hereby declare the nature of this invention to be
as follows:
Our improved engine consists of an ordinary cylinder having cast on it an upper
horizontal plane surface from flange to flange. In the centre of this plane and at
right angles with the face thereof is a longitudinal slot as long as is consistent with
the strength of the cylinder. In the cylinder on each side of the said slot a port or
passage is cast, one for steam and one for exhaust. The cylinder covers are cast with
spigots extending into the cylinder a little beyond the ends of the centre slot in the
said cylinder. The spigots are turned to fit the cylinder accurately, and faced on the
inside dead level. The face of each spigot has a vertical groove extending from the
end of the centre slot in the cylinder to a central circular recess in the cylinder cover,
formed to receive the end of the enlarged central portion of the shaft which works
between the covers. Each cover has a stuffing box and is bored out for a packing
gland and to take the shaft of the engine. A divider or abutment plate, having a jaw
on its upper edge, is planed to fit the said centre slot in the cylinder and the grooves
in the faces of the spigots on the cylinder covers, the said plate extending a little
above the plane face of the cylinder when its lower edge is resting on the shaft.
Over the centre slot in the cylinder a box is fitted having a slot to correspond with
the slot in the cylinder, the slot in the said box being wider in the centre for taking
the jaw on the divider plate. The said box has a cover fitted on the top with a
stuffing box and is bored to take the stock on the divider plate and the gland. On
the stock of the divider plate is fitted an adjustable foot for actuating the divider
plate by means of a lever rising and falling underneath the said foot. The said lever

page_text: is fixed on a weigh-shaft working in bearings fixed at each end of the cylinder. This
weigh-shaft is operated by a lever oscillating on a pin fixed in a boss on the top of
the outer face of the cylinder cover or fixed in any other suitable position. The said
oscillating lever has a slot in its upper end for taking a pin on a small connecting
rod, the other end of which rod is connected to a crank keyed on the end of the
weigh-shaft and projecting over the end of the cylinder. This crank also has a sloi
in its end for adjusting the throw as required. Near the bottom of the said oscillating
lever is pivotted a short lever by a hinge joint, the said short lever working in the
same vertical plane as the oscillating lever and, when pushed one way, abutting
against the extreme end of the said oscillating lever below the hinge joint and so
moving it, but when pushed the opposite way it does not actuate the oscillating lever
but merely swings loosely.
On the end of the short hinged lever is a small roller or disc working freely on a
pin fixed in the end of the said short lover. Under the said roller and just touching
it is a cam disc, keyed on the main shaft and having on one part of its circumference
a lug-shaped cam to answer the required cut off of the valve and lift of the divider.
This cam actuates both the valve and the divider plate. The valve is a double-beat
and has an adjustable foot fitted on its stock and is lifted by an adjustable lever fixed
on the weigh-shaft. The weigh-shaft is weighted on the opposite side to the valve so
that the said valve is always open except when the cam on the main shaft, acting on
the weigh-shaft through the oscillating lever and connections releases the valve from
the action of the lever which sustains it and allows the said valve to close. The
double-beat valve box is bolted to the cylinder at a proper distance from the weigh-
shaft according to the lift of the valvo. The main shaft has a radial leaf or piston
fixed in its centre extending from cover to cover and turned and faced to exactly fit
the cylinder. This leaf has three springs and packing bars for the purpose of keeping
the leaf steam-tight. The divider plate is kept steam-tight in the grooves of the
covers by forming a beat against the sides of the said grooves, so that it is kept
steam-tight therein by the pressure of the steam, on the bottom by its own weight
pressing on the shaft and at the top by forming a beat against the side of the centre
slot in the cylinder.
The action is as follows:-Steam being admitted through the steam port between
the leaf or piston and the divider plate, the leaf and shaft. revolve until the leaf nears
the exhaust port, the cam being so shaped as to shut the valve without lifting the
divider until the leaf has passed the exhaust port, when the divider is lifted and the
leaf or piston passes under and on until it has just cleared the bottom edge of
the steam port when the divider plate again falls, the cam having passed the lever
on the cylinder cover and the valve opens and so gives steam for another revolution.
The steam can be cut off at any part of its stroke by so shaping the cam as to release
the valve without lifting the divider plate until the leaf or piston has passed the
exhaust port, space being left between the foot on the valve stock and the lever for
lifting it when the lever which lifts the divider almost touches the foot on the divider
stock, so that the divider is always down before the valve is opened and the valve is
always shut before the divider is lifted. For reverse motion we arrange another
weigh-shaft on the opposite side of the cylinder with corresponding valve and gearing
and with the valve box fitted on what would be the exhaust port of a one-way engine.
The said weigh-shaft is operated by gearing the same as that operating the first-
mentioned weigh-shaft but arranged at the opposite end of the cylinder and worked
by a cam on that end of the main shaft. The steam pipes from each valve-box are
connected to another valve-box having a D-valve working over three passages, the
centre passage being the exhaust, and the outside passages leading to their respective
valve-boxes on the cylinder. The D-valve is made large enough to cover the centre
passages and one outside one, with a certain amount of lap to prevent leakage in case
the valve should be turned too far in reversing. Thus it the D-valve be turned so as
to cover the left and centre passages the steam being on top of the valve will enter
the cylinder through the right port and exhaust through the left into the hollow of the
D-valve and so out through the centre port into the atmosphere and if the D-valve

page_text: be turned to cover the right and centre ports it will enter the cylinder through the
left port on the opposite side of the divider and exhaust through the right, and so
reverse the motion.
Our improved rotary engine can be worked compound with two or more cylinders
coupled on the same shaft or with the low pressure cylinder working on a shaft of its
own, the two cylinders to be connected with each other for the admission and exhaust
of steam by means of one D-valve box containing five passages and a valve containing
two recesses working over the five passages, or with two ordinary D-valve boxes
with three passages and the valves with one recess.
We believe our invention will be found very advantageous for use on steam-boats
instead of the ordinary engines.
Dated this 21st day of January 1887

page_text: CUMIT DIE DI FUIFICATION.
Improvements in Rotary Steam-engines.
We, FREDERICK HERBERT CRABTREE of The Rectory, Blaina, in the County of
Monmouth, Fitter and Turner, and DAVID MEREDITH of Railway Terrace, Blaina, in
the said County, Engine Driver, 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, reference being had to the accompanying
drawings forming a part of this specification, in which :-
Figure 1 is a side elevation of our improved engine.
Figuro 2 is an end elevation of the same, and
Figure 3 is a plan of the same.
Like letters indicate like parts in all the figures.
Our improved engine consists of an ordinary cylinder A having cast on it an upper
horizontal plane surface B from flange to flange. In the centre of this plane and at
right angles with the face thereof is a longitudinal slot C as long as is consistent with
the strength of the cylinder. In the cylinder on each side of the said slot a port or
passage is cast, one Ď for steam and one E for exhaust. The cylinder covers are cast
with spigots F extending into the cylinder a little beyond the ends of the centro
slot in the said cylinder. Tho spigots are turned to fit the cylinder accurately and
faced on the inside dead level. The face of each spigot has a vertical groove G
extending from the end of the centre slot C in the cylinder to a central circular
recess in the cylinder cover, formed to receive the end of the enlarged central
portion H of the shaft I which works between the cylinder covers. Each cover has
a stuffing box and is bored out for a packing gland and to take the shaft I of the
engine. "A divider or abutment plate J having a jaw J' on its upper edge, is planed
to fit the centre slot C in the cylinder and the grooves G in the faces of the spigots F
on the cylinder covers, the said plate extending a little above the plane face B of the
cylinder when its lower edge is resting on the shaft I. Over the centre slot in the
cylinder a box or casing K is fitted having a slot K' to correspond with the slot Cin
the cylinder, the slot in the said box being wider or enlarged in the centre at K for
taking the jaw on the divider plate J. The said box or casing K has a cover L fitted
on the top, with a stuffing box L' and is bored to take the stock M on the divider
plate J and the gland. On the stock M of the divider plate is fitted an adjustable
foot M' as in figure 3, or a cap M² as in figure 2, for actuating the divider plate J by
means of a lever N rising and falling underneath the said foot or taking into the said
cap. The said lever N is fixed on a weigh-shaft O working in bearings O'. This
weigh-shaft is operated by a lever P oscillating on a pin P' fixed in a boss on the top
of the outer face of the cylinder cover or fixed in any other suitable position by which
the right motion can be attained. The upper end of the said oscillating lever P is
connected to a crank Q keyed on the end of the weigh-shaft O, by means of a
connecting rod R, the said crank projecting over the end of the cylinder. In a reversing
engin, near the loftom of the said oscillating lever P, is pivotted a short lever P² by

page_text: a hinge joint, the said short lever working in the same vertical plane as the oscillating
lever, and, when pushed one way, abutting against the extreme elbowed end P¹ of
said oscillating lever below the hinge joint, and so moving the said lever as shown in
figure 24, but when pushed the opposite way it does not actuate the oscillating lever
but merely swings loosely. On the end of the short hinged lever is a small roller or
disc working freely on a pin fixed in the end of the said short lever. In an one-
way engine the roller P³ is carried on the end of the lever Pas shown in figure 2.
Under the said roller and just touching it is a cam disc S, keyed on the main shaft,
and having on one part of its circumference a lug-shaped cam S to answer the required
cut-off of the valve and lift of the divider. This cam actuates both the valve and the
divider or abutment plate. The valve is a double-beat and has an adjustable foot T
fitted on its stock T' as in figure 3, and is lifted by the lever N fixed on the weigh-
shaft. Or instead of lifting the valve by the foot. Ta link connection T³ may be
employed as shown in figure 2. The weigh-shaft is weighted on the opposite side to
the valve so that the said valve is always open, except when the cam on the main-
shaft, acting on the weigh-shaft through the oscillating lever and connections, releases
the valve from the action of the lever N which sustains it and allows the said valve to
close. The double-beat valve box T2 is bolted to the cylinder at a proper distance
from the weigh-shaft O according to the lift of the valve. The main shaft I has a
radial leaf or piston 12 fixed in its centre extending from cover to cover and turned
and faced to exactly fit the cylinder. This leaf has three springs and packing bars
for the purpose of keeping it steam-tight against the cylinder and covers.
divider plate is kept steam-tiglit in the grooves of the covers by forming a beat against
the sides of the said grooves, so that it is kept steam-tight therein by the pressure of
the steam, on the bottom by its own weight pressing on the shaft and at the top by
forming a beat against the side of the centre slot in the cylinder.
The
The action is as follows:-Steam being admitted through the steam port D between
the leaf or piston 12 and the divider or abutment plate J, the leaf 12 and shaft I revolve
until the leaf or piston 12 nears the exhaust port E. The cam is so shaped that it then
acts upon the oscillating lever P, direct or through the short lever P2, so as to depress the
valve end of the lever N sufficiently to allow the valve to close without lifting the
divider J until the leaf 12 has passed the exhaust port, when the cam acting upon
the lever P (either direct or by means of the short lever ) lifts the divider or
abutinent plate J and the leaf or piston 12 passes under and on until it has just cleared
the bottom edge of the steam port D when the divider plate J again falls, the cam
having passed the lever P and the valve opens and so gives steam for another revolu-
tion. The steam can be cut off at any part of its stroke by so shaping the cam as to
release the valve without lifting the divider plate until the leaf or piston has passed
the exhaust port, space being left between the foot T on the valve stock T, and the
lever N for lifting it, when the other end of the said lever which lifts the divider
almost touches the foot M' on the divider stock, so that the divider is always down
before the valve is opened and the valve is always shut before the divider is lifted.
For reverse motion we arrange another weigh-shaft on the opposite side of the
cylinder with corresponding valve and gearing and with the valve box fitted on what
would be the exhaust port of an one-way engine. The said weigh-shaft is operated
by gearing the same as that operating the first-mentioned weigh-shaft but arranged
at the opposite end of the cylinder and worked by a cam on that end of the main
shaft. The steam pipes from each valve-box are connected to another valve-box
having a D-valve working over three passages, the centre passage being the exhaust,
and the outside passages leading to their respective valve-boxes on the cylinder.
The D-valve is made large enough to cover the three passages, with a certain amount
of lap to prevent leakage in case the valve should be turned too far in reversing.
Thus if the D-valve be turned so as to cover the left and centre passages, the steam
being on top of the valve will enter the cylinder through the right port and exhaust
through the left into the hollow of the D-valve and so out through the centre port
into the atmosphere and if the D valve be turned to cover the right and centre ports
it will enter the cylinder through the left port on the opposite side of the divider and

page_text: exhaust through the right, and so reverse the motion. In a reversing engine the
levers P are provided with the arrangement shown in figure 2 so that when the
lever P at one end of the cylinder is actuated by the can disc, the cam disc on
the reverse end of the shaft will throw the short lever P2 of the lever P on that end
of the cylinder out of contact with its lever P and hence the said lever will not be
actuated.
Our improved rotary engine can be worked compound with two or more cylinders
coupled on the same shaft or with the low pressure cylinder working on a shaft of its
own, the two cylinders to be connected with each other for the admission and exhaust
of steam by means of one D-valve box containing five passages and a valve containing
two recesses working over the five passages, or with two ordinary D-valve boxes with
three passages and the valves with one recess.
We believe our invention will be found very advantageous for use on steamboats
instead of the ordinary engines.
Although we have described our invention as a rotary steam engine, it may also be
used as a blower, pump or gas exhauster.
Having now particularly described and ascertained the nature of our said
Invention and in what manner the same is to be performed we declare that what we
claim is
First. The gearing for operating the divider or abutment plate and valve substan-
tially as herein set forth and as illustrated in the accompanying drawings.
Second. The arrangement for operating tbe valve independently of the divider or
abutment plate, substantially as herein set forth and illustrated.
Third. The combination and arrangement of the reversing motion and gearing
substantially as herein set forth.
Fourth. The general combination and arrangement of our improved engine
substantially as herein set forth and as illustrated in the accompanying drawings.
Dated this 19th day of October A.D. 1887.
T. N. PALMER & Co.,
Agents for the Applicants.