IMPROVEMENTS IN HYDRAULIC ENGINES
Year: 1876

page_text: LETTERS PATENT to Henry Davey, of Leeds, in the County of York, for the
Invention of "IMPROVEMENTS IN HYDRAULIC ENGINES."
PROVISIONAL SPECIFICATION left by the said Henry Davey at the Office
of the Commissioners of Patents on the 26th October 1876.
HENRY DAVEY, of Leeds, in the County of York. "IMPROVEMENTS IN HYDRAULIC
ENGINES."
In the Specification to my Patent No. 323, of 1875, I described a combined
arrangement of cylindrical and disc valves for regulating the supply and exhaust of
water pressure to and from vertical hydraulic pumping engines.
According to one of my present improvements I arrange a similar construction of
valves in combination with horizontal hydraulic engines in the following manner :-
A cylindrical valve box communicating with the hydraulic cylinder by ports at
each end, and with the exhaust by a port between these, contains a sliding cylinder
open at one end and closed at the other by a disc valve having a stem connected to
a piston contained in a part of the valve box which is of slightly larger diameter
than the part containing the cylinder. The cylinder is formed at its open end as a
piston fitting the cylindrical valve box, an annular space being formed between the
latter and the other part of the cylinder, and this annular space which communicates
with the exhaust port is capable of being closed by bringing the closed end of the
cylinder against an annular seating in the valve box, so as to act as a cylindrical
valve. The front side of the piston of the hydraulic cylinder is made of com-
paratively small area by constructing the piston rod of large diameter and this side
of the piston is always subject to the full water pressure, which pressure is also
constantly maintained against the inner face of the before-mentioned piston
connected to the disc valve, and also in the interior of the cylindrical valve. The
back face of the valve piston on the other hand can be put alternately in com-
munication with the water pressure and with the exhaust by a cock or valve, the
position of which is reversed at each stroke of the engine by tappets or other
suitable mechanism.

page_text: From the above arrangement it will be seen that when the hydraulic piston
arrives at the end of its forward stroke and the above-mentioned cock is turned so
as to put the back of the valve piston in communication with the exhaust then the
valve piston will be moved back by the water pressure on its front face, which is of
greater area than the surface presented to the pressure by the cylindrical valve, and
the valve piston in moving will draw back with it the disc valve and cylindrical
valve. The latter in moving away from its seating will thus open the communication
between the exhaust port and the back face of the engine piston, which will
consequently be made to perform its back stroke by the constant pressure maintained
on its front face. On the reversal of the before-mentioned cock at the end of this
stroke the water pressure will be admitted to the back of the valve piston, and as
the pressure on both sides of this is now balanced the pressure on the inner end of
the cylindrical valve will cause it to close against its seat, thus closing the exhaust,
and the pressure still continuing against the inner face of the disc valve this will be
forced open, and the water pressure will now pass to the back end of the engine
piston.
According to another modification, more particularly applicable for rotary
hydraulic engines, instead of effecting the motion of the valve by the admission
and exhaust of water pressure to and from a piston connected thereto I dispense
with such piston and arrange the valves as follows:-I provide two such before-
described cylindrical valves with their annular seatings and disc valves arranged in
opposite positions, one for each end of the cylinder, and I also provide two exhaust
ports. The two disc valves are connected together by a rod which is extended
through one end of the valve box and connected to an eccentric cam or other
contrivance, by which a to-and-fro motion is imparted to the two valves suitable to
the motion of the engine piston. The space between the two cylindrical valves and
the interior thereof is always in communication with the water pressure, while the
annular space between the outside of the valves and the valve box is always in
communication with the exhaust.
When the two disc valves are pushed in one direction by the excentric the one
cylindrical valve is first moved by the water pressure so as to close the exhaust,
after which its disc valve moves away from its seat, so as to admit water pressure
to that side of the cylinder; the other disc valve then closes upon its seat, and in
continuing to move pushes open the second cylindrical valve, so as to put the other
side of the hydraulic cylinder in communication with the exhaust. This closing of
the second disc valve and opening of its cylindrical valve might be made to take
place simultaneously with the opening of the other disc valve, but by preference it
is arranged as described, so that at a certain time the two disc valves may be open
simultaneously, while the two cylindrical valves are closed, thus causing an equal
pressure to be exerted on both sides of the engine piston, which is consequently held
in equilibrio until the exhaust port is opened.
In the above arrangement the two sets of valves may be contained in two separate
chambers in the valve box, each provided with ports leading to the water pressure
supply, to the exhaust, and to the one end of the engine cylinder.
Also in the above arrangement instead of moving the valves by an excentric or
cam this may be effected by a piston in a separate cylinder, in which the water
pressure is alternately admitted and discharged, and this arrangement may also be
used with the first described system of valves in place of the piston contained in
the valve box.
Hydraulic engines constructed as above described may be advantageously
employed as portable pumping engines for use wherever a low-pressure water supply
is available, either for pumping a smaller supply of water at an increased pressure,
as for fire engines, or for pumping a larger supply of of water at a lower pressure.
Another of my improvements has for its object to enable hydraulic engines to be
worked with a variable supply of water pressure, according to the work they may
have to perform. For this purpose I arrange the piston rod to drive a crank and
fly wheel, and I cause the admission valves to be opened by eccentrics, cams, or

page_text: tappets, so that they may be kept open either during the entire stroke of the
piston, or only during a certain portion thereof, and I put the cylinder at each end
in communication with a water reservoir by a pipe provided with a check valve.
From this arrangement it will be seen that if the work of the engine be reduced
at any time then by closing the admission valve after the piston has performed a part
of its stroke the supply of motive power will be cut off, and the piston in being
made to perform the remainder of its stroke by the momentum of the fly wheel
will draw in sufficient water through the before-mentioned pipes to fill the cylinder,
so that at the return stroke there shall be no shock, such as would occur without
such supply of wåter, owing to the water pressure admitted on the other side of
the piston acting against a vacuum produced on the first-named side by the cutting
off of the supply of water under pressure.
The before-mentioned water reservoir may either be arranged below the hydraulic
cylinder or by preference I place it above and feed it with the discharge water from
the hydraulic cylinder, so that the water will enter the cylinder through the check
valves by gravity.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Henry Davey in the Great Seal Patent Office on the 25th April
1877.
HENRY DAVEY, of Leeds, in the County of York. "IMPROVEMENTS IN HYDRAULIC
ENGINES."
In the Specification to my Patent No. 323, of 1875, I described a combined
arrangement of cylindrical and disc valves for regulating the supply and exhaust of
water pressure to and from vertical hydraulic pumping engines.
According to one of my present improvements I arrange a similar construction of
valves in combination with horizontal or vertical hydraulic engines in the following
manner: A cylindrical valve box communicating with the hydraulic cylinder by
ports at each end, and with the exhaust by a port between these contains a sliding
cylinder open at one end, and closed at the other by a dise valve having a stem
connected to a piston contained in a part of the valve box which is of slightly
larger diameter than the part containing the cylinder. The cylinder is formed at
its open end as a piston fitting the cylindrical valve box, an annular space being
formed between the latter and the other part of the cylinder, and this annular space
which communicates with the exhaust port, is capable of being closed by bringing
the closed end of the cylinder against an annular seating in the valve box, so as to
act as a cylindrical valve. The front side of the piston of the hydraulic cylinder is
made of comparatively small area by constructing the piston rod of large diameter,
and this side of the piston is always subject to the full water pressure, which
pressure is also constantly maintained against the inner face of the before-mentioned
piston connected to the disc valve, and also in the interior of the cylindrical valve.
The back face of the valve piston on the other hand can be put alternately in com-
munication with the water pressure and with the exhaust by a cock or valve, the
position of which is reversed at each stroke of the engine by tappets or other suitable
mechanism.
From the above arrangement it will be seen that when the hydraulic piston
arrives at the end of its forward stroke, and the above-mentioned cock is turned so
as to put the back of the valve piston in communication with the exhaust, then
the valve piston will be moved back by the water pressure on its front face, which
is of greater area than the surface presented to the pressure by the cylindrical valve,
and the valve piston in moving will draw back with it the disc valve and
cylindrical valve. The latter in moving away from its seating will thus open the
communication between the exhaust port and the back face of the engine piston,
which will consequently be made to perform its back stroke by the constant

page_text: pressure maintained on its front face. On the reversal of the before-mentioned cock
at the end of this stroke the water pressure will be admitted to the back of the
valve piston and as the pressure on both sides of this is now balanced, the pressure
on the inner end of the cylindrical valve will cause it to close against its seat, thus
closing the exhaust, and the pressure still continuing against the inner face of the
disc valve; this will be forced open and the water pressure will now pass to the back
end of the engine piston.
According to another modification, more particularly applicable for rotary
hydraulic engines, instead of effecting the motion of the valve by the admission and
exhaust of water pressure to and from a piston connected thereto, I dispense with
such piston and arrange the valves as follows:-I provide two such before described
cylindrical valves with their annular seatings and disc valves arranged in opposite
positions, one for each end of the cylinder, and I also provide two exhaust ports.
The two disc valves are connected together by a rod which is extended through one
end of the valve box and connected to an eccentric, cam, or other contrivance by
which a to-and-fro motion is imparted to the two valves suitable to the motion of
the engine piston. The space between the two cylindrical valves and the interior
thereof is always in communication with the water pressure, while the annular space
between the outside of the valves and the valve box is always in communication
with the exhaust.
When the two disc valves are pushed in one direction by the eccentric the one
cylindrical valve is first moved by the water pressure so as to close the exhaust,
after which its disc valve moves away from its seat so as to admit water pressure to
that side of the cylinder; the other disc valve then closes upon its seat and in
continuing to move pushes open the second cylindrical valve so as to put the other
side of the hydraulic cylinder in communication with the exhaust. This closing of
the second disc valve and opening of its cylindrical valve might be made to take
place simultaneously with the opening of the other disc valve, but by preference it
is arranged as described, so that at a certain time the two dise valves may be
open simultaneously while the two cylindrical valves are closed, thus causing an
equal pressure to be exerted on both sides of the engine piston, which is consequently
held in equilibrio until the exhaust port is opened.
In the above arrangement the two sets of valves may be contained in two
separate chambers in the valve box, each provided with ports leading to the water
pressure supply, to the exhaust, and to the one end of the engine cylinder.
Also in the above arrangement instead of moving the valves by an eccentric or
cam, this may be effected by a piston in a separate cylinder in which the water
pressure is alternately admitted and discharged, and this arrangement may also be
used with the first described system of valves in place of the piston contained in the
valve box.
Hydraulic engines constructed as above described may be advantageously
employed as portable pumping engines for use wherever a low-pressure water
supply is available, either for pumping a smaller supply of water at an increased
pressure, as for fire engines, or for pumping a larger supply of water at a lower
pressure.
Another of my improvements has for its object to enable hydraulic engines to be
worked with a variable supply of water pressure according to the work they may
have to perform. For this purpose I arrange the piston rod to drive a crank and
fly wheel, and I cause the admission valves to be opened by eccentrics, cams, or
tappets, so that they may be kept open either during the entire stroke of the piston
or only during a certain portion thereof, and I put the cylinder at each end in
cominunication with a water reservoir by a pipe provided with a check valve.
From this arrangement it will be seen that if the work of the engine be reduced
at any time, then by closing the admission valve after the piston has performed a
part of its stroke the supply of motive power will be cut off, and the piston in
being made to perform the remainder of its stroke by the momentum of the fly
wheel will draw in sufficient water through the before-mentioned pipes to fill the

page_text: cylinder, so that at the return stroke there shall be no shock such as would occur
without such supply of water, owing to the water pressure admitted on the other
side of the piston acting against a vacuum produced on the first named side by the
cutting off of the supply of water under pressure.
The before-mentioned water reservoir inay either be arranged below the hydraulic
cylinder, or by preference I place it above and feed it with the discharge water
from the hydraulic cylinder, so that the water will enter the cylinder through the
check valves by gravity.
Fig. 1 represents a longitudinal section of a hydraulic pumping engine according
to my Invention.
Figs. 2 and 3, are respectively longitudinal and transverse sections to an enlarged
scale of the valve box for the hydraulic cylinder constructed and operating as I will
now describe: The hydraulic cylinder A is fitted with a trunk or differential
piston B which has its front annular arca constantly subjected to the pressure of the
working fluid supplied by a pipe b, but has its back or full area alternately sub-
jected to and relieved from that pressure by the operation of the valves in the
valve box C; this valve box is made of cylindrical form of larger diameter at the
front end than in the middle, and provided with a seating at c, and with ports c¹
communicating with the front or annular space in the cylinder A, c² communicating
with the opposite end, and c³ communicating with an exhaust or discharge passage a
and pipe a. The enlarged front part of the valve box C is fitted with a piston D,
to the rod of which is attached a disc valve d seating on the end of a hollow
cylindrical piston d' which works in the middle part of the valve box; c¹ is a
passage forming a communication with the interior of the valve box at three
points 5, c, and c, and having in it a three-way cock c8 which is worked by a lever
arm co jointed to a tappet rod c10 that slides through an eye b¹ on the trunk of the
piston B. When the cock 8 is in the position shewn in Fig. 2, there is a communi-
cation by the ports c' and c³ from the front of the valve box to the exhaust, so that
the front of the piston D is relieved from pressure whilst its back or inner side
remains subject to the working pressure. The piston D is consequently forced
forward, and having seated the valve d its continued forward movement withdraws
the cylindrical piston from the seating c, thus putting the back end of the
cylinder A in communication with the exhaust by the ports c², c. The piston B
being thus relieved from pressure on its back, the pressure of the working fluid
acting on its front annular area causes it to make its back stroke. As it approaches
the end of this back stroke, the eye b² bearing against the back tappet on the rod c¹o
causes the cock c³ to turn partly round so as to close the passage to c³ and open the
passage from c, whereby the front of the piston D becoming subject to the same
pressure as its back is put in balance. The pressure now acting on the cylindrical
piston d¹ and the valve forces them backwards seating the former on c and
opening the latter, so that the exhaust port c³ is closed and the working fluid is
admitted by the port c² to the back of the cylinder A where it acts on the full area
of the piston propelling its forwards. As the piston approaches the end of its
forward stroke, the eye b¹ bearing against the front tappet on the rod e¹0 causes the
cock c to be turned back to the position shewn in Fig. 2, whereby the piston D
is relieved of pressure on its front face, and the cycle of operations is repeated.
Fig. 4 represents a longitudinal section of the cylinder and valve box of a
hydraulic pumping engine operating as above described, the ports and passages for
the working fluid c', c, c, and the supply pipe b, and discharge pipe a being
arranged somewhat differently from the corresponding parts in Figs. 1, 2, and 3, and
the tappet rod c¹0 being jointed to the piston trunk.
Fig. 5 represents a plan partly in section of a pair of hydraulic engines working
by cranks e, e, a barrel E for hauling purposes. In this case the valve box C is

page_text: provided with the valve d and sliding cylindrical valve d, but instead of these
being worked by the action of the fluid pressure on a piston, the valve dis
attached to a rod d worked by link motion from eccentrics e¹ on the shaft of the
barrel E.
Fig. 6 represents a side view, partly in section, and Fig. 7 a plan of a pair of
hydraulic engines working a crank shaft, each engine having two cylinders A¹, A²,
fitted with a plunger B¹, common to both, the middle of this plunger being connected
by a connecting rod 63 to the crank e². Each cylinder has its valve box C fitted
with valves worked as described with reference to Figs. 1, 2, and 3, by means of a
piston D which has its upper face alternately subjected to and relieved from the
pressure of the working fluid, communication for that purpose being made through
a small pipe F to a three-way cock f, whereby the pipe F is put in connection
alternately with the supply pipe b and with a branch to the discharge. The lever
arm f¹ of the cock fis worked by tappets on a rod f2 which is moved by a lever f³
and rod f* from an eccentric f" on the crank shaft. Instead of the inner tappets
being fixed on the rod f2, the sloping sides of a triangular piece g act as tappets, this
piece while it reciprocates horizontally along with the rod f2 (to which it is connected
by a pin working in a vertical slot) being moved up or down by means of a lever g¹
connected to a governor G according as the speed of the engine varies.
From this arrangement it follows that according to the vertical position of the
triangular piece g, as determined by the governor, its sloping sides act sooner or
later in each stroke as tappets on the lever f¹, thereby cutting off the supply of
working fluid to each cylinder at an earlier or later period of the stroke of its
plunger.
In order to provide against the formation of a vacuous space in the cylinder by
the continued inovement of the plunger after the supply of working fluid is cut off,
each cylinder is provided with a suction pipe and valve H by which water is
admitted to it from a cistern H', or branch connected to the discharge pipe. As
long as the pressure in the cylinder exceeds the external pressure, the valve H
remains closed, but when the supply to the cylinder of working fluid is cut off
while the plunger continues its stroke, the valve H opens and admits fluid to fill
the cylinder, and thus is avoided the shock that would result in the back stroke of
the plunger from the existence of a vacuous space in the cylinder.
Fig. 8 represents a longitudinal section of a double valve box, operating as
described, applicable to a double-acting cylinder. In this case each end of the valve
box C is fitted with a piston D, D', connected to a disc valve d, d³, and there are
two hollow cylindrical valves d², d³, seating respectively at c, c¹. The middle
space H of the valve box is supplied with the working fluid; there are two
ports h, h¹, each leading to one end of the working cylinder, and there are two exhaust
ports h2, h3. There are passages 2, 3, provided with a cock k¹, by turning which
partly round either of the passages 2 or 3 is put in communication with tbe supply
of working fluid. Thus when, the one piston, for example D, is relieved while the
other D' is subjected to pressure, then the pressure in H acting on the annular area
of d², and on the circular area of d seats d² on the seating c, so closing the exhaust
port h2, and opens d, admitting fluid from H to the port h leading to the one end of
the cylinder. At the same time the excess of pressure on the outer face of D¹ forces
it inwards, closing the valve d¹ so as to cut off the supply from H to h¹, and
unseating d³ so as to open communication from the opposite end of the working
cylinder by the port to the discharge port h³.
When the cock k¹ is turned
partly round the action on the pistons D, D¹, is reversed, as may be readily
understood. By suppressing the pistons D, D¹, the cock k¹ and passages k² and k³,
and extending the rod K which connects the valves d, d', through a stuffing box in
the end of the valve box, and connecting it, either directly or by tappets, to an
eccentric, cam, or the like, the valves may be worked from a rotating shaft. By
somewhat lengthening the part of the rod K intervening between the two disc
valves d, d, either of these will be opened a little before the other is closed, both
the annular valves d², d, being nevertheless both seated in the first place.

page_text: Having thus described the nature of my said Invention, and in what manner the
same is to be performed, I claim,―
First. In a hydraulic engine having a differential piston subjected to the constant
pressure of the working fluid on the annular area of its one face, alternating the
supply and discharge of the working fluid to one end of the cylinder, so as to act
on the other face of the piston by means of a valve arrangement wherein a sliding
hollow cylindrical valve and a disc valve combined therewith are caused to alternately
open and close communication between the cylinder port and the supply and
discharge ports, substantially as herein described with reference to Figs. 1 to 7 of
the accompanying Drawings.
Second. In a double-acting hydraulic engine alternating the supply and discharge
of the working fluid at the opposite ends of the cylinder by means of a valve
arrangement consisting of a double set of valves of the kind referred to in the
preceding claim, substantially as herein described with reference to Fig. 8 of the
accompanying Drawings.
Third. In a hydraulic engine applied to work a crank shaft, providing for cut off
at various points of the stroke by adapting to the cylinder a passage and check
valve, so that when the supply of working fluid is cut off while the piston continues
its stroke, the other fluid is drawn into the cylinder and the formation of vacuous
space therein is avoided, substantially as and for the purposes herein set forth.
In witness whereof, I, the said Henry Davey, have hereunto set my hand
and seal, this Twenty-third day of April, in the year of our Lord One
thousand eight hundred and seventy-seven.
HENRY DAVEY. (L.S.)