IMPROVEMENTS IN LOCOMOTIVE ENGINES OPERATED BY COMPRESSED AIR, PARTS OF WHICH IMPROVEMENTS ARE APPLICABLE ALSO TO OTHER ENGINES
Year: 1881

page_text: LETTERS PATENT to Arthur William Lovell Reddie, of the Office for Patents;
+
66, Chancery Lane, in the County of Middlesex, Patent Agent, for an
Invention of "IMPROVEMENTS IN LOCOMOTIVE ENGINES OPERATED BY
COMPRESSED AIR, PARTS OF WHICH IMPROVEMENTS ARE APPLICABLE ALSO
TO OTHER ENGINES." A communication from abroad by the Pneumatic
Tramway Engine Company (Incorporated), of the City and State of New
York, United States of America.
PROVISIONAL SPECIFICATION left by the said Arthur William Lovell
Reddie at the Office of the Commissioners of Patents on the 17th October
1881.
ARTHUR WILLIAM LOVELL REDDIE, of the Office for Patents, 66, Chancery
Lane, in the County of Middlesex, Patent Agent. "IMPROVEMENTS IN LOCOMOTIVE
ENGINES OPERATED BY COMPRESSED AIR, PARTS OF WHICH IMPROVEMENTS ARE
APPLICABLE ALSO TO OTHER ENGINES. [A communication from abroad by the
Pneumatic Tramway Engine Company (Incorporated), of the City and State of-
New York, United States of America.]
In locomotives operated by compressed air it is very desirable to carry the air
in what may be called the storage-tanks or reservoirs of the locomotive at an
extremely high pressure, say, several hundred, or even one thousand pounds per
square inch, and to allow the air to pass from these reservoirs through a pressure-
reducing valve to a reservoir, which may be termed the supply reservoir, whence
it is supplied to the cylinders at a moderate working pressure, say, one hundred
pounds per square inch. Owing to the great pressure to be carried in the storage
reservoirs it is preferable to make them cylindrical and of small diameter, and it is
necessary in order to provide for carrying air enough for long trips that several
such reservoirs shall be provided.
One part of this Invention consists principally in an arrangement on the loco-
motive of such storage-reservoirs and of the supply reservoir, whereby very ample

page_text: 1
storage capacity is provided and whereby a clear view of the track ahead of the
engine is afforded to the engine driver. Two of the storage reservoirs are arranged
horizontally one above the other, and two others are arranged horizontally, one
upon each side of the first two, and about midway vertically between them. The
lower of the first mentioned two reservoirs is longer than the other three, and
projects beyond them at the rear of the locomotive, and over this projecting part
is erected the supply reservoir, which may be also used as a heater by being kept
supplied with hot water, for the purpose of increasing the expansive force of the
air. The platform for the engine-driver and the cab for the protection of the same
are in rear of the three shorter storage-reservoirs, and are situated over or project
beyond the sides of the rearwardly projecting part of the lower and longer storage-
reservoir. Besides the four storage reservoirs herein above mentioned there may
be two smaller ones of cylindrical form, the latter arranged between the former.
Another part of the Invention relates to the pressure-reducing-valve between
the storage reservoir or reservoirs and the working reservoir. After the shutting
of the throttle valve this reducing-valve is intended to be closed by the pressure
of the air in the working reservoir operating a flexible diaphragm, but the air then
remaining in the latter reservoir has not usually a high enough pressure to exert
sufficient force on the diaphragm for this purpose, and hence the reducing-valve is
not commonly closed until the pressure of air in the supply-reservoir is higher
than the ordinary working pressure, and the consequence is that the pressure in
the working-reservoir is highest when the reducing-valve is closed and the engine
at rest. The reducing valve itself is usually a balanced valve, and the necessary
resistance to the movement of the diaphragm is offered by a spring and lever. The
object of this part of the Invention is to provide means for conveniently lessening
the resistance offered to the movement of the diaphragm when the throttle valve is
shut, so that a less pressure of the reduced air in the working reservoir will serve
to close the reducing valve. To this end this part of the Invention consists in the
combination with the reducing-valve and the diaphragm and a lever bearing upon
the reducing valve stem of a spring connected with said lever, and a hand lever or
equivalent device connected with said spring, and adapted to be adjusted for
increasing or diminishing the resistance offered by said spring to the closing of the
reducing-valve. The said spring is preferably connected with the hand lever of
the throttle valve, and the resistance offered to the closing of the reducing valve
is thereby caused to be lessened by the closing of the throttle-valve.
Another part of the Invention relates to an arrangement whereby when the
main slide valve is held stationary at the middle of its stroke the cylinder and
piston of a compressed air locomotive are converted into a pump, which may be
utilized as is well known to check the speed of the engine on down grades to aid
in stopping and for utilizing the momentum of the engine in compressing air and
forcing the same into the storage reservoirs.
In carrying out this part of the Invention suction and discharge valves for air
have to be provided in the ends of the cylinder. These may be such as have been
heretofore used for the same purpose. In such use of locomotive cylinders if the
pressure exerted upon the face of the main slide valve through its ports at the end
of the stroke of the piston exceeds the pressure exerted on its back, the said valve
will be lifted or caused to chatter in working, and air will then be discharged from
the cylinder into the slide valve chest.
The object of this part of the Invention is to provide for automatically applying
sufficient pressure to the back of the main slide valve to hold it securely to its
seat when the cylinder is used as a pump, yet relieving it of all pressure except
that exerted upon it by the compressed air in its chest as soon as the throttle
valve is opened to restore the normal function of the cylinder and piston. To this
end this part of the Invention consists in the combination with the slide valve and
valve chest in an engine, whose cylinder is provided with such suction and
discharge valves of a spring-actuated-diaphragm secured in or to the back of the
slide valve chest, and a connection through which the said diaphragm exerts a

page_text: tendency to press the slide-valve to its seat. When the throttle valve is closed
and the air shut off from the slide valve chest there is nothing to counteract this
tendency, and the valve is held securely to its seat; but as soon as the throttle
valve is opened, the air thereby admitted to the slide valve chest acts upon the
diaphragm with sufficient force to overcome its spring pressure and relieve the
slide valve from such pressure. To provide for adjusting or varying the pressure
exerted upon the slide by said diaphragm a screw is employed, and the pressure
of this screw may be applied to the valve through the medium of a yoke or bridge
piece fitted to the valve."
Another part of the Invention relates to the operation of vacuum brakes applied
to compressed air locomotives or to carriages to be drawn by such locomotives, and
it consists principally in the combination with the vacuum chamber of the vacuum
brake apparatus of an engine cylinder, provided at each end with separate suction
and discharge valves for air, and so connected with said vacuum chamber as to be
capable of serving as an exhaust pump for exhausting the air from said chamber.
In applying this part of the Invention a saddle is employed as a part of the
locomotive framing to support the two engine cylinders, and in part support the
storage reservoir, and this saddle is made hollow and communicates with the
exhaust ports of both cylinders, and has attached to it the common exhaust
discharge pipe of the engine, so that the cylinders when acting as pumps draw all
their air through the hollow saddle. The said saddle has also a connection with
the vacuum chamber of the brake apparatus. There is a stop-cock in the common
exhaust-pipe,. and when the cylinders are to be employed for exhausting the said
vacuum chambers the said stop-cock is closed so that the air cannot be drawn
through the said pipe.
Another part of the Invention relates to the cut-off or expansion gear of loco-
motives worked by compressed air, this part of the Invention being not only
applicable to locomotives operated by compressed air but to those worked by
steam.
,
In carrying out this part of the Invention the cut off valves consist of slides
working on the back of the main-slide-valve. This part of the Invention consists
in producing the operation of such cut-off valves directly from the cross head of
the engine by means of a lever connected upon one side of its fulcrum with the
cut off valve stem, and a rod which is connected with said lever on the other side
of said fulcrum, and is also connected with the cross head. To provide for varying
the point of cut off two cut off valves are generally used in each valve chest, one
for each end of the cylinder, and adjusted at different distances apart to vary the
cut-off by means of a screw-stem turned by a sector gearing with a pinion provided
on the stem outside of the valve chest and operating in a well known manner.
provide for adjusting the cut off valves of the two cylinders of the locomotive
simultaneously a further improvement consists in the combination with the two
sectors of two levers, which engage with screw threads on one shaft and which are
connected with the said sectors, so that both sectors will be moved together by
turning the said shaft.
To

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Arthur William Lovell Reddie in the Great Seal Patent Office on
the 17th April 1882.
ARTHUR WILLIAM LOVELL REDDIE, of the Office for Patents, 66, Chancery
Lane, in the County of Middlesex, Patent Agent. "IMPROVEMENTS IN LOCOMOTIVE
ENGINES OPERATED BY COMPRESSED AIR, PARTS OF WHICH IMPROVEMENTS ARE
APPLICABLE ALSO TO. OTHER ENGINES." A communication from abroad by the
Pneumatic Tramway Engine Company, Incorporated, of the City and State of
New York, United States of America.
In locomotive engines operated by compressed air it is very desirable to carry
the air in what may be called the storage tanks or reservoirs of the locomotive at
an extremely high pressure, say, several hundred, or even one thousand pounds
per square inch, and to allow the air to pass from these reservoirs through a pressure
reducing valve to a reservoir, which may be termed the supply reservoir, whence
it is supplied to the cylinders at a moderate working pressure, say, one hundred
pounds per square inch.
Owing to the great pressure to be carried in the storage reservoirs it is preferable
to make them cylindrical and of small diameter, and it is necessary in order to
provide for carrying air enough for long trips that several such reservoirs shall be
provided. One part of this Invention consists principally in an arrangement on
the locomotive of such storage reservoirs and of the supply reservoir, whereby very
ample storage capacity is provided, and whereby a clear view of the track ahead
of the engine is afforded to the engine driver. Two of the storage reservoirs are
arranged horizontally one above the other, and two others are arranged hori-
zontally, one upon each side of the first two, and about midway vertically between
them. The lower of the first mentioned two reservoirs is longer than the other
three, and projects beyond them at the rear of the locomotive, and over its so
projecting part is erected the supply reservoir, which may be also used as a heater
by being kept supplied with hot water for the purpose of increasing the expansive
force of the air. The platform for the engine driver and the cab for the protection
of the same are in rear of the three shorter storage reservoirs, and are situated
over or project beyond the sides of the rearwardly projecting part of the lower
and longer storage reservoirs. Besides the four storage reservoirs herein above
mentioned there may be two smaller ones of cylindrical form, the latter arranged
between the former.
Another part of the Invention relates to the pressure reducing valve between
the storage reservoir or reservoirs and the working reservoir. After the shutting
of the throttle valve this reducing valve is intended to be closed by the pressure
of the air in the working reservoir operating a flexible diaphragm, but the air
then remaining in the latter reservoir has not usually a high enough pressure to
exert sufficient force on the diaphragm for this purpose, and hence the reducing
valve is not commonly closed until the pressure of air in the supply reservoir is
higher than the ordinary working pressure, and the consequence is that the pressure
in the supply or working reservoir is highest when the reducing valve is closed and
the engine at rest. The reducing valve itself is usually a balanced valve, and the
necessary resistance to the movement of the diaphragm is offered by a spring and
lever.
The object of this part of the Invention is to provide means for conveniently
lessening the resistance offered to the movement of the diaphragm when the
throttle valve is shut, so that a less pressure of the reduced air in the working

page_text: reservoir will serve to close the reducing valve. To this end this part of my
Invention consists in the combination with the reducing valve and the diaphragm,
and a lever bearing upon the reducing valve stem of a spring connected with said
lever, and a hand lever or other equivalent device connected with the said spring
and adapted to be adjusted for increasing or dimiuishing the resistance offered by
the said spring to the closing of the reducing valve. The said spring is preferably
connected with the hand lever of the throttle valve, and the resistance offered to
the closing of the reducing valve is thereby caused to be lessened by the closing
of the throttle valve.
Another part of the Invention relates to provision whereby when the main slide.
valve is held stationary at the middle of its stroke the cylinder and piston of a
compressed air locomotive are converted into a pump, which may be utilized, as is
well known, to check the speed of the engine on down grades to aid in stopping,
and for utilizing the momentum of the engine in compressing air and forcing the.
same into the storage reservoirs. In carrying out this part of the Invention suction
and discharge valves for air have to be provided in the ends of the cylinder. These
may be such as have been heretofore used for the same purpose.
In such use of
locomotive cylinders if the pressure exerted upon the face of the main slide valve
through its ports at the end of the stroke of the piston exceeds the pressure
exerted on its back the said valve will be lifted or caused to chatter in working,
and air will then be discharged from the cylinder into the slide valve chest.
The object of this part of the Invention is to provide for automatically applying
sufficient pressure to the back of the main slide valve to hold it securely to its seat
when the cylinder is used as a pump, yet relieving it of all pressure, except that
exerted upon it by the compressed air in the chest as soon as the throttle valve is
opened to restore the normal function of the cylinder and piston. To this end this
part of the Invention consists in the combination with the slide valve and valve
chest in an engine whose cylinder is provided with such suction and discharge
valves of a spring actuated diaphragm secured in or to the back of the slide valve
chest, and a connection through which the said diaphragmn exerts a tendency to
press the slide valve to its seat. When the throttle valve is closed and the air.
shut off from the slide valve chest there is nothing to counteract this tendency,
and the valve is held securely to its seat; but as soon as the throttle valve is opened
the air thereby admitted to the slide valve chest acts upon the diaphragm with
sufficient force to overcome its spring pressure and relieve the slide valve from such.
pressure. To provide for adjusting or varying the pressure exerted upon the slide
valve by the said diaphragm a screw is employed, and the pressure of this screw
may be applied to the valve through the medium of a yoke or bridge piece fitted
to the valve.
Another part of the Invention relates to the operation of vacuum brakes applied.
to compressed air locomotives, or to carriages to be drawn by such locomotives, and
it consists principally in the combination with the vacuum chamber of the vacuum
brake apparatus of an engine cylinder provided at each end with separate suction
and discharge valves for air, and so connected with said vacuum chamber as to be
capable of serving as an exhaust pump for exhausting the air from said chamber.
In applying this part of the Invention a hollow saddle is employed as a part of the
locomotive framing to support the two engine cylinders, and in part support the
storage reservoir, and this saddle is made bollow and communicates with the exhaust.
ports of both cylinders, and bas attached to it the common exhaust discharge pipe
of the engine, so that the cylinders when acting as pumps draw all their air through
the hollow saddle. The said saddle has also a connection with the vacuum
chamber of the brake apparatus. There is a stop cock in the common exhaust
pipe, and when the cylinders are to be employed for exhausting the said vacuum
chamber the said stop cock is closed, so that the air cannot be drawn through the
said pipe.
Another part of the Invention relates to the cut off or expansion gear of
locomotives, and this part of the Invention is not only applicable to locomotives

page_text: operated by compressed air, but to those worked by steam. In carrying out this
part of the Invention the cut off valves consist of slides working on the back of
the main slide valve. This part of the Invention consists in producing the operation
of such cut off valves directly from the cross head of the engine by means of a
lever connected upon one side of its fulcrum with the cut off valve stem, and a rod
which is connected with said lever on the other side of said fulcrum and is also
connected with the cross head. To provide for varying the point of cut off two
cut off valves are generally used in each valve chest, one for each end of the
cylinder, and adjusted at different distances apart, to vary the cut off by means of
a screw stem turned by a sector gearing with a pinion provided on the stem outaide
of the valve chest, and operating in a well known manner.
To provide for adjusting the cut off valves of the two cylinders of the locomotive
simultaneously, a further improvement consists in the combination with the two
sectors of two levers,. which engage with screw threads on one shaft, and which are
connected with the said sectors, so that both sectors will be moved together by
turning the said shaft.
In the accompanying Drawings Fig. 1 represents a side view of a locomotive for
compressed air embodying the Invention, portions thereof being broken away to
reduce the length of the Figure; Fig. 2 represents an end view thereof, the rear
end of the cab being removed to better illustrate the Invention; Fig. 3 represents
a transversely sectional diagram view of the storage reservoirs for compressed air;
Fig. 4 represents a sectional view of a reducing valve and a side view of a throttle
valve connected according to the Invention; Fig. 5 represents a plan of the reducing
valve and throttle valve with their connections; Fig. 6 represents a side view and
partial longitudinal section of one of the locomotive engine cylinders and its
appurtenances upon a larger scale and also embodying the Invention; Fig. 7
represents a transverse section of the valve chest, valves, and appurtenances upon
the dotted line, x, of Fig. 6; Fig. 8 represents a side view of one of the locomotive
cylinders with the valve chest in section, showing the mechanism employed for
adjusting the cut off valves; and Fig. 9 represents an end view of the two cylinders
and mechanism for adjusting their cut off.
Similar letters of reference designate corresponding parts in all the Figures.
In the Drawings many parts of the locomotive are omitted for the sake of
clearness, only those parts being shewn which seem to be of most importance in
describing the present Invention.
A designates the wrought iron frame of the locomotive, and B represents the
axles, the wheels being shewn in Fig. 1 in dotted outline. The locomotive
frame A with its superposed weight may be suspended from the axles by any
desirable arrangement of springs, the springs being only partly shewn in the
Drawings.
C designates the cylinders, which are bolted to the frame A and are connected
together by a saddle D in the ordinary manner.
In the locomotive here shewn four storage tanks or reservoirs E, E', E², E², are
represented, and are arranged as follows:-The tank or reservoir E, which is the
longest of the four, is arranged centrally in the width of the locomotive, and
supported upon the frame A by the cylinder saddle D and by the guide and waste
bearers D¹, D. The under side of the 'reservoir E is nearly as low as the axles B,
and hence increases the stability of the locomotive.
Immediately over the reservoir E is arranged the cab F, the floor F¹ of the cab
being somewhat below the top of the reservoir, as seen clearly in Fig. 2. The
reservoir E' is arranged directly over the reservoir E. As clearly shewn in Fig. 1,
the forward end of the reservoir E¹ is coincident with the forward end of the
reservoir E, but its rear end does not extend so far rearward as does the rear end
of the reservoir E. The two reservoirs E² are arranged one upon each side of the
two reservoirs E, E¹, and about midway vertically between them.
The two reservoirs E are slightly shorter than the reservoir E, and hence afford
plenty of standing room for the engineer upon each side of the reservoir E, and

page_text: the two reservoirs E² are so low down that the engineer may readily see over
either of them, and his view of the track in front of the locomotive is not at all
obstructed.
The reservoirs E' are supported upon the frame A by the bearer D', D³, and the
5 upper reservoir E' is supported at each side by braces D³ extending from the side
reservoirs E².
The construction and mode of operation of the main and cut off valves will now
be described, and also the mechanism employed for simultaneously shifting the cut
off valves to vary the point of cut off, such construction being shewn partly in
Figures and 2, but more clearly in Figures 8 and 9.
The pistons of the cylinders C are connected by piston rods with the cross
heads C in the usual way, and the main valve C of each cylinder is operated by a
main valve rod b in the usual way. Upon the main valve are mounted cut off
valves C, which are connected by right and left hand screw threads with the cut
off valve rod a, as in the ordinary cut off. The cut off valves Cs of each cylinder
are operated from the cross head C¹ of the engine by a lever C, which is connected
by a rod or link d with the cross head C¹.
The cut off valve stems a project through the back of the valve chest C³, and to
adjust the cut off valves C³ the stems a must be turned in one direction or the
other, according to whether it is desired to lengthen or shorten the point of cut off.
Extending transversely across the cab F is a shaft e, which is provided with a hand
wheel e, whereby it may be turned, and which is also provided with right and left
hand threads e³. The threads e engage with nuts e³ carried in the upwardly
extending arms of the bell crank levers f, and the other arms of these levers are
connected by rods g with toothed sectors h, pivotted at the back ends of the
cylinders at h', and engaging with the pinions i on the back ends of the cut off
valve. stems a. Hence it will be seen that by turning the shaft e the cut off
valves C of both cylinders are made to simultaneously approach and recede from
each other to vary the point of cut off.
The shaft e may have an intermediate bearing e, see Fig. 9, which may be
attached to any fixed part of the locomotive.
Turning now to a description of the pipe connections between the several
reservoirs and the engines, j designates a pipe which connects the two reservoirs E²
with the reservoir E', and the reservoir E' may be connected with the reservoir E
by any pipe suitably arranged.
It has been found very advantageous to pass the air, after it leaves the several
reservoirs above described and before it reaches the engines, through a boiler, tank,
or reservoir containing hot water, and G designates such a boiler, tank, or reservoir
erected upon the reservoir E within the cab F, but having no connection with said
reservoir E. From the pipe j the compressed air passes through a branch pipe k
downwards and into the tank or reservoir G, and in said branch pipe is arranged a
reducing valve G', by which the air is reduced from a pressure of several hundred
pounds, which is the pressure in the several storage reservoirs E, E¹, E, E², to
a working pressure of one hundred pounds, more or less. The air from the pipe k
passes upwards through the water in the tank G, which is heated by any suitable
means, and collects in the top of said tank, whence the supply for operating the
engines is taken by a pipe m; this pipe m, in which is located the throttle valve G,
passes downward from the top of the tank G, and from it extend branch pipes o,
which communicate through suitable passages in the saddle D with the valve
chests C of the cylinders C.
The throttle valve G may be of any suitable construction, but the reducing
valve G' is of the kind in which a diaphragm is connected with the valve and sub-
jected to the action of the air or gas on the side of the valve at which is the reduced
pressure.
The particular construction of the reducing valve which is preferably employed,
and the devices whereby it is connected with the throttle valve, will now be
described, said parts being clearly shewn in Figures 4 and 5.

page_text: As before stated, the air of high pressure enters the supply reservoir and heater G
by a pipe k, wherein is the reducing valve G¹, and the air escapes from said reservoir
through a pipe m, wherein is the throttle valve G. The air or gas is intended to pass
downwards through the pipe k, shewn in Fig. 4, and in the shell of the valve is the
valve m', which is a double valve or balance valve. Upon the stem of the valve is t
a diaphragm m², which is exposed to the action of the air or gas of reduced pressure,
and as soon as the reduced pressure becomes undesirably augmented the diaphragm m²
closes the valve m¹, more or less.
The valve m' is opened by a lever Gs, which has its fulcrum at m³, and to the
opposite end of said lever is connected a spring G*, which is connected by a link m¹
with the handle or lever Gs of the throttle valve G³, as clearly shown in Fig. 5.
The spring G may be connected with the lever Gs by a screw and nut m³ so that
the strength of the spring may be adjusted.
The spring G exerts a constant tendency on the valve m¹ to hold it open, but
when the lever G' is drawn back to open the throttle valve the spring is extended,
and hence its tensile force is increased and a greater pressure will be required
to act upon the diaphragm m³ to close the valve ml. When the throttle valve is
closed the power of the spring is less, and less pressure upon the diaphragm will
close the valve.
By this arrangement the air or gas in the supply reservoir is prevented from
rising to the working pressure when the throttle valve is closed, because a less
pressure on the diaphragm will close the balanced valve when the throttle valve is
closed than will be required when the throttle valve is open.
For the purpose of utilizing the vacant space between the four reservoirs
E, E, E, E, two small pipes or reservoirs H (shewn dotted in Fig. 2) are arranged
therein, the said reservoirs being connected with the heating tank G by a pipe kl
and the pipe k, and forming part of said tank. The relative positions of the several
reservoirs E, E¹, E. E², H, H, is clearly shewn in the diagram view, Fig. 3.
The saddle D between the two cylinders C is made hollow, and forms an exhaust
chest for the two cylinders, and from the said saddle extends the exhaust pipe I, as
seen in Fig. 2.
It has been already stated that the cylinders C may be converted into pump
cylinders when desired, and the construction of the cylinder and arrangement of
valves whereby this is rendered feasible will now be described, reference being had
particularly to Figures 6 and 7.
When it is desired to stop a locomotive the throttle is closed, and the reversing
lever is operated to bring the links to a dead point and the valve to the centre of
the stroke, so that it will cut off all communication between the valve chest C* and
the cylinder C.
In the heads of the cylinder are cavities n, which communicate by passages n'
with the main exhaust port of the engine; and n² designate suction valves through
which air drawn down the exhaust pipe I and through the passages n¹ enters the
cylinder.
The heads of the cylinder are likewise provided with discharge valves o¹, through
which air is discharged from the cylinder into cavities o³, from whence it escapes
to a pipe p which connects the cylinders C, as shewn in Fig. 2, and from thence
through a pipe g to the lower part of the supply reservoir and heater G.
The compressed air discharged by the cylinders thus goes to augment the
supply.
The supply of air for the cylinders when used as pump cylinders, instead of
being drawn down the exhaust pipe I, may be drawn from the vacuum chamber or
chambers of a vacuum brake apparatus, thus dispensing with a separate motor for
maintaining a vacuum in the said chamber or chambers. The saddle D is here
shewn as having an inlet opening S, to which may be attached a hose or pipe con-
nection leading from a vacuum reservoir upon the train, and when acting as pumps
the cylinders draw their supply of air from the saddle.
If it is desired to draw the air supply from the vacuum chamber or chambers of

page_text: a brake apparatus the exhaust pipe I should be provided with a cock or valve J,
and when it is desired to pump from the vacuum chamber of the brake apparatus
the said cock or valve is closed, so that the air cannot be drawn down the
exhaust.
When the cylinders are used as pump cylinders the throttle valve is closed, and
hence there is no considerable degree of pressure in the valve chest C*, and the
pressure of air within the cylinders would be likely to raise the valves C2 off their
seats, and cause them to chatter, the air being discharged into the valve chest
instead of into the supply reservoir and heater G.
The means whereby the valve is held to its seat while the cylinder acts as a
pump cylinder will now be described.
The valve C has upward projections C³ at the sides extending above the cut off
valves C³, and K designates a yoke or bridge piece which bears upon the top of
the projections C, as clearly shewn in Fig. 7.
The bridge-piece or yoke K has a stem or spindle K¹ projecting from it, and L
designates a diaphragm arranged in the back of the valve chest C, and exerting a
downward pressure on the yoke or bridge piece K through a collar r on the stem
or spindle K¹, as clearly shown.
When the spindle K is unscrewed from the yoke or bridge-piece K the collar
acts upon the diaphragm, and bulges it outwards or raises it, and hence the down-
ward pressure exerted by the diaphragm L may be varied as desired, and the
valve C kept to its seat and prevented from chattering. The compressed air or
gas when admitted to the valve chest C has free access to the underside of the
diaphragm L, and therefore more or less counterbalances the natural elasticity or
resilience of the said diaphragm, and nearly or quite relieves the valve C³ from the
pressure of the yoke or bridge-piece K upon it. L' designates tubes which are
arranged to conduct oil to the bearing surfaces of the yoke or bridge piece K, as
shewn in Fig. 7, and to which lubricators may be applied.
In lieu of the plate spring metal diaphragm L, a plunger or piston may be
employed, on the under side of which the compressed air in the valve chest C¹ may
act, and which is pressed down by a spring above it.
The arrangement of the cab F over the cylinder C is very advantageous,
inasmuch as the pipe-connections from the throttle valve are reduced in length,
and because of the convenient arrangement of the mechanism for adjusting the cut
off valves shewn, which would be greatly complicated if the cab were arranged at
the opposite end from the cylinders. The floor F1 of the cab is provided with trap-
doors F, as shewn in Fig. 2, which provide for very conveniently reaching the
cylinders, if necessary, for oiling or other purposes.
By this Invention a simple and effective locomotive is provided, in which the
compressed air or gas is used most economically, and which is particularly adapted
for elevated and other railways where the ordinary steam locomotive cannot be
advantageously used.
Having now set forth the nature of the said Invention of "Improvements in
Locomotive Engines Operated by Compressed Air, Parts of which Improvements
are Applicable also to other Engines," as communicated to me by my foreign
correspondents, and having explained in what manner the same may be carried
into practical effect, I wish it to be understood that I claim,-
First. In a compressed air locomotive the arrangement of the four principal
storage-reservoirs, substantially as herein described, with or without the smaller
reservoirs and the supply reservoir and heater, for the purpose set forth.
Secondly. The combination with the diaphragın, reducing valve, and the spring
for opening said valve, of a hand lever or equivalent device, to which the said
spring is connected, and which operates to increase or diminish the resistance
offered by the spring to the closing of the valve, substantially as herein described
and for the purpose set forth.
Thirdly. The combination with the diaphragm, reducing-valve, and the throttle
valve, of the spring for opening the said reducing valve connected with the hand

page_text: lever of the throttle-valve, substantially as herein described and for the purpose
set forth.
Fourthly. The combination with the locomotive cylinder, provided with inlet
and outlet valves for air so as to serve as a pump cylinder and a slide valve for
admitting a motive agent to the said cylinder when used as an engine-cylinder, of
the spring actuated diaphragm for holding the said slide valve to its seat when
the cylinder serves as a pump, substantially as herein described and for the purpose
set forth.
Fifthly. The combination with the vacuum-chamber of a vacuum-brake apparatus
of a locomotive cylinder provided at each end with suction and discharge valves for
air, whereby the said cylinder is made to serve as an exhaust-pump for exhausting
air from said chamber, substantially as herein described.
Sixtbly. The combination with the cut off valves, cut off valve stem, and cross-
head of an engine, of the lever and link or rod for connecting the said valve stem
with the said cross-head, all arranged and operating substantially as heroin described
and for the purpose set forth.
Seventbly. The combination with two engine cylinders, arranged side by side,
and each provided with cut-off slide-valves having right and left handed screw-
threads on their stems, of pinions fixed to the said cut off valve stems, toothed
sectors engaging with the said pinions, two levers, rods connecting one arm of the
said levers with the said sectors, and a screw-threaded shaft engaging with the
other arms of the said levers, and serving to oscillate the said levers and thereby
turn both the said cut off valve stems simultaneously, substantially as specified.
In witness whereof, I, the said Arthur William Lovell Reddie, have hereunto
set my hand and seal, the Fifteenth day of April, in the year of our Lord
One thousand eight hundred and eighty two.