Improvements in Car Brake Systems.
Year: 1894

page_text: Date of Application, 24th July, 1894-Accepted, 25th Aug., 1894
COMPLETE SPECIFICATION.
Improvements in Car Brake Systems.
Walnut &
I, HENRY AUGUSTUS CLARK, Manufacturer residing corner
Harvey Streets, Brookline, Norfolk County, State of Massachusetts, United
States of America, 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 :-
This invention relates to a system for operating brakes, and consists in providing
a system entirely closed, or in other words, a system which neither discharges into
the air or is subject to atmospheric influences.
My invention is embodied in a permanently closed system, which includes two
vessels, one for pressure and the other for vacuum service, together with mechanism
by which the break-beam is operated. A further feature in my system is embodied
in a pump or other liquid-impelling agent, whereby the liquid employed as the
active agent and contained in said system, after use and return to the vacuum vessel,
is forced to enter the pressure reservoir in readiness for further service.
As before stated my system for operating brakes is preferably to contain some
liquid, as oil, but water, alcohol or other liquids may be employed with equally
efficient results. The chief characteristic, however, is embodied in the fact that
the liquid-impelling agent or pump, although in operation continuously, performs
work only at short intervals which occur after the brake system has been operated,
but normally said agent remains inactive.
The drawings accompanying this Specification represent one form of a closed
system for operating brakes as embodied in my invention.
Fig. 1 is a plan view of an apparatus adapted to operate under my system.
Fig. 2 is a section to a larger scale of the liquid-forcing agent on line 2-2,
Fig. 1.
Fig. 3 is a diagram of the apparatus as applied to a car.
Fig. 4 is a section of a tank for both vacuum and pressure service.
In said drawings the brake system is illustrated as adapted for street-car service,
more particularly for that class operated by electricity. To fully illustrate my
invention I have indicated a car axle at 2 from which extends a chain 3 to engage
a sprocket wheel 4 on a shaft 12. Within a metallic box 5, preferably closed and
dust-proof, and which is affixed beneath the car body in any suitable manner, is
placed a brake cylinder 6 in which is contained a pistou 7, the piston rod 8
extending through the end of the box and being united by a brake chain 9 to the
brake beam. Said cylinder 6 is placed longitudinally of the box by preference,
while in parallelism therewith is a pump or other liquid-forcing mechanism. This
latter is operated by means of the crank 10 on the shaft 12 on which the sprocket
wheel 4 is mounted, said crank being connected to and serving to reciprocate the
plunger 14 forming part of said pump. In lieu of the above a train of gears may
be employed; in fact divers mechanisms may be employed to operate the liquid-
forcing agent from the car axle.
The operative agency by which the brake system is rendered effective in setting,
or releasing the brakes consists in two air tight vessels 15, 16, respectively for
pressure and vacuum service. In the present instance this agency appears in the
form of a single cylinder subdivided into two chambers or reservoirs, for greater
compactness of form.
From the pressure reservoir emerges a pipe 17 with a valve 18 which valve is
to be used in case the pump is to be disconnected for repairs. In the operation
of the apparatus the valve 18 is normally open to allow the liquid stored in the

page_text: chamber 15 to pass to the brake cylinder, but the said valve should be closed prior
to disconnection of the pipe 17 to prevent the escape, aud consequent wastage, of
oil. The pipe 17 extends from said vessel 15 and terminates in a three way
valve 20, and said pipe 17 also communicates with the pressure or discharge end
of the pump. The valve 20 is united by a pipe 21 with the pressure end of the
brake cylinder and enters the latter at such a point as to allow liquid pressure to
be exerted by the brake piston in order that movement of the latter will act to set
the brakes.
Similarly from the vacuum vessel 16 leads a pipe 23 supplied with a valve 24;
but this pipe enters the pump cylinder upon the opposite side of the plunger from
the pipe 17, or on the suction side of the cylinder. Said pipe is furthermore
extended and terminates in the three-way valve 20 before alluded to. Thus it will
be readily understood that the pipe 21 serves, by the varying position of the three-
way valve, to subject the brake piston to the influence of pressure or vacuum.
The valve 20 may be operated by a lever 25 or other controlling device, and when
the said valve is in the position shown in Fig. 1 the pipe 21 is closed to both the
pressure and vacuum vessels. Such would be the usual position when it is desired
to have the brake beam entirely free, or when no brake action is needed. In the
operation of this system it is to be presumed that the pump is always in motion,
being so maintained by the mechanism which interconnects it with the car axle.
Furthermore it is to be assumed that the valve 24 is closed and the vacuum vessel
is to be filled completely with the liquid to be employed. In the present instance
oil for example is the operating agent. This vessel is now closed to external
influences, or is hermetically sealed to prevent admission of air, and the valve 24 is
opened, when the action of the pump will at once, or in a very short time, remove
all the liquid from the reservior 16 to the vessel 15. In this way a vacuum will be
established in one and a high pressure created in the other vessel. The system is
now in readiness for use, in fact it may be operated at any time so long as pressure
exists in the vessel 15.
If the brakes are now to be set the three-way valve 20 is axially shifted until
communication is established between the pipes 17 and 21, when liquid under
pressure passes into the brake cylinder and moves the piston a certain distance.
This movement it is evident may be controlled according to the amount of liquid
allowed to pass into the brake cylinder. When the desired brake effect is
established the valve 20 is closed, this brake effect is now continued while the valve
remains closed, or it may be increased or it may be diminished. If the latter effect
is desired and the brakes are to be released, the lever 25 is shifted until the pipes 23
and 21 are connected. In this event the liquid in the brake cylinder rushes into
the vacuum vessel or chamber. This return of the liquid (which has been employed
in setting the brakes) from the brake cylinder to the vacuum vessel or chamber is
caused by the return of the brake beam and brakes to their normal positions. The
brake beams and brakes are, in practice, ordinarily returned to and maintained in
their normal positions by a spring or springs in order to hold the brake shoes away
from the wheels, and this force is utilized to retract the brake piston. Such return
movement of the brake piston ejects the oil from the brake cylinder, and as there
is a vacuum in the chamber or vessel to which it returns it is evident that the force
required for its return is only such as is necessary to cause the liquid to flow into
the said vacuum vessel or chamber, which latter may be nearly on a level with the
brake cylinder. As soon as this liquid enters the vacuum vessel or chamber
the pump commences to return it to the pressure vessel or chamber. Hence it is
evident that the pump, although continuously in motion, is idle as regards the
transfer of liquid except after the brakes have been set and released.
A small tube 27 connects with the end of the brake cylinder opposite to where
the oil enters and is joined with the pipe 23 leading to the vacuum vessel. Hence
any liquid which may leak through between the walls of the brake cylinder and
the piston is easily removed and thereby allows free action of said piston which
otherwise might be obstructed or impeded. From the above description of parts

page_text: it is evident that under this closed system no loss of the operating liquid occurs
and the pump is only required to perform a duty equal to an expenditure of force
necessary to return to the pressure vessel such liquid as has been employed in
setting the brakes. This, in fact, is insignificant when compared with the piston
area upon which said liquid operates in setting the brakes.
It is evident that this brake system is comparatively noiseless, since there is no
discharge externally or into the air, as occurs in the vacuum and air brake systems
now in use and in which the exhaust from such systems is very audible. The
means for operating brakes under my system is, as has before been stated, by a
permanently closed system, there being no communication whatever with the
atmosphere, hence it is noiseless as regards exhaust. My improved system is
applicable to steam railway cars, in which case each car may be supplied with
vacuum and pressure reservoirs while a single lever system to the locomotive car
will enable all of the brakes to be readily operated by a single lever.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :
1st. A method for operating brakes, consisting in a permanently closed system
for a fluid agency comprising the following steps, firstly, in subjecting the fluid to
pressure, secondly, in then employing said agency to operate the brake mechanism,
thirdly, in returning said agency to a vacuum, and finally again subjecting such
agency to pressure, substantially as explained and described.
2nd. The apparatus for operating brakes, comprising a permanently closed
system adapted to contain a fluid agency, and consisting of a brake cylinder, a
piston, and means for interconnecting either vessel with said brake cylinder, as
fikewise mechanism by which pressure and vacuum are created, substantially as
described.
3rd. The herein described apparatus for operating brakes comprising a
permanently closed system, or a system which has no communication with the
atmosphere, and which is adapted to contain an operating liquid, said system con-
sisting of the combination with a brake cylinder, and a piston therein and which
piston is to be connected with the brake, of two vessels or chambers for pressure
and vacuum service, respectively, means for connecting either of said vessels with
said brake cylinder, a liquid-forcing device, and means whereby said liquid-forcing
device may be placed in communication with said brake cylinder, and also with
said vacuum and pressure vessels or chambers.
4th. A method for operating brakes consisting in providing a permanently closed
system for a fluid agency repetitively, in subjecting the brake piston to pressure
through the action of the fluid agent, substantially in removing said fluid agent
from the brake cylinder by the aid of a vacuum, and again returning said fluid
agent to the influence of pressure, as set forth.
5th. The herein described brake apparatus comprising the combination with a
brake cylinder provided with a piston which is to be connected with the brake beam,
of two vessels or chambers adapted, respectively, for pressure and vacuum service,
and pipes for each of said vessels or chambers to the said brake cylinder, a liquid-
forcing device or pump, suitable connections between said pump, brake cylinder
and pressure and vacuum vessels or chambers, a valve adapted to inter-connect
either of said vessels or chambers with said brake cylinder, the entire system
comprising the aboveṇamed elements being permanently closed so as to have no
communication with the atmosphere.
6th. The combination with a car axle, of a shaft operatively connected with said
car axle to be rotated thereby, a pump provided with a piston operatively connected
with said shaft, a brake cylinder provided with a suitable piston to be connected to
the brake beam, vacuum and pressure chambers or vessels having suitable con-
nections with said brake cylinder and with said pump, and a valve which may be
turned to connect said vacuum and pressure chambers with each other, through

page_text: said pump, or to connect said pressure cylinder with said brake cylinder, or to
connect the latter with said vacuum chamber or vessel, the entire system com-
prising the above named elements being permanently closed so as to have no
communication with the atmosphere.
July 3rd 1894.
HENRY AUGUSTUS CLARK,
Boston.