Improvements in Hydraulic Brakes for Railway and Tramway Vehicles.
Year: 1899

page_text: Date of Application, 31st Oct., 1899-Accepted, 27th Jan.; 1900
COMPLETE SPECIFICATION.
Improvements in Hydraulic Brakes for Railway and Tramway
Vehicles.
I, CAMILLE DUREY, of 17, Rue Lebrun, Paris, in the Republic of France,
Engineer, 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:-
In the hydraulic brake which forms the object of the present invention, the
motive power for actuating the gearing for operating the brake blocks is entirely
obtained from the momentum of the vehicle in movement at the precise moment
when this action becomes necessary. The brake gear of each vehicle is connected.
with the plunger of a brake cylinder communicating on the one hand with a
reservoir of liquid in constant communication with the atmosphere, and on the
other hand with a pump, the plunger of which is connected with the axle of
the vehicle by a crank or eccentric or by any other suitable means for transmitting:
movement. The suction of this pump communicates with the liquid reservoir.
During the movement of the vehicle, the plunger of the pump constantly receives
an alternating motion, but it produces the effective action of pressure of the liquid
in the brake cylinder only at the moment when it becomes necessary to actuate the
brake. The body of the pump is for this object provided with an electrically
operated mechanism, which enables the action of compression of the pump to be
started or stopped at will.
The passage of the current into this mechanism causes an interruption of the
action of the pump, that is to say, the brake ceases to act, whilst the breaking
of the circuit on the contrary causes the pump to come into action and the brake
to be applied. By simply moving a switch connecting or breaking the circuit it is
possible to obtain all that is necessary for operating the brake. It will be readily
seen that the brake will act automatically as soon as a cessation, of. current is
produced accidentally, for instance in case of the snapping of a wagon coupling
or the like. In the absence of electric current the braking operations may be
obtained by the manipulation of a mechanical part, causing or interrupting at will
the pressing action of the pump.
In the accompanying drawings, Figure 1 is a diagrammatical view of the whole
installation for a railway vehicle, each of the vehicles of a train having similar
devices with the exception of the apparatus for electrically operating them,
which is common to the whole as well as the source of electric energy. In this
diagram a indicates the brake cylinder, of which the plunger f acts upon any
ordinary system of brake gear g; b is a reservoir of liquid open to the air and
communicating by means of a pipes with the cylinder a; c is a pump, the body
of which is connected on the one hand by a pipe o with the liquid reservoir, and
on the other hand by a pipe with the brake cylinder. The plunger of the
pump is constantly set in motion by a crank rod connected to an eccentric e
keyed on the axle d of the vehicle. Finally by means of an electric switch t, the
following effects may be obtained by placing the said switch in three different
nositions

page_text: 1. The taking off of the brake. In this position the pump does not work, that
is to say, the plunger of the pump in its alternating movement does not force into
the brake cylinder, and consequently the plunger of the said cylinder is not
actuated. The cylinder at this moment communicates with the reservoir, which
avoids any unintentional application of the brake;
2. The applying of the brake. In this position the pump actuates the plunger
of the brake cylinder, and the communication of this cylinder with the reservoir
is interupted;
3. The statu quo. In this position the pump ceases to actuate the plunger of
the brake cylinder, whilst the communication between the said cylinder and the
reservoir remains interrupted. Although the brake cylinder and the pump may
be made in various forms, I preferably employ the apparatus which I will now
describe and which is shown in detail in the accompanying drawings, in which,
Figure 2 is a longitudinal section of the pump c;
Figure 3, a plan view of said pump;
Figures 4, 5 and 6 are details of the brake cylinder in longitudinal vertical
section, longitudinal horizontal section and vertical transverse section respec-
tively;
Figures 7, 8 and 9 show a mechanical apparatus capable if necessary of replacing
the action of the electric current and producing the same effects of applying
the brake, taking off the brake, and the statu quo.
By reason of the pressures to be reached, the pump has a plunger piston. It
may however be any other suitable one, but should be preferably a double acting
one. It has a double action in forcing the liquid, which enables a more regular
current of liquid to be obtained.
The body of the pump is composed of two parts 1 and 2. The front part 2
corresponds to the front part of the plunger. It is closed by means of a cap 3
which is screwed down on its bearing 4 against a recessed leather washer 5 forming
a joint on the rod of the plunger. An ajutage is formed at 6, allowing a chamber 7
to be connected with the reservoir by means of a small pipe, thus allowing any
liquid which may be introduced into said chamber to be discharged without
external loss. 8 is a stuffing box gland. In the rear part a flange and four
bolts 10 enable the part 2 of the body of the pump to be screwed or pressed on
to the part 1. A leather washer 11 pressed between the parts by this screwing
forms a joint on the plunger, and separates the chambers in the front and rear
of the plunger.
The enlargement 12 in the part 1 of the body of the pump serves as a casing
for two superimposed valves 13 and 14, the lifting of which places a chamber 15
and consequently the rear part of the body of the pump in communication either
with a chamber 16 when the valve 14 lifts, or with a chamber 17 when the valve 13
lifts. The chamber 16 is in constant communication with the front part of the
body of the pump by means of passages 18 and 19. It is also in communication
with the brake cylinder by means of a pipe i fixed on a nozzle or union 20. The
chamber 17 is connected with the reservoir by a suction pipe o fixed on a nozzle
or union 21.
The chambers 16 and 17 are further capable of directly communicating with
each other by means of a series of passages 22, 23, 24 and 25. In the
cylinder 24 a spring 26 capable of being regulated by a nut 27 is arranged to
hold on its seat a ball 28 by means of a piston 29 perforated with holes. This
ball plays the part of an adjustable safety valve allowing the liquid forced by
the pump to communicate with the suction chamber when the forcing pressure
exceeds the limit determined by the pressure of the spring 26. At the lower
part of the enlargement 12 a bobbin 30 is screwed serving as support for a
solenoid.
Under the action of an electric current the solenoid attracts vertically a
cylinder 31 which encounters a rod 32 and. carries it with it in its ascending
movement. The rod 32 which is suitably guided, presses its upper end beneath the

page_text: valve 13 and holds it open when it is raised for the suction. The nipple of the
valve 13 encounters the valve 14 and maintains this latter also open when it is
raised in its turn.
33 is a block of soft iron having for its object to increase the attractive power
of the electric-solenoid on the movable mass 31, and to ensure by contact the
correct position of the latter in spite of jolts or vibration.
In the differential plunger the front and rear sections are between them as the
numbers 1 and 2 in order to obtain the same power in the out and home move-
ment of the plunger. The rod h of the plunger is pivoted to a rod 7 receiving its
movement from the axle or the wheel of the vehicle by means of an eccentric e.
In order to reduce to a minimum the consumption of liquid under pressure with
a view to a more rapid application of the brake, I construct the brake cylinder
preferably with a differential plunger. This plunger of peculiar construction
moves in a cylindrical recessed body a (Figures 4, 5 and 6). The extremity 34,
which is provided with a leather washer 35 on the face which receives the action
of the liquid, has a stud 36 sliding in a groove 37 of a sleeve 38, at the end of
which is fixed a head f for actuating the brake levers. In the interior of the
sleeve 38 a spring 39 is arranged, which tends to constantly maintain the two
ends 34 and f of the brake plunger in their position of maximum separation.
Two tubes 40 and 41 are placed within the spring in the axis of the cylinder.
The tube 40 which is outside the tube 41 is closed at one of its ends and the other
end is fixed on the part 34 of the plunger. The tube 40 and the plunger 34 are
therefore integral. The tube 41 is open at both ends, and passes through the
part 34 of the plunger with considerable friction, and carries fixed at the end
à screwed dowel 42. This dowel closes the end of the cylindrical body and forms
a joint at 43 by being screwed up by a bronze box 44 which bears externally on
the end of the cylindrical body also forming a joint at 45. The box 44 places the
interior of the tube 41 in communication with the pipe i, which pipe conveys the
liquid forced by the pump to the brake cylinder. 46 is a retaining valve prevent-
ing the liquid returning from the cylinder to the pump. At the side of the
cylindrical body at the height of the internal wall at the end, another bronze
box 47 is externally screwed. This box, Figure 6, serves for the mounting of a
valve 48, the lifting of which is produced when the brake is applied when under
the influence of the liquid coming from the pump, the piston of the brake cylinder
is displaced and draws liquid directly into the reservoir. The lifting of
said valve 48 causes the central chamber 49 and consequently the rear chamber of
the plunger of the brake cylinder to communicate with a chamber 50 which is
in constant communication with the reservoir by a pipe s fixed on a nozzle 51.
The vertical wall of the box 47 is strengthened at 52 to enable a vertical
passage 53 communicating with its lower end with the chamber 50 to be bored in
the said wall.
The box 47 is closed at its upper part by a head 54 of special form fixed by
means of bolts 55. In this head is a cylindrical basin having its axis horizontally
arranged, which basin serves fo supporting or holding the mechanism for closing
a passage 56, placing the lower part of the head and consequently the chamber 49
in communication with the interior of the basin. On the external wall of the
bottom of the basin an electro-magnet 57 is fixed, the cores of which pass through
the bottom of the basin and are capable under the action of an electric current
of attracting a piece of soft iron 58 normally held apart by an adjustable antagonis-
tical spring 59. With the attraction of the armature 58 there is produced a corre-
sponding oscillating movement of a lever 60, which lifts a ball valve 61 and
places the passage 56, that is to say the pressure chamber in communication with
the interior of the basin, in other words with the reservoir. A passage 62 places
the interior of the basin in communication with the passage 53 when the head 54
is put in position. A screwed plug 63 closes the basin and allows it to be
inspected. A valve 64 operated from the outside by means of a hand wheel 65 is
placed across the passage 53. Two passages 66 bored in the valve plug enable at

page_text: will the communication between the chamber 49 and the passage 53 to be closed
or re-established. This valve thus enables the brake to be taken off in the.
absence of electric current. This condition arises in shunting when a vehicle
is separated from the train, and in consequence of which shunting the brake of
the said vehicle has been applied automatically. This maneuvre in no way
intercepts the communication between the upper and lower parts of the passage 53,
owing to passages 67 and 68 and an annular recess 69 round the valve plug.
In a vertical plane passing through the axis of the cylindrical body, a, a
chamber 70, Figure 4, is bored in the thickness of the breech piece, said chamber.
serving to receive a valve 71 held normally on its seat by a spring capable of being
adjusted from the outside. The lifting of the valve places the rear chamber of
the plunger 34 in communication by means of passages 72, 73 and 74 with the
front part of the tube 41, when the pressure in the tube attains a given amount.
A passage 75. of very small diameter bored in the plunger 34 allows the liquid
contained between the tubes 40 and 41 to be discharged.
The cylindrical body a is closed at its front end by a head 76 forming a
joint at 77 and held by two bolts on corresponding flanges or lugs on the
cylindrical body, whilst 78 is a stuffing box.
The cylinder is provide laterally at 79, Figure 5, with a passage connected
with the reservoir by means of a pipe, thus allowing any external loss of liquid
to be avoided. On the cylindrical sleeve 38 of the sleeve plunger a ring 80 is
arranged which is formed in two parts brought together and pressed against
the said sleeve by a spring 81. This ring serves for adjustment to allow for the
wear and tear of the brake blocks.
In ordinary working, by bringing the lever of the switch (Figure 1) on the
contact 82, a flow of the current arising from a suitable source of electricity u is
introduced both in the electro-magnet 30 of the pump, and in the electro-
magnet 57 of the brake cylinder. The result of this is that the valves 13 and 14
of the pump being raised the liquid drawn up by the pipe o is not forced into the
brake cylinder. On the other hand in the brake cylinder the lever 60 is moved
over, the ball valve 61 is lifted from its seat, and communication is established
between the chamber 49 and the pipe s, that is to say, between the rear face of the
plunger and the reservoir. The brake is therefore taken off completely.
By returning the lever of the switch to the contact 83, the passage of the
current is interrupted both in the electro-magnet 30 of the pump and in the
electro-magnet 37 of the brake cylinder. The result is that on the one hand, the
valves 13 and 14 of the pump being no longer held up, the pump forces back,
through the pipe i, the liquid drawn up from the reservoir by the pipe o.. On the
other hand the ball valve 61 of the brake being pressed on its seat, all com-
munication between the chamber 49 and the pipes is intercepted. The liquid
forced back by the pump lifts the retaining valve 46 and passes through the
pipe into the tube 41 and then acts on the end of the tube 40. The whole-
plunger is thus moved forward, whilst the liquid acts only on a very small surface
of the differential plunger. In fact whilst the valve 71 remains closed, that is
to say, so long as the pressure arising from the pump does not exceed the tension
of the spring 70, the liquid of the pump does not reach the plunger 34, the latter
being displaced, draws up the liquid at the ordinary atmospheric pressure, coming
from the reservoir b, and lifting the retaining valve 48. The valve 71 is
regulated in such a way as to remain closed until the plunge of the brake
cylinder completes the necessary movement for bringing the brake blocks in
contact with the tyres of the wheels. At this moment, a great effect is produced,
because there is a shock. The valve 71 being raised, the liquid under pressure
coming from the pump by the pipe & flows by the passages 74, 73 and 72 behind
the plunger. 34, whilst the retaining valve 48 is closed.
.
If the passage of the current be again established solely in the electro magnet 30
of the pump, the latter will cease to force liquid into the brake cylinder, but as

page_text: 3. 94 and 95 both open in an intermediary position.
The rod 98 passes through a guide plug 99 and by means of a spring 100
constantly tends to press the valve 96 on its seat 94. (This is the position of the
normal working or "statu quo' as hereinbefore stated). A simple manipulation
or operation of the rod 98 allows of all the operations of applying the brake to be
carried out:
1st. The opening of the brake in normal working or statu quo" by placing
the forcing pipe of the pump in communication with the reservoir simultaneously
with the closing of 94, (the position shown in Figure 8).
2nd. The application of the brake by opening 94 and simultaneously closing 95.
3rd. The taking off of the brake by the simultaneous opening of both 94 and
95 in an intermediary position.
In ordinary working where electricity is the controlling power, this apparatus
may be maintained in the position shown in Figure 7 by a locking device 101
which is released of course when the absence of electric current makes it necessary
to employ the apparatus for operating the brake by hand as hereinbefore stated.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:-
-
1. A hydraulic brake for railway- and tramway-vehicles in which the impetus
of the vehicle in movement is utilised for actuating the plunger of a pressure
pump, the continuous movements of said pump being adapted only to send liquid
under pressure into the brake cylinder at the commencement of the moment
when the brake is to be applied by the breaking of the circuit in an electric device
for lifting the suction valve of the pump, or by operating by hand a three way
distributor substantially as herein before set forth.
2. In a hydraulic brake such as hereinbefore described, a pressure pump having
a plunger piston and double acting, substantially as described and shown in
Figures 2 and 3 of the accompanying drawings.
3. In a hydraulic brake such as hereinbefore described, a brake cylinder having
a differential piston or plunger 35 and 40 and regulating valves 70 and 71 allowing
a reduction of the consumption of liquid, or of the period of approach for the initial
movement of the piston, intended to bring the brake blocks in proximity to the

page_text: wheels, substantially as herein before described, and shown in Figures 4, 5 and 6
of the accompanying drawings.
4. In a hydraulic brake such as hereinbefore described, a three way distributor
enabling the apparatus to be mechanically operated in case of the electric operat-
ing apparatus being non-working or being unused, substantially as hereinbefore
described and shown in Figures 7 and 8 of the accompanying drawings.
5. The general construction and combination of parts taken as a whole forming
the improved hydraulic brake substantially as hereinbefore described and
illustrated.
Dated this 30th day of October 1899.
W. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.