GB1576149A

GB1576149A - Railway train braking system

Info

Publication number: GB1576149A
Application number: GB3884977A
Authority: GB
Original assignee: Davies and Metcalfe Ltd
Current assignee: Davies and Metcalfe Ltd
Priority date: 1978-04-24
Filing date: 1978-04-24
Publication date: 1980-10-01

Description

(54) RAILWAY TRAIN BRAKING SYSTEM (71) We, DAVIES & METCALFE LIMITED, a British Company of Injector Works, Romiley, Stockport, Cheshire, SK6 3AE, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement:- This invention concerns a railway train braking system in which continuity of an air brake pipe in the braking system can be tested.

The braking systems concerned are of the type comprising an air brake pipe extending along the train so that variation in air pressure in the pipe provides a signal initiating brake application and release, and the brake pipe comprises a plurality of pipe sections connected one to another along the train via openable and closeable cocks.

To ensure efficient brake application and release it is essential that the variation in air pressure signalling the desired brake application or release must quickly and accurately appear in all those parts of the ~brake pipe where the variation is sensed to initiate operation of the brakes of individual rail vehicles in the train.

This necessary propagation of the signal can only occur when the brake pipe has at least a minimum degree of continuity.

In this Specification "continuity" is intended to mean that the air brake pipe is substantially free from internal obstruction which will prevent the quick and accurate propagation of the signal throughout the brake pipe.

In known braking systems of the type referred to each rail vehicle is provided with a first air brake pipe section with cocks at opposite ends. When a train is marshalled together the first brake pipe section of one vehicle is coupled by means of one or more flexible second brake pipe sections to the first brake pipe section of the adjacent vehicle, and the cocks between the two first sections are opened. If at least one of these cocks is left closed, the brake pipe does not have continuity.

Hitherto continuity of the air brake pipe has been proved by the guard at one end of the train operating his emergency brake valve to open the brake pipe to atmosphere.

Any resultant change in air pressure in the brake pipe is observed by the driver on an air pressure gauge in a driver's cab of a locomotive at the other end of the train.

From the gauge reading the driver can tell if the brake pipe has the desired continuity.

If the train only has a driver, it is desirable that continuity proving can be carried out from the locomotive alone and an object of the invention is to provide a train braking system in which this may be done.

According to the invention a railway train braking system of the type referred to comprises a non-return valve connected to one end of a length of the air brake pipe extending between the valve and a locomotive of the train, said length being the length of brake pipe whereof continuity is to be tested, and said valve being arranged to provide an obstruction to air flow through the valve in one direction along the pipe, air pressure indicator means provided on the locomotive to provide data indicative of the value of the air pressure in the length of pipe, means operable from the locomotive to create a pressure differential between part of said length of brake pipe at or adjacent to the locomotive and the valve whereby, when pipe sections forming said length are connected and the cocks between those sections are open, there is an air flow along the length and air comprising said flow passes through the valve, the arrangement being such that when the means to create the pressure differential is operated, and the pipe has the desired continuity, the pressure indicator means provides data, corresponding to desired continuity, serving as a reference, but if the data differs from said reference data this indicates either discontinuity or that the continuity is less than desired.

The invention will now be further described with reference to the accompanying formal drawings in which: Fig. 1 is a diagrammatic representation of a fragment of one embodiment of a railway train braking system formed according to the invention Fig. 2 is a diagrammatic representation of a three-way valve used in the system in Fig.

1; and Fig. 3 is a diagrammatic representation of another embodiment of a railway train braking system formed according to the invention.

With reference to Fig. 1, components of the braking system provided on a locomotive are shown within the dotted enclosure L. The air brake pipe comprises a plurality of pipe section Bl, B2, B3 on the locomotive and rail vehicles, and which pipe sections are connected one to another along the train by hoses or flexible pipe sections Fl, F2, F3, F4 via couplings Al and A2 and open cocks Cl, C2, C3 and C4. At its rear end the air brake pipe is connected via an open cock C5, a flexible pipe section F5 and a coupling A3 to a lightly spring loaded nonreturn or check valve 1 through which air can pass only in the direction indicated by arrow X. At the front end of the locomotive, the cock C6, connected to flexible pipe F6 and coupling A4, is closed.

Because the locomotive has a driver's cab at each end, certain components of the braking system thereon are duplicated for reasons readily understood by those skilled in the art. The brake pipe section B I includes therein two three-way valves 2 and 2'. Apparatus controlling flow of air into and out of the brake pipe is connected to the brake pipe section B 1, for example two manually operated driver's automatic brake valves 3 and 3' are connected to section Bl by pipes 10 and 10'. Two air pressure gauges 7 and 7' are connected to the valves 2 and 2' by pipes 11 and 11'. The brake pipe section B I is also connected to known safety equipment 4, the purpose of which need not be described further. A by-pass conduit 5 interconnecting the pipes 11 and 11' has a vacuum pump 6 connected thereto, the pump being operable from each cab.The third ports of the valves 2 and 2' are connected by pipes 12 and 12' to a valve 8, for example an electro-pneumatic pilot valve operable by means (not shown) in each driver's cab to supply control air under pressure from line 8' to the three-way valves 2, 2'.

One of these three-way valves, namely the valve 2' is shown in Fig. 2. This valve has a casing 13 with ports leading to a central part B Il and an end part B12 of the brake pipe section Bl, the pipe 11', and the pipe 12'.

A spindle 14 inside the casing has two valve members 14a and 14b. This spindle is longitudinally movable. In the normal position of the spindle, the valve member 14a closes the opening in the valve seat 15a to isolate the pipe 11' from the parts Bll and B 12 of the brake pipe section B 1, which parts are in communication through the opening in the valve seat I Sb. When pressurised air via the pipe 12' is applied to diaphragm 16, the spindle is translated so that the valve member 14b closes the opening in the valve seat 15b, thus isolating the central part B 11 of the brake pipe section Bl from the end part B12 which is now communicated with the pipe 1 l'.'When the air pressure in the pipe 12' is relieved, the spindle 14 returns to its normal position.

Prior to carrying out the continuity test it is likely the driver will have carried out the normal routine brake tests during which the brake pipe will have been checked for leakage and whether or not the flexible pipe sections Fl and F2 or F3 and F4 have been connected and the cocks Cl and C3 have been left open and the pipe section has been connected to the non-return valve 1 and the cock C5 left open. After carrying out these routine tests it may appear to the driver that the air brake pipe is satisfactory, however he cannot be sure that the whole length of the brake pipe has been tested as a closed cock may have prevented the length of pipe from that cock to the rear of the train from being tested.Provided the non-return valve has been connected to the flexible pipe section F5 on the last rail vehicle, continuity of the air brake pipe can be tested thus:-' The driver closes a brake proving switch (not shown) in the front driving cab (or moves the driver's brake valve 3' to a test position, if manually movable driver's brake valves are provided) which results in the valve 8 admitting control air under pressure from line 8' to pipes 12 and 12'. This operates the three-way valves 2 and 2' which isolate the central part B11 of the brake pipe section B1 from the end parts B12 and B13 and connects these end parts to the conduit 5 via the pipes 11 and 11'. At the same time the vacuum pump 6 is started.

The pump 6 extracts air from the brake pipe. If the brake pipe is connected up correctly down the train and all the cocks Cl ... C5 are open, air will be drawn from atmosphere through the non-return valve 1 and into the brake pipe in which the vacuum pump under these circumstances can create no more than a relatively low vacuum only.

This vacuum is indicated on the pressure gauges of which gauge 7' will be read by a driver in the front cab. If one of the cocks Cl ... C5 is left closed, then a high vacuum will be attained in the brake pipe.

Since the size of the orifice in the nonreturn valve 1 is fixed to permit no more than a low vacuum (for example 5 or 6 ins.

Hg.) to be created when continuity is satisfactory, the pressure gauges 7 and 7' will indicate two conditions: 1. High vacuum -- brake pipe obstructed somewhere along train (discontinuity).

2. Zero or low vacuum -- brake pipe correctly connected throughout train.

(Only zero vacuum may be achieved in a long air brake pipe providing high resistance to the air flow along the pipe to the vacuum pump).

The valves 2 and 2' are one convenient means for carrying out the required changeover by remote operation for continuity testing, but other types of valve may be used in their place including known manually operated valves.

The train braking system in Fig. 3 has an air brake pipe and a main reservoir pipe extending along the length of the train.

Components of the braking system on the locomotive are shown within the dotted line enclosure Ll. The air brake pipe comprises brake pipe sections bl, b2, and b3 connected one to another by flexible pipe sections fl, /2, ss, and f4 via couplings al and a2, and open cocks cl, c2, c3 and c4.

The main reservoir pipe comprises reservoir pipe sections rl, r2 and r3 connected together by flexible pipe sections pl, p2, p3, p4 via couplings dl and d2 and open cocks kl, k2, k3, k4. A check or non-return valve 21 at the rear of the train is connected to the air brake and main reservoir pipes via couplings a3 and d3, flexible pipe sections./5 and p5 and the open cocks c5 and k5. Air can only pass through the valve 21 in the direction of arrow Y. Cocks c6 and k6 at the front of the locomotive are closed.

Safety equipment 4 is connected to the brake pipe section bl. Also connected to this pipe section is apparatus for controlling the flow of air into and from the brake pipe, for example manually operated drivers automatic brake valves 24 and 24'. Two three-position valves 22 and 22' are provided in the main reservoir pipe section rl intermediate a central part rll and a respective end part r13 or r12. Air pressure gauges 23 and 23' are connected to the respective end parts r13 and r12 of the main reservoir pipe section rl. In their normal "running" positions, both of the threeposition valves 22, 22' connect the central part rll, and thus main reservoir tanks on the locomotive, with the remainder of the main reservoir pipe.

To test continuity: The driver moves the driver's brake control, in this case the handle of the valve 24, to the "emergency" position in the cab next to the train to vent the brake pipe to atmosphere. The three-position valve 22 controlled from that cab is then placed in its "vented" position to isolate the parts rll and r12 from the remainder of the main reservoir pipe and exhaust said remainder.

When the pressure in this remainder of the main reservoir pipe has fallen to zero on the pressure gauge 23, the three-position valve 22 is placed in its "isolate" position to close' the vent whilst still keeping the parts rll and r12 of the main reservoir pipe section rl isolated from the remainder of the main reservoir pipe. Now the driver's brake control, i.e. the driver's brake valve 24 is put in the "brake release" or "running" position to charge the air brake pipe in the normal way. If the train vehicles have been coupled correctly, then as the air pressure rises in the brake pipe, air will flow through the valve 21 into the main reservoir pipe which completes the circuit back to the locomotive so that the pressure recorded in the gauge 23 should rise to approximately the same value as the normal brake pipe running pressure.If the pressure on the gauge 23 does not rise to that value, there is a fault in the continuity of either the air brake pipe or the main reservoir pipe, and if the latter has no fault, then the continuity fault is in the brake pipe.

When the - three-position valve 22 is replaced in its running position, the main reservoir pipe will be charged to its full pressure. The flow of air from the main reservoir pipe to the air brake pipe is prevented by the non-return valve 21.

Once the valve 1 or 21 is in place, continuity of the brake pipe can be tested without the need for anyone to go to the rear of the train.

The valve 1 or 21 can be formed as an integral unit with a tail light for the train, or may be incorporated in a coupling carrier to which the flexible pipe sections or hoses may be attached, when not required for connection to the train.

WHAT WE CLAIM IS: 1. A railway train braking system of the type referred to comprising a non-return valve connected to one end of a length of the air brake pipe extending between the valve and a locomotive of the train, said length being the length of brake pipe whereof continuity is to be tested, and said valve being arranged to provide an obstruction to air flow through the valve in one direction along the pipe, air pressure indicator means provided on the locomotive to provide data indicative of the value of the air pressure in the length of pipe, means operable from the locomotive to create a pressure differential between part of said length of brake pipe at or adjacent to the locomotive and valve whereby, when pipe sections forming said length are connected

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. satisfactory, the pressure gauges 7 and 7' will indicate two conditions: 1. High vacuum -- brake pipe obstructed somewhere along train (discontinuity). 2. Zero or low vacuum -- brake pipe correctly connected throughout train. (Only zero vacuum may be achieved in a long air brake pipe providing high resistance to the air flow along the pipe to the vacuum pump). The valves 2 and 2' are one convenient means for carrying out the required changeover by remote operation for continuity testing, but other types of valve may be used in their place including known manually operated valves. The train braking system in Fig. 3 has an air brake pipe and a main reservoir pipe extending along the length of the train. Components of the braking system on the locomotive are shown within the dotted line enclosure Ll. The air brake pipe comprises brake pipe sections bl, b2, and b3 connected one to another by flexible pipe sections fl, /2, ss, and f4 via couplings al and a2, and open cocks cl, c2, c3 and c4. The main reservoir pipe comprises reservoir pipe sections rl, r2 and r3 connected together by flexible pipe sections pl, p2, p3, p4 via couplings dl and d2 and open cocks kl, k2, k3, k4. A check or non-return valve 21 at the rear of the train is connected to the air brake and main reservoir pipes via couplings a3 and d3, flexible pipe sections./5 and p5 and the open cocks c5 and k5. Air can only pass through the valve 21 in the direction of arrow Y. Cocks c6 and k6 at the front of the locomotive are closed. Safety equipment 4 is connected to the brake pipe section bl. Also connected to this pipe section is apparatus for controlling the flow of air into and from the brake pipe, for example manually operated drivers automatic brake valves 24 and 24'. Two three-position valves 22 and 22' are provided in the main reservoir pipe section rl intermediate a central part rll and a respective end part r13 or r12. Air pressure gauges 23 and 23' are connected to the respective end parts r13 and r12 of the main reservoir pipe section rl. In their normal "running" positions, both of the threeposition valves 22, 22' connect the central part rll, and thus main reservoir tanks on the locomotive, with the remainder of the main reservoir pipe. To test continuity: The driver moves the driver's brake control, in this case the handle of the valve 24, to the "emergency" position in the cab next to the train to vent the brake pipe to atmosphere. The three-position valve 22 controlled from that cab is then placed in its "vented" position to isolate the parts rll and r12 from the remainder of the main reservoir pipe and exhaust said remainder. When the pressure in this remainder of the main reservoir pipe has fallen to zero on the pressure gauge 23, the three-position valve 22 is placed in its "isolate" position to close' the vent whilst still keeping the parts rll and r12 of the main reservoir pipe section rl isolated from the remainder of the main reservoir pipe. Now the driver's brake control, i.e. the driver's brake valve 24 is put in the "brake release" or "running" position to charge the air brake pipe in the normal way. If the train vehicles have been coupled correctly, then as the air pressure rises in the brake pipe, air will flow through the valve 21 into the main reservoir pipe which completes the circuit back to the locomotive so that the pressure recorded in the gauge 23 should rise to approximately the same value as the normal brake pipe running pressure.If the pressure on the gauge 23 does not rise to that value, there is a fault in the continuity of either the air brake pipe or the main reservoir pipe, and if the latter has no fault, then the continuity fault is in the brake pipe. When the - three-position valve 22 is replaced in its running position, the main reservoir pipe will be charged to its full pressure. The flow of air from the main reservoir pipe to the air brake pipe is prevented by the non-return valve 21. Once the valve 1 or 21 is in place, continuity of the brake pipe can be tested without the need for anyone to go to the rear of the train. The valve 1 or 21 can be formed as an integral unit with a tail light for the train, or may be incorporated in a coupling carrier to which the flexible pipe sections or hoses may be attached, when not required for connection to the train. WHAT WE CLAIM IS:

1. A railway train braking system of the type referred to comprising a non-return valve connected to one end of a length of the air brake pipe extending between the valve and a locomotive of the train, said length being the length of brake pipe whereof continuity is to be tested, and said valve being arranged to provide an obstruction to air flow through the valve in one direction along the pipe, air pressure indicator means provided on the locomotive to provide data indicative of the value of the air pressure in the length of pipe, means operable from the locomotive to create a pressure differential between part of said length of brake pipe at or adjacent to the locomotive and valve whereby, when pipe sections forming said length are connected

and the cocks between those sections are open, there is an air flow along the length and air comprising said flow passes through the valve, the arrangement being such that when the means to create the pressure differential is operated, and the pipe has the desired continuity, the pressure indicator means provides data, corresponding to desired continuity, serving as a reference, but if the data differs from said reference data this indicates either discontinuity or that the continuity is less than desired.

2. A railway train braking system as claimed in claim 1 in which the non-return valve is arranged to allow an inflow of air into the brake pipe from atmosphere at a rate which permits exhaust means provided on the locomotive and operable therefrom to reduce air pressure in the brake pipe to less than atmospheric pressure.

3. A railway train braking system as claimed in claim 2, in which the locomotive is provided with a portion of said air brake pipe, this portion is connected with air brake pipe pressure variation means operable for creating brake application and brake release, said locomotive being provided with valve means operable from the locomotive for isolating said portion from a run of the brake pipe extending between the portion and the non-return valve and for connecting the run to a bypass conduit connected to the exhaust means, and the air pressure indicator means being connected to said conduit to indicate air pressure in the conduit.

4. A railway train braking system as claimed in claim 1, in which a reservoir pipe extends along the train from the locomotive to the non-return valve connected between the reservoir pipe and the brake pipe to allow flow of air through the non-return valve from the brake pipe to the reservoir pipe, valve means operable from the locomotive for connecting a run of the reservoir pipe between the locomotive and the non-return valve with reservoir air supply means and for isolating the run from said supply means and for venting said isolated run to atmosphere and for closing the vent, the air pressure indicator means being arranged to indicate air pressure in said run of the reservoir pipe, and means operable from the locomotive to vent the brake pipe to atmosphere and to connect the brake pipe at the locomotive with means for supplying air under pressure to said brake pipe.

5. A railway train braking system as claimed in any preceding claim in which the non-return valve is included in a coupling carrier on a rail vehicle.

6. A railway train braking system as claimed in any of claims I to 4 in which the non-return valve is included in a tail light unit of a rail vehicle.

7. A locomotive braking system of the type referred to, substantially as hereinbefore described with reference to Figs. 1 and 2, or Fig. 3 of the accompanying drawings.