4. Description (Description shall start from next page.)
1. BACKGROUND:
1.1. Currently Air braked coaching stock of Indian Railways is provided with mechanical suspension system with hydraulic dampers. Pneumatic suspension system increases the riding comfort for passengers apart from another technical advantage that the coach height from the platform level and consequently the height of Center Buffer Couplers (CBC) between two adjacent coaches remains always the same irrespective of the pay load carried in the coach.
1.2. The Air suspension system has already been introduced in EMUs (Electric Multiple Units) /DMUs (Diesel Multiple Units), which are suburban mass transit trains. With the experience gained on EMU coaches with air suspension system, Railways are contemplating to extend this feature even to the high-speed main line long distance air braked trains.
1.3. The Air suspension system is mainly of two parts, (i.e.,) the Air Spring Control (ASC) equipment, which governs the charging and discharging of compressed air at regulated pressure levels into air springs & the second part of air suspension system is the air spring itself. The air spring also is known as 'Bellows'. Thus, the entire coach is suspended on four bellows at four corners of the coach which are inflated / deflated by the ASC equipment in proportion to the payload carried in the coach. This means the entire coach 'Floats' on the air bellows, which absorbs all the shocks due to uneven track geometry, and provides a smooth ride.

1.4. It may happen, during the normal running of the coach at high speed that one of the bellows may rupture due to various reasons such as a track side ballast hit or a cattle or animal run over leading to extensive damage to under-frame mounted equipment including the bellov/s.
1.5. When a bellow ruptures suddenly, the coach tilts dangerously to the side of ruptured bellow leading to an imbalance in the coach itself.
1.6. To over-come such dangerous tilt to one corner, there arises a requirement to provide for an equipment which will bring about a balance in the coach automatically when a bellow burst happens.
1.7. Such a safety feature already provided in the control equipment ensures that the pressure of the compressed air in the adjoining bellow also is let off by the system so that the coach level in that end is equalized to maintain a proper balance of the vehicle mass.
1.8. However, traveling at high speed, say at 140 Kmph with a coach tilted towards one side is a dangerous condition considering the passenger safety and should be brought to the notice of driver for him to take appropriate precaution during the balance of the journey.
1.9. Since entire air suspension system is purely pneumatic, there is no means to send a signal to the driver who sits in the locomotive.

1.10. Hence there is a need to actuate an automatic emergency brake in the train so that the driver will get down to investigate the cause of such emergency braking which has not been initiated by him. There should also be a system to identify the defective coach carrying the defective bellows, by means of an audio and visual indication to facilitate easy location of the defective equipment.
1.11. Once the defect is located, the driver will have to have a facility to isolate the defective equipment by closing the supply of compressed air to defective equipment and also to manually reset the emergency brake so that the train journey can be resumed, preferably at a cautious speed.
2. INVENTION OF THE PRODUCT:
2.1 FTIL has indigenously designed and invented a safety equipment designated as 'BELLOW BURST PROTECTION EQUIPMENT' (BBPE) (also called Air Spring Failure Indication Valve). This equipment is unique, novel and non-obvious. This equipment will be of great importance in enhancing safety of the passengers. The process of actuating the automatic braking of the entire train due to a bellow burst in any of the coaches in a train is a unique and novel process and is also non-obvious. It further advances the safety and security of the passengers and is of great utility for railways, not mentioning the prevention of possible equipment damage which may arise should a bellow burst situation and the consequent tilting of the coach running at high speeds lead to a derailment.

3. BBPE AND ITS FEATURES ;
3.1 The BBPE consists of
3.1.1 A Pressure Fluctuating Valve.
3.1.2 An Emergency Exhaust Valve,
3.1.3 A Whistle Valve v^ith Limiting Valve and
3.1.4 Two numbers of Indication Valves.

3.2 In Addition to the above valves, the equipment also consists of two numbers of single brake indicators for a visual indication on each side of the coach.
3.3 The valves mentioned at 3.1.1 to 3.1.4 are compactly mounted on a steel pipe bracket and housed in a protective cover.
3.4 Two such BBPE equipment sets are required per coach to indicate the condition of two sets of adjacent bellows in each of the bogies.
3.5 As desired, the design has been made in such a way that the equipment tolerates certain amount leakage of compressed air but within preset limits and actuates only if the leakage rate in the bellows exceeds the preset limit of 0.4 kg/cm square in 60 seconds, to prevent spurious and unwarranted emergency brake application in the train.

4. BBPE EQUIPMENT LAYOUT:
4.1 Piping Layout
BBPE is a combination of different valves mounted on a common pipe bracket and consist of four kinds of valves namely a Pressure Fluctuating Valve, an Emergency Exhaust Valve, a Whistling Valve v/ith Limiting Valve and tv\/o numbers of Indication Valves. The external pipe connections run through all these four types of valves. Break pipe is connected at break pipe port and the break pipe exhaust is taken out from the pipe bracket through a one inch long tube exposed at one end to the atmosphere as a precaution against direct exposure to dust. Each bellow in the bogie is connected at one port each on the pipe bracket from v/hich the pressure of the bellow is charged into the corresponding chamber inside the Pressure Fluctuating Valve. The pilot pressure exhaust is taken out at two locations into the pipe bracket, one from each Pilot Exhaust Valve. The pilot pressure being of a small volume flow rate is let off directly to the atmosphere at the rear side of the pipe bracket. The indication pressure coming from the common indication line from both the indication valves is also taken out through a separate port at the rear face of the pipe bracket and is connected to two indicators mounted near the bogie one on either side of the coach. The whistle portion discharges the compressed air thorough the whistle body to the atmosphere directly. Refer System Connection- sketch no.1
4.2 Coach Connections:
One BBPE is mounted near one bogie in the coach and is connected to the two bellows in the bogie as shown in sketch no. 3.

4.3 DESCRIPTION OF OPERATION OF BBPE 4.3.1 Charging of compressed air:
4.3.1.1 Compressed air charging into two adjacent bellows in a bogie is branched off and is connected to the pipe bracket of BBPE from where it pressurizes Chamber A and Chamber B of the Pressure Fluctuation Valve. The Pressure Fluctuation Valve is separated into chamber A and B by diaphragm A. Compressed Air charging to chamber A and chamber B of pressure fluctuating valve being at the same pressure will keep the diaphragm in its neutral position. Also the two differential springs one each in chamber A and B will also be in neutral position in this condition and nullify the forces being exerted individually.
4.3.1.2 Simultaneously brake pipe pressure at the pipe bracket of BBPE charges into emergency exhaust valve portion. The emergency exhaust valve in the pilot chamber is held on its seat by its spring. A metered hole is drilled in the emergency exhaust valve which allows the break pipe air pressure to flow into the pilot chamber side from where it is connected to two Pilot Exhaust Valve chambers, one on eacb^a^of

Diaphragm A. Since the Pilot Exhaust Valves are held by their springs to seat on the valve seats, the break pipe air pressure cannot escape from the pilot exhaust valve chamber to dov/nstream. In this condition the break pipe pressure charges to the pre-determined limit even in the BBPE working chamber and allows normal braking operation during train run.
4.3.1.3 Since the bellow pressures are same in all the four locations of the coach, and hence the chamber A and chamber B of the BBPE, the diaphragm A will continue to be in neutral position which is its mid position. The remaining passages and valves mounted on the BBPE do not receive any compressed air in this condition.
4.3.1.4 The pressure in chamber A and chamber B is also routed to the bottom side of two numbers of indication valves and is held trapped by diaphragm assembly (bottom) in each of these indication valves by its spring. The top of the indication valve receives compressed air from the opposite bellow i.e., indication valve left receives compressed air from chamber B in its top portion and vice versa. Since the pressure level in the bottom portion as well as the top portion of the indication valves is the same (that

of the bellows) the indication valves also are kept in neutral position by their springs. Refer sketch I.The remaining passages and valves mounted on the BBPE do not receive any compressed air in this condition.
4.3.2 Working of the BBPE:
4.3.2.1 The follov/ing description is made with reference to actuation of the BBPE in a bellow burst situation by considering the bursting of bellow 1 which is connected to chamber A and holds good even for the other bellow. The working of the BBPE in such a situation is depicted in Sketch - 2
4.3.2.2 When bellow 1 ruptures, compressed air contained in bellow 1 is vented into the atmosphere at a very rapid rate causing a depletion of pressure in chamber A and also on top of the diaphragm assembly (top) of the right indication valve. The pressure flow from the bellows can be seen in graphical representation in sketch no. 5. Since Bellow 2 is in good condition and has retained its compressed air pressure, pressure in chamber B will be higher than pressure in chamber A due to the rupture. The differential pressure acting on diaphragm A

will force the diaphragm A towards left side into chamber A moving the pressure plate A towards left side. This movement can happen only after the force exerted by the differential spring in chamber A is over come by the force due to the differential pressure across chamber B and A. The differential spring in each of the chambers is designed to allow the movement of the diaphragm A only after a pressure differential of 1.5Kg / cm square is set in. This phenomenon also is explained clearly in sketch no. 5 which shows that the pressure level in bellow B (healthy bellow) starts drooping initially at a slow rate and more rapidly only after a pressure differential of 1.5 kg / cm square is set in between chamber A and chamber B. When this differential pressure is reached, the differential spring in chamber A is compressed by diaphragm A, moving pressure plate A to left side. Movement of pressure plate A towards left side will cause to lift pilot exhaust valve on the left side from its seat. When the pilot exhaust valve on the left side is lifted by the pressure plate A, the break pipe air trapped in pilot exhaust valve chamber on the left side escapes downstream from where it is connected to atmosphere through pilot exhaust passage.

I i
4.3.2.3 Sudden depletion of pilot pressure in the pilot |
chamber of emergency exhaust valve causes
exhaust valve to lift off its seat compressing its
spring. This is because the metered hole made in the emergency exhaust valve cannot feed compressed air at the same flow rate as is being exhausted through the pilot exhaust port. Because of this differential flov^ across the exhaust valve, the exhaust valve is pushed up by break pipe air pressure which will always be at the higher level in such situations. When the exhaust valve is lifted, break pipe air escapes to break pipe pressure exhaust passage which is of 19 mm diameter leading to a very rapid exhaust of break pipe pressure initiating an emergency brake in the entire train.
4.3.2.4 As the driver has not applied this emergency
brake, the locomotive break system cannot
maintain the brake pipe pressure at the original
level due to the high rate of venting in the BBPE
connected to the defective bellows, thus break
pipe pressure is brought down to around 2.5 to
2.2 kg / cm square at a very rapid rate bringing
about the emergency break application in the
train. Simultaneously the right side indication
valve also is lifted up by a higher pressure in
chamber B acting under the diaphragm assembly

bottom. Since the top side of the 'diaphragm top' in the right side indication valve v^hich is connected to chamber A is depleted rapidly due to bursting of bellow 1, the diaphragm assembly bottom, experiencing a higher pressure underneath is lifted off its seat pushing the diaphragm assembly top and compressing its spring. When the diaphragm assembly bottom is lifted, pressure from bellow 2 (and hence chamber B) escapes to the bottom side of the diaphragm assembly bottom in the indication valve right from where it is charged into a common delivery passage leading to the break indicators, one connected on each side of the coach. When break indicator on that side of the coach receiving chamber B pressure is pressurized, the indicator piston moves changing the colour of indication from green to red. The green colour is indication of healthy bellows and red indication is defective bellows.
4.3.2.5 Thus in addition to an emergency braking, BBPE will turn the indicators red for visual indication. A branch from the pipe leading to indicators is taken to a limiting valve which regulates and restricts this output pressure to a maximum of 0.7 Kg / cm square. Thus irrespective of the level of pressure charging from bellow 2 into the

indicators and the limiting valve, the limiting valve charges only 0.7 Kg / cm square into the v/histle body.
4.3.2.6 The v/histle is a resonating chamber of appropriate volume and has a pre-determined size of aperture for the compressed air to flov^ over to the resonating chamber from where compressed air escapes to the atmosphere. Continuous supply of compressed air into the v/histle body causes an audio signal of pre¬determined pitch and intensity so that a constant audible v/histle is also produced to draw the attention of the driver when he walks past the train on inspection. When he detects the location of the burst bellow with the help of the visual indicators which have turned red near the bogie and also the sound of the whistle coming from the BBPE mounted near the bogie he can pin point the location of the defective bellows. Refer sketch no.2.
4.3.3 Isolation
4.3.3.1 To resume the journey after an inspection, the driver is provided with a facility to disconnect the brake pipe from the BBPE so that the pressure in the brake pipe can be recharged to

normal regime level. Such isolation facility Is kept outside the BBPE for the purpose of compacting the design. Refer to sketch no.3.
4.3.3.2 As can be seen, when a BBPE gets actuated due to a rupture in one of the two bellows to which it is connected in the coach, the other BBPE connected to the other pair of bellows in the same coach will not actuate since the chamber A and B in that BBPE are connected to two healthy bellows in the that bogie. Hence the indication and the whistle will appear only at the defective bogie.
4.3.4 Insensitivity:
4.3.4.1 Chamber A and Chamber B which receives bellow pressures from bellow 1 and bellow 2 in one bogie are connected in the pipe bracket through an orifice drilled in a choke of a predetermined size. If there is a leakage in one of the bellows, (i.e) either bellow 1 or bellow 2 alone, air in chamber A or chamber B will start depleting at a rate equal to the leak rate. Since the choke will also start feeding air from healthy bellow to the leaky bellow at the same rate, pressure in both the bellows will deplete uniformly though the leak is seen in ong hpjlow.

This leak rate which is normally unavoidable in any pneumatic system is decided by the feeding capacity of the insensitive choke. This pressure depletion at a uniform and a slov/ rate is shown in graphical representation in sketch no. 6 in which the single graph which represents both the bellow pressures droops at a uniform rate over time.
4.3.4.2 If a bellow ruptures, the rate at which the
pressure in chamber connected to that bellow is
depleted is so high, the insensitivity choke
cannot feed the air pressure from the healthy
bellow into the defective bellow side. This leads
to a big differential between pressures in
chamber B and chamber A required to actuate
the BBPE. When the indication valve is lifted
and allows the healthy bellow pressure to
escape to the indicating pipe line part of it is
branched off into the underside of a diaphragm
assembly 'A' and 'B' fixed on top of each pilot
exhaust valve. The pressure exerts sufficient
force on the under side of the diaphragm
assemblies on both sides of pilot exhaust valve
and keeps the pilot exhaust valve lifted
continuously. These valves are held lifted as
long as compressed air from the healthy bellow
(bellow 2 in this illustration) is above 1 Kg / cm
square. /^^^^^^

4.3.4.3 This feature is devised to make sure that the pilot pressure from the pilot chamber of the exhaust valve cannot be built up again until break pipe itself is isolated from BBPE. When pilot pressure cannot be built up the exhaust valve, under the influence of break pipe pressure underneath is kept lifted causing the discharge of compressed air to the atmosphere continuously. Thus an emergency break application once initiated by the BBPE will not get reset until a corrective action is taken by the driver coming on examination. Even in such cases when a corrective action is taken by the driver, he can only release the emergency break application but he cannot suppress the whistle nor the colour indication which will continue to be present until the defective bellow is replaced or the compressed air in the entire air suspension system is purposely discharged by the driver.

5. Claims (not applicable for provisional specification. Claims should start with the preamble - "I/We claim" on separate page)
5.1 We claim patent for BBPE equipment comprising of a Pressure Fluctuating Valve, an Emergency Exhaust Valve, a Whistling Valve with Limiting Valve and two numbers of Indication Valves and the insensitivity choke.

5.2 We claim patent for the piping connections to BBPE as shown in sketch no.3.
5.3 We claim patent for the process of automatic actuation of emergency brakes in the train by which the train is brought to a stop.
5.4 We claim patent to the process of audio and visual indication of the location of the burst bellow and the method of isolation of the brake pipe to that BBPE of that bogie.
5.5 We claim patent on the process of manual release of brakes to facilitate resumption of the journey.
5.6 We claim patent to the process of preventing spurious and unwarranted emergency brake application by any BBPE, due to unavoidable system leakages which are common in any pneumatic system, upto the safe predetermined leak rate of 0.4 kg / cm square in 60 seconds.
5.7 We claim patent for application of emergency brake when the leak rate of 0.6 kg / cm square or more in 6 seconds.
5.8 We claim patent to the process of controlling the audio indication (Whistle) to a tolerable pitch and sound power level, so as not to cause any panic to the passengers occupying that coach with the defective bellow, but of sufficient intensity to attract the attention of the driver even from a distance of 2 coach lengths.

5.9 We claim patent to the process used to maintain a constant and steady pitch in the whistle sound to make it distinctly audible to the driver on investigation round.
5.10 We claim patent to the process used to keep the emergency brake application 'retained' until the driver can reset it.
5.11 We claim patent to the process used to 'detect and confirm' the true bellow burst situation before an emergency brake application is initiated by BBPE thereby avoiding spurious brake applications due to normal pressure fluctuations encountered in dynamic running conditions of the train.
5.12 We claim patent to the process adopted in the design to actuate the indication valves through a non contact method but only by measurement of forces created by the rate of flow of compressed air and the areas on which compressed air acts, thus eliminating all type of mechanical interconnecting levers between pressure fluctuating valve and the indication valves.
5.13 We claim patent to the process adopted in the design to retain the indication and the whistle sound though the driver has reset the emergency brake application to resume the journey, until either the defective bellow is replaced or until the driver has discharged the compressed air in the air suspension system to atmosphere before resumption of the journey.

6. Date ft Signature (to be given at the end of last page of specification)
7. Abstract of the invention (to be given along with complete specification on
separate page) Attached separately.

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