TRAINING REPORT

AIR BRAKE SYSTEM

SUBMITTED BY

VISHAL SINGH

GB PANT ENGINEERING COLLEGE

RA 175

ACKNOWLEDGEMENT

We take this opportunity to express our sincere gratitude to the people who

have been helpful in the successful completion of our industrial training and

this project. We would like to show our greatest appreciation to the highly

esteemed and devoted technical staff, supervisors of the Diesel Loco Shed,

Tughlakabad. We are highly indebted to them for their tremendous support

and help during the completion of our training and project.

We are grateful to SSE (D.T.C.) of Diesel Loco Shed Tughlakabad and

Principal of Training School who granted me the permission of industrial

training in the shed. We would like to thanks to all those peoples who

directly or indirectly helped and guided us to complete our training and

project in the shed, including the instructors and technical officers of Diesel

Training Centre of various sections.

CONTENTS

A. Brief about training

1. Indian Railway History

2. Classification of Engines

3. Introduction – DLS TKD

4. Directly Assisting Section

B. Project Study

1. Introduction

Straight Air Brake

Working Pressures

2. Operation

3. Types

4. 28 LAV 1

5. IRAB 1

6. Layout

7. Types of Valves

8. Expressor

Working of Compressor

Working of Exhauster

9. Overhauling

General Procedures

Dismantling from Coach

Dismantling the Distributor Valve

10. Brake Binding

Effects

Causes

Measures

11. Panel Mounting

12. Development in other Countries

AWS

CWAS

13. Bibliography

.

BRIEF

INDIAN RAILWAY HISTORY

Indian Railways is the state owned railway company of India. It comes under

the Ministry of Railways. Indian Railways has one of the largest and busiest

rail networks in the world, transporting over 18 million passengers and more

than 2 million tonnes of freight daily. Its revenue is Rs.107.66 billion. Indian

Railways is the world's seventh largest commercial or utility employer, by

number of employees, with over 1.307 million employees as of last published

figures in 2013.

As for rolling stock, IR holds over 239,281 Freight Wagons, 62,924

Passenger Coaches and 9,013 Locomotives (43 steam, 5,345 diesel and 4,568

electric locomotives). The trains have a 5 digit numbering system and runs

12,617 passenger trains and 7421 freight trains daily. As of 31 March 2013,

20,884 km (12,977 mi) (31.9%) of the total 65,436 km (40,660 mi) route length

was electrified. Since 1960, almost all electrified sections on IR use 25,000

Volt AC traction through overhead catenary delivery. Indian Railways is

administered by the Railway Board. Indian Railways is divided into 16 zones.

Each zone railway is made up of a certain number of divisions. There are a

total of sixty-seven divisions. It also operates the Kolkata metro. There are

six manufacturing plants of the Indian Railways. The total length of track

used by Indian Railways is about 108,805 km (67,608 mi) while the total route

length of the network is 63,465 km (39,435 mi). About 40% of the total track

kilometre is electrified & almost all electrified sections use 25,000 V AC.

Indian railways uses four rail track gauges.

Indian Railways operates about 9,000 passenger trains and transports 18

million passengers daily .Indian Railways makes 70% of its revenues and

most of its profits from the freight sector, and uses these profits to cross-

subsidies the loss-making passenger sector. The Duronto & Rajdhani Express

are the fastest trains of India which can run at speed 130 km/hr currently.

CLASSIFICATION OF ENGINES

1. Standard Gauge dimensions

W = Broad gauge (1.67 m)

Y = Medium gauge ( 1 m)

Z = Narrow gauge ( 0.762 m)

N = Narrow gauge ( 0.610 m)

2. Motive Power

D = Diesel-electric traction

C = DC traction

A = AC traction

CA=Dual power AC/DC traction

B = Battery electric locomotive

3. Type of load or Service

M= Mixed service

P = Passenger

G= Goods

S = Shunting

U – multiple units (EMU/DMU)

R – Railcars

4. Horse Power

‘3’ for 3000 hp

‘4’ for 4000 hp

‘5’ for 5000 hp

‘A’ for extra 100 hp

‘B’ for extra 200 hp and so on.

Hence ‘WDM-3A’ indicates a broad gauge loco with diesel-electric traction.

It is for mixed services and has 3100 horsepower.

INTRODUCTION

Diesel locomotive shed is an industrial-technical setup, where repair and

maintenance works of diesel locomotives is carried out, so as to keep the

loco working properly. It contributes to increase the operational life of diesel

locomotives and tries to minimize the line failures. The technical manpower

of a shed also increases the efficiency of the loco and remedies the failures

of loco.

The shed consists of the infrastructure to berth, dismantle, repair and test

the loco and subsystems. The shed working is heavily based on the manual

methods of doing the maintenance job and very less automation processes

are used in sheds, especially in India.

The diesel shed usually has:-

Berths and platforms for loco maintenance.

Pits for under frame maintenance

Heavy lift cranes and lifting jacks

Fuel storage and lube oil storage, water treatment plant and

testing labs etc.

Sub-assembly overhauling and repairing sections

Machine shop and welding facilities.

The shed has a total berthing capacity for 17 locomotives under 4 covered

bays. The main bays are:-

1. .The subassemblies section.

2. The heavy repair and bogie section (3 berths for heavy repairs

& 2 lifting points).

3. Mail running repair bay (6 berths).

4. Goods and out of course running repair bay (6 berths). There

was one old steam shed. This shed had a capacity for berthing

4 locomotives. This shed was used for light repairs only. Now

a days, a new construction is being on for new locos of make

WDP4 locomotives.

DIRECTLY ASSISTING SECTIONS

These sections which directly assist in the maintenance work of the loco are

called directly assisting sections. These sections play an important role in the

maintenance work. The Directly assisting sections are as follows:-

1. Turbo supercharger section.

2. Expresser section.

3. Bogie section.

4. Cylinder head section.

5. Power pack section.

6. Speedometer section.

7. F.I.P section.

8. Air brake section.

9. Fuel section.

10. Pit wheel lathe section.

11. Traction motor and generator section.

PROJECT STUDY

AIR BRAKE SYSTEM

INTRODUCTION

A railway air brake is a railway brake power braking system with compressed

air as the operating medium. Modern trains rely upon a fail-safe air brake

system that is based upon a design patented by George Westinghouse on

March 5, 1868. The Westinghouse Air Brake Company (WABCO) was

subsequently organized to manufacture and sell Westinghouse's invention.

In various forms, it has been nearly universally adopted.

The Westinghouse system uses air pressure to charge air reservoirs (tanks)

on each car. Full air pressure signals each car to release the brakes. A

reduction or loss of air pressure signals each car to apply its brakes, using

the compressed air in its reservoirs.

Air brake system is most efficient and reliable braking system used to run

heavy and long trains at high speeds. It has following advantages:-

Short braking distance.

Higher braking force.

Reduced brake power deterioration.

Uniform brake power over train length.

Compact and light equipment.

Air brake system is classified as:

Single pipe air brake system

Twin pipe air brake system

Air brake system used in freight stock is single pipe graduated release air

brake system.

Straight air brake

In the air brake's simplest form, called the straight air system, compressed

air pushes on a piston in a cylinder. The piston is connected through

mechanical linkage to brake shoes that can rub on the train wheels, using

the resulting friction to slow the train. The mechanical linkage can become

quite elaborate, as it evenly distributes force from one pressurized air

cylinder to 8 or 12 wheels.

The pressurized air comes from an air compressor in the locomotive and is

sent from car to car by a train line made up of pipes beneath each car and

hoses between cars. Straight air brakes are still used on locomotives,

although as a dual circuit system, usually with each bogie having its own

circuit.

Working pressures

The compressor on the locomotive charges the main reservoir with air at

125–140 psi (8.6–9.7 bar; 860–970 kPa). The train brakes are released by

admitting air to the train pipe through the engineer's brake valve. A fully

charged brake pipe is typically 70–90 psi (4.8–6.2 bar; 480–620 kPa) for

freight trains and 110 psi (7.6 bar; 760 kPa) for passenger trains. The brakes

are applied when the engineer moves the brake handle to the "service"

position, which causes a reduction in pressure in the train pipe. In normal

braking, the pressure in the train pipe does not reduce to zero. If it does fall

to zero, (e.g., because of a broken brake hose) an emergency

brake application will be made.

OPERATION

Air Brake Freight stock is fitted with single pipe graduated release air brake

system. In single pipe, brake pipes (BP) of all wagons are connected. Also all

the cut off angle cocks are kept open except the front cut off angle cocks of

BP of leading loco and rear end cut off angle cock of BP of last vehicle.

Isolating cock on all wagons are also kept in open condition. Auxiliary

reservoir is charged through distributor valve at 5kg/cm2.

1. Charging Stage

During this stage, brake pipe is charged to 5 kg/cm2 pressure which

in turn charges control reservoir and auxiliary reservoir to 5 kg/cm2

pressure via distributor valve. At this stage, brake cylinder gets vented

to atmosphere through passage in Distributor valve.

2. Application Stage

For application of brakes, the pressure in brake pipe has to be

dropped. This is done by venting air from driver’s brake valve.

Reduction in brake pipe pressure positions the distributor valve in

such a way that the control reservoir gets disconnected from brake

pipe and auxiliary reservoir gets connected to brake cylinder. This

results in increase in air pressure in brake cylinder resulting in

application of brakes. The magnitude of braking force is proportional

to reduction in brake pipe pressure.

3. Release Stage

For releasing brakes, the brake pipe is again charged to 5 kg/cm2

pressure by compressor through driver’s brake valve. This action

positions distributor

valve in such a way that

auxiliary reservoir gets

isolated from brake

cylinder and brake

cylinder is vented to

atmosphere through

distributor valve and

thus brakes are

released.

TYPES

TYPE LOCO

BRAKE

TRAIN

BRAKE

DESIGNED

BY

FITTED IN

28 LV1 Air Vacuum WABCO WDM2,

YDM4,WDS5,

WDS6

28 LAV 1 Air Air &

Vacuum

WABCO WDM2A,WDM2C,

WDP2,WDG2,

WDP1

KNORR Air Vacuum KNORR

Brumes,

Germany

WDM3,

WDS4,ZDM3,

WDS3

IRAB Air Air RDSO WDM2C,

WDP2,WDG2,

WDM3C

CCB Air Air KNORR

Brumes,

Germany

WDG4, WDP

28 LAV 1

The braking systems that are used on loco model 28 LAV 1 are dual brake

system.

L-Loco

A-Air

V- Vacuum

SALIENT FEATURES

The salient features of 28 LAV-1 dual brake system are as under

1. Locomotive brake may be applied with any desired pressure between

the maximum and minimum and this pressure automatically

maintained in the locomotive brake cylinder against normal leakage

from then until released by the driver brake value.

2. To locomotive brakes can be applied to any level between release and

full application with either the automatic or independent brake values.

3. Emergency brake application to vent directly brake pipe and vacuum

drain pipe simultaneously is possible.

4. It is always possible to release the locomotive brakes with the train

brakes remained applied.

5. Dynamic brake interlock to prevent simultaneously application

of automatic air brakes and dynamic brakes on loco.

6. Visual indication in drives lab through airflow indicator device during

train parting or low parting or guard’s emergency valve operation

during heavily of air brake stock.

7. In the event of emergency brake application by the driver, train parting

or loco parting, the traction power shall be automatically cut off.

8. In case of parting between the locomotives, the trailing between the

locomotive and trailing stock, automatic application of locomotive

brakes take place respective of air or vacuum braked trailing stock.

9. Multiple unit operation enables brake equipment’s if train loco to be

controlled by those of lead locos.

10. In case of very heavy leakage in the feed pipe or failure of feed pipe

intercoupling equipment, Levin pipe brake system on trailing stock

cab be worked as single pipe system by simply isolating the feed pipe

of trailing stock from locomotive.

S.NO. DESCRIPTION PURPOSE

1 A9 - Automatic Valve Brake application for Loco as well as formations.

2 SA9 - Independent Brake Valve Brake Application for Loco alone

3 MU - 2B M.U. Operation, used as gate valve.

4 F 1 - Selector M.U. Operation, used as gate valve.

5 C2W or Additional C2 Valve Feeding B.P. Pressure to the formation.

6 24 A Double Check Valve This allow only one operation at a time.

7 C3W - Distributor Valve Proportionate Brake valve application during

A9 application.

8 C2 - Relay Valve For Locomotive Brake.

9 Pressure Switch Loco will be brought to idle during A9

emergency application.

10 D1 - Emergency Valve For Emergency brake application.

11 D1 - Pilot air valve During Dynamic brake Loco brake will be

released.

12 Pressure Limiting Valve Pilot air to C2 Relay valve for synchronized

brake application is Limited to 2.5 kg/cm2.

13 M. R. Safety Valve When M. R. Pressure goes beyond 10.5 kg /

Cm2. This valve will operate and release excess

pressure from MR.

14 Duplex Check Valve This valve will connect MR1 with feed valve

when MR (6 kg/cm2) pressure exceeds 6

kg/cm2.

15 D 24 - Feed Valve For Feed pipe Pressure 6kg/cm2.

IRAB - 1

IRAB – 1 brake system has been designed by RDSO and fitted with New

Generation ALCO locomotives. This is a complete air brake version, in which

only compressor unit is used instead of Expressor for creating air pressure

in the brake system and all the brake valves are panel mounted.

SALIENT FEATURES

1. Locomotives Brakes can be applied and released through

independent brake valve SA9, independently.

2. Formation brakes can be applied & released through Automatic

brake valve A9.

3. Locomotive brakes are applied automatically when formation brakes

are applied.

4. It is suitable for MU operation also, with which the brakes of trailing

units are controlled from leading unit.

5. Brakes in the rear loco are synchronized with lead loco brakes.

6. Emergency brake application is available to have minimum possible

braking distance, from any control stand and any loco.

7. Safety devices are incorporated to bring the engine to idle in case of

emergency brake application and train parting.

8. In case of train parting between the locos, both the locos will have

automatic brake application.

9. Automatic brake and Dynamic brakes are inter locked. So that, Auto

Brake will be released automatically when the DB is applied.

10. The system can work either with single pipe / dual pipe.

S.NO. DESCRIPTION PURPOSE

1 A9 - Automatic Valve Brake application for Loco as well as formations.

2 SA9 - Independent Brake Valve Brake Application for Loco alone

3 MU - 2B M.U. Operation, used as gate valve.

4 F 1 - Selector M.U. Operation, used as gate valve.

5 C2W or Additional C2 Valve Feeding B.P. Pressure to the formation.

6 24 A Double Check Valve This allow only one operation at a time.

7 C3W - Distributor Valve Proportionate Brake valve application during

A9 application.

8 C2 - Relay Valve For Locomotive Brake.

9 Pressure Switch Loco will be brought to idle during A9

emergency application.

10 D1 - Emergency Valve For Emergency brake application.

11 D1 - Pilot air valve During Dynamic brake Loco brake will be

released.

12 Pressure Limiting Valve Pilot air to C2 Relay valve for synchronized

brake application is Limited to 2.5 kg/cm2.

13 M. R. Safety Valve When M. R. Pressure goes beyond 10.5 kg /

Cm2. This valve will operate and release excess

pressure from MR.

14 Duplex Check Valve This valve will connect MR1 with feed valve

when MR (6 kg/cm2) pressure exceeds 6

kg/cm2.

15 D 24 - Feed Valve For Feed pipe Pressure 6kg/cm2.

LAYOUT

PEV

ARCRDV

DC

BC BC

DC

PEASD PEASD

FP

BP

GEBV

Pressure

gauge

Cut off

angle cock

Passenger alarm

system

Guard

emergencybrake

system

Corebrake

system

The distributor valve connects brake cylinder to atmosphere. The brake cylinder pressure can be raised or lowered in steps.

In case of application by alarm chain pulling, the passenger emergency alarm signal device (PEASD) is operated which in turn actuates passenger valve (PEV) causing exhaust of BP pressure through a choke of 4 mm. Opening of guard emergency brake valve also makes emergency brake application.

There are two case of braking, when only loco move and when entire train move. Consequently there are two valves in the driver cabin via SA-9 & A-9. Braking operation of above case is shown in chart below.

TYPES OF VALVES

A-9 Valve

The A-9 Automatic Brake Valve is a compact self-lapping, pressure

maintaining Brake Valve which is capable of

graduating the application or release of locomotive

and train brakes. A-9 Automatic Brake Valve has five

positions: Release, minimum Reduction, Full Service,

Over Reduction and Emergency.

SA-9 Valve

SA-9 Independent Brake Valve is a compact self-lapping, pressure

maintaining Brake Valve which is capable of graduating the application or

release of Locomotive Air Brakes independent

of Automatic Brake. The SA-9 Independent

Brake Valve is also capable of releasing an

automatic brake application on the

Locomotive without affecting the train brake

application. The SA-9 Brake Valve has three

positions: quick release, release and application.

VA-1 Release Valve

The VA-1 Release Valve without choke is used as a

remote controlled cut out cock. It is installed in the

Vacuum Brake pipe line between the VA-1B

Control Valve and the Train Vacuum Brake pipe.

HB-5 relay Air Valve

The HB-5 relay Air Valve is a pneumatic, double

piloted, three way valve that changes the air

passages through it when air pressure of a

predetermined amount or more is in the control

chamber.

HS-4 Control Air Valve

The HS-4 Control Air Valve delivers a

regulated, uniform, predetermined air

pressure, which usually serves to regulate the

operation of another device in the brake

System.

F-1 Selector Valve

The F-1 Selector Valve performs the function

of commanding the brake equipment on the

locomotive to lead or trail position of the

adjacent locomotive and ensures operation

of brakes in the trail locomotives when

initiated from the lead locomotive.

A-1 Differential Pilot Air Valve

The A-1 Differential Pilot Air Valve is designed to

activate a number of pneumatic devices for a

predetermined length of time even though its control

air supply is maintained for a considerably long period.

C2W Relay Air Valve

The C2W Relay Air Valve is a diaphragm

cooperated self-lapping valve having higher

capacity which is used as a remote controlled

pneumatic device to relay a large quantity of

main air reservoir pressure to the operating

system for brake application

MU 2B VALVE

The MU-2B Valve is a manually operated, two

positions and multiple operated valve arranged

with a pipe bracket and is normally used for

locomotive brake equipment for multiple unit

service between locomotives equipped with

similar system in conjunction with F-1 Selector Valve.

VA-1B Control Valve

The VA-1B Control Valve proportions the

amount of vacuum in the vacuum brake pipe

to the air pressure in the compressed air brake

pipe on the locomotive and acts as a pilot valve

to operate the train vacuum brake, thus

securing an application simultaneously with,

and in proportion to the locomotive air brake application.

Emergency Brake Valve

The D-1 Emergency Brake Valve is a manually

operated device which provides a means of

initiating an emergency brake application.

J-1 Safety Valve

The J-1 Safety Valve installed vertically in the

main reservoir system vents pressure at a

predetermined setting to atmosphere in

order to prevent excessive main reservoir

pressure build-up.

D-1 Automatic Drain Valve

The D-1 Automatic Drain Valve automatically

discharges precipitated moisture from reservoir

with each operating cycle of the control device.

The drain valve may be installed on main

reservoir with a sump.

D-24 B Feed Valve

The D-24 B Feed Valve is a large capacity

highly sensitive relay valve which is designed

to direct the flow of air under pressure to

various devices in air brake equipment

arrangement at a predetermined pressure.

Duplex Check Valve

Piston type duplex check valves are generally

used in Railway Compressed Air Brake systems

to prevent excessive use of auxiliary equipment

from depleting the main compressed air supply

to the detriment of the brake equipment

24-A Double Check valve

The 24-A Double Check Valve is used to permit a device to be controlled by

either of two other devices.

EXPRESSOR

The compressed air or vacuum needed for a device called expressor

mounted on engine extension shaft produces braking.

Expressor=exhauster + compressor

The expressor contains 6 cylinders, 3 of which produced compressed air

and3 of them are used for creating vacuum. These are 2 low-pressure

cylinders and one high-pressure cylinder. The low-pressure cylinder

produces air at 3.5 Kg/cm2. This air is transferred to left hand side main

reservoir.

It creates vacuum and 140 PSI air pressure in the reservoir for operating the

brake system and use in the control system etc.

The expressor is located at the free end of the engine block and driven

through the extension shaft attached to the engine crank shaft. The two are

coupled together by fast coupling (Kopper's coupling). Naturally the

expressor crank shaft has eight speeds like the engine crank shaft. There are

two types of expressor are, 6CD, 4UC & 6CD, 3UC. In 6CD, 4UC expressor

there are six cylinder and four exhauster whereas 6CD, 3UC contain six

cylinder and three exhauster.

WORKING OF COMPRESSOR

The compressor is a two stage compressor with one low pressure cylinder

and one high pressure cylinder. During the first stage of compression it

is done in the low pressure cylinder where suction is through a wire

mesh filter. After compression in the LP cylinder air is delivered into the

discharge manifold at a pressure of 30 / 35 PSI. Working of the inlet and

exhaust valves are similar to that of exhauster which automatically open or

close under differential air pressure. For inter-cooling air is then passed

through a radiator known as Inter-cooler. This is an air to air cooler where

compressed air passes through the element tubes and cool atmospheric air

is blown on the outside fins by a fan fitted on the expressor crank shaft.

Cooling of air at this stage increases the volumetric efficiency of air before it

enters the high- pressure cylinder. A safety valve known as inter cooler

safety valve set at 60 PSI is provided after the inter cooler as a protection

against high pressure developing in the after cooler due to defect of valves.

After the first stage of compression and after-cooling the air is again

compressed in a cylinder of smaller diameter to increase the pressure to 135-

140 PSI in the same way. This is the second stage of compression in the HP

cylinder. Air again needs cooling before it is finally sent to the air reservoir

and this is done while the air passes through a set of coiled tubes below the

loco superstructure.

WORKING OF EXHAUSTER

Air from vacuum train pipe is drawn into the exhauster cylinders through

the open inlet valves in the cylinder heads during its suction stroke. Each of

the exhauster cylinders has one or two inlet valves and two discharge valves

in the cylinder head.

The pressure differential between the available pressure in the vacuum train

pipe and inside the exhauster cylinder opens the inlet valve and air is drawn

into the cylinder from train pipe during suction stroke. In the next stroke of

the piston the air is compressed and forced out through the discharge valve

while the inlet valve remains closed. The differential air pressure also

automatically open or close the discharge valves, the same way as the inlet

valves operate. This process of suction of air from the train pipe continues

to create required amount of vacuum and discharge the same air to

atmosphere. The VA-1 control valve helps in maintaining the vacuum to

requisite level despite continued working of the exhauster.

OVERHAULING

The overhaul of all air brake equipment shall be carried out in accordance

with the manufacturer’s instructions or instructions/amendments.

All workshops shall keep traceable records of all overhauled and retested

equipment.

GENERAL PROCEDURES

Before a component is dismantled all external surfaces shall be

cleaned to remove accumulated dust and dirt. This can most

effectively be carried out by means of a stiff bristled brush and a

shallow bath of an approved cleaning fluid.

All cleaning and re-lubricating of valve portion parts shall be done at

a suitable bench in a clean, well lit location.

Care shall be taken to avoid mutilation or damage of pistons, springs,

rubber parts, slide valves, graduating valves etc.

Valve bodies made from hard anodised aluminium shall only be held

in a soft jawed vice. The use of holding fixtures is highly recommended

to protect sealing faces from damage or distortion.

Rubber components should be wiped with a soft cloth. The exterior of

the body shall be thoroughly cleaned.

When dismantling components, work through the component in

accordance with the sequence of operation.

Under no circumstances excessive force should be used, either in

putting the components in position or in tightening up screwed nuts

and cap screws as this can cause distortion of covers and gaskets.

Before inserting screwed components smear a light amount of grease

on the threaded part.

When fitting pressure plates or retaining rings, etc., ensure that the

smooth side having radiused edges is placed in contact with the

rubber diaphragm to avoid chaffing and damage.

All self-locking nuts shall be renewed at overhaul.

DISMANTLING FROM COACH

Before dismantling the distributor from the coach for overhauling, ensure

that the compressed air in the system is drained completely by pulling the

operating lever and holding it in position till all the air pressure is fully

exhausted.

Since the draining of air supply from the vehicle would release the brakes

fully, care should be taken to protect the vehicle and prevent its accidental

movement by suitable means.

DISMANTLING THE DISTRIBUTOR VALVE

Mount the Distributor Valve on to the Fixture with the bottom side up.

The following sequence of operation as given below for dismantling

should be adopted.

MAIN VALVE

Unscrew the 6 Nos. of Screws

(61) & carefully pull upwards the

Lower Cover Assembly (2). Take

out the Ring (23), the Diaphragm

Follower (22) and the Small

Piston of Lower Diaphragm (10)

along with its Diaphragm (6), the

Large Piston of Lower

Diaphragm (8), and the five ‘O’

Rings (32).

Press a jet of compressed air into

the bore of the Hollow Stem (30)

taking care to hold the Hollow

Stem (30) the moment it ejects

out under pressure. After

removing the hollow stem (30),

unscrew the release choke from

the top opening of the hollow

stem.

Remove the Diaphragm Holder (3) and pull out the Hollow Stem from

Diaphragm Holder.

Take out the Diaphragm Clamp (28) with its Diaphragm (27).

Unscrew the Plug (31) using the appropriate socket wrench.

Turn the Distributor Valve by 180° on the bracket and ensure that it is again

locked in the new position (bottom side down).

Unscrew the Cap (38) [with O’ Ring (99) provided in the latest version] and

take out the spring (39) and Check Valve (37) with the ‘O’ Ring (36).

Carefully remove the Diaphragm (6) from the small Piston of Lower

Diaphragm (10) and Diaphragm (27) from the Diaphragm Clamp (28). Also

remove the O Rings (4) and (5) from the Diaphragm Holder (3). Similarly

remove the ‘O’ Ring (36) from the Check Valve (37).

Using a blunt tool, remove the two Lip Seals (24) from the Diaphragm Holder

(3) and from the Lower Cover (2). Similarly, remove the ‘O’ Ring (9), ‘O’ Ring

(29) and the ‘O’ Ring (32) from the small Piston of Lower Diaphragm (10),

Diaphragm Clamp (28) and the Plug (31) respectively.

DOUBLE RELEASE VALVE

The Locking Rod (233) would have already come out when the Lower Cover

(2) is pulled out. If not, remove it from the hole.

Keep the flange face down on a soft surface like a rubber pad and press the

Operating Lever (13) hard by hand and using the appropriate circlip plier,

remove the circlip (17). Remove the Lower Seat (16) and take over the

Operating Lever. Take out the Spring Seats and Valve Operator (14) and the

spring (12).

Slowly unscrew the two Cap Screws (21) on either side and take out the two

springs (19). Take out the Sealing Rings (20) and pull out the Valves (11) and

(18).

Unscrew the Exhaust Protector (92) carefully and unscrew the Release Choke

(55) from the Exhaust Protector (92) and take out the Exhaust Ring Protector

(93).

CUT-OFF VALVE

Unscrew the bigger Cap (84) by using the appropriate socket wrench.

Alternatively, a rod of suitable diameter that can go into the side hole on the

cap can also be used.

Carefully lift off the Cap (84)

and remove the spring (85), the

Guide (86) and the Seal (83). If

the Seal does not come out

alone with the Guide and

remain in stuck in position, use

a bent tool and carefully lift it

up. Rotating the tool all around,

lift the seal uniformly and

gradually from underneath.

Ensure that the tool has no

sharp edges.

Remove the ‘O’ rings (81) from

the Guide (86) taking proper

care.

Unscrew the Diaphragm

Clamping Screw (82) using the

appropriate socket wrench. Take out the Push Rod (79).

Holding the stem part of Guide (76), pull it out carefully so that the

Diaphragm Clamp (78) also comes out. The Guide (76) is a subassembly

consisting of Seat (72) which is screwed into the Guide (76) Valve (75), spring

(73) & the Diaphragm (77).

Take out Valve (75) and the spring (73).

Pull out Diaphragm (77).

Plug is a sub-assembly consisting of an Internal Circlip (62), Spring Seats

(63), (69) and (70), spring (64) (65) and (67), a Solex Jet (66) and Valve

Finished (68) and (71). Using a suitable circlip plier, remove the Circlip (62).

Take out the Spring Seat (63) exercising caution in avoiding falling of loose

components. Take out the springs (64) (65) and (67). By pulling at Solex Jet

(66), remove the Spring Seats (69) and (70).

Take out the Valve Finished (68) and (71). Unscrew the Solex Jet from the

Valve (68).

QUICK SERVICE VALVE

With Clamp bracket in the

same position as for Cut-Off

Valve, unscrew the four

Screws (41).

Take the Cover Assembly

(40) out, taking care to pull it

up vertically.

Remove the ‘O’ Ring (32) and

‘O’ Ring (9) on the top

surface of the Body.

Slowly pull out the Glide

Plunger (219) sub-assembly

consisting of parts (52), (213),

(214), (215), (217) and (219) by

pulling at the Guide Plunger

top.

Remove the spring (216).

Remove the Diaphragm (214) from the Piston (215) of the sub-assembly.

Holding the sub-assembly in hand, unscrew the Nut (217), remove the

Washer (52) and pull out the Piston (215).

Remove the “O” Ring (213) without twisting it. Using the special tool SCT

6092 unscrew the Seat Holder (206).

Remove the “O” Rings (211) and (205).

Take out the Seat Holder Assembly (206) and using the appropriate circlip

plier, remove the Internal Circlip (17). Pull out the Seal Holder (212) using the

special tool SCT 6093). Remove the “O” Ring (210).

Using a blunt tool, carefully pull out the seal (218) from the Seal Holder (212).

Remove the Washer (209). Carefully pull out the Seal (208) by using a bent

tool and dragging up uniformly all round. Do not use any sharp hook to do

this work.

Take out the Spring Seat (207).

Using the appropriate internal circlip plier, extract the Circlip (201) at the

bottom of Seat Holder (206), taking care to prevent loose parts from inside

falling off.

Remove the Spring Seat (202), spring (203) and Valve Finished (204).

Using the same tool as was used for pulling out the Seal (218) from the Seal

Holder (212), pull out the second Seal (218) from the Cover Assembly (40).

Take out the Bush (60) carefully by pressing a jet of compressed against the

vent of quick service and the Valve Finished (59) from the hole in the top

face of Body (1).

Extract the Seal (58) and the Sealing Ring (57) by carefully pressing on the

Seal (58) on an edge to tilt it on Washer (57). Use only a blunt tool.

AUXILIARY RESERVOIR VALVE

With Body (1) in the normal position, unscrew the Cap (44) & O Ring slowly

& take out the Check Valve Spring (42) & Check Valve (43).

PRESSURE LIMITING FEATURE

Open the Cap (701) remove Circlip (702), Stem Adjusting Screw (704) using

special tool and remove Spring Seat (703) from Clamping Flange (708).

Unscrew Clamping Flange and remove spring (712) extract Diaphragm

Clamp (228) and pull out Guide (711). Remove Diaphragm (77) from Guide

(711). Remove O Ring (226) from its seating position on Cup (710) and

remove the cup. Unscrew Plug (224) and remove Valve Finished (223) and

extract the spring (709).

BRAKE BINDING

Brake binding is defined as the situation when the brake block is in contact

with the wheel tread though the A-9 valve position is in released position.

The severity of the brake binding depends on the force exerted by the brake

blocks on the wheel tread. Repercussions of brake binding in operation are

as under:-

1. Detention to trains causing loss of punctuality of trains.

2. Flat places on tire of wheel leading to bearing failure, weld failure/rail

fracture etc.

3. As a preventive measure, detachment of coach/wagon enroute

causing inconvenience to the passengers during their journey.

4. Ineffective percentage of coaching stock increases and thus,

maintenance cost is also increasing.

5. More Tractive force needed by locomotive to haul even light load train

EFFECTS

It damages the wheels

It damages the bearings

It gives discomfort to the passengers

It leads to detention to the trains

It leads to detachment of rolling stock enroute

It leads to train parting

It leads to High power / fuel consumption

It also damages the track.

CAUSES

1. Brake power creations system (Pneumatic system)

Any failure in the following parts between loco and the brake

cylinders results in brake binding

Defects in MU Washer

Defective Palm Ends

Defective Air Hoses

·Leakage through Cut- off Angle Cock

Leakage through Brake pipe

Leakage through Dirt Collector

Leakage through DV joints

Leakage through AR

Leakage through Brake cylinders

Leakage through PEAS

Leakage through GEV

Brake binding also occur due to overcharging of CR. Due to difference

in calibration of brake pipe pressure gauges in the locomotives, there

is a chance of overcharging/under charging of BP pressure during loco

changing, even though pressure gauge indicates 5.0 Kg/Cm2

Whenever the locos are reversed at the junction stations. Sometimes

it becomes difficult to charge 5.0 Kg/Cm2 pressure in rear most vehicle.

This difference of the pressures causes brake binding in the rear

portion of the train.

2. Brake power transmission system: (Brake rigging)

Brake cylinder defective.

Improper alignment of Brake Cylinder.

Uneven thickness of brake block on the same truss beam.

Hand brake fully or partially on.

Brake block mounting over the wheel.

Brake shoe jamming.

Brake beam rigid.

Improper manual adjustment of brake gear.

Fitment of wrong type of brake block (L-type instead of K-type

and vice versa).

3. Human Failure/Negligence

Non releasing of the DV manually during engine

changing/reversal.

Misunderstanding of Brake block release as CR charged during

Engine change/reversal.

4. Miscellaneous Factors

Dust/Dirt & Moisture in the Air supplied.

Mixing of different Stocks.

Non-calibration of Pressure gauges.

MEASURES

PANEL MOUNTING

A Brake Panel with an Aluminium Slab manifold accommodates the Critical

Valves of the brake system. This provision protects the Valves from the

vulnerability of impact damages from ballast / flying debris during train

operations, eliminate substantial piping work and facilitate maintenance by

unit replacement. It also contains test points for checking the pressures of

BP, AR, DV, BC and CR outputs at one location itself.

The tri plate panel mounted brake system is mainly made of aluminium alloy

plates specially machined and then sandwiched. These are used for compact

assembly of brake valves thus saving space as well as reduction of large

number of pneumatic fittings. This is modular in concept as well as

maintenance friendly Vacuum Console Panel is a compact unit, housing the

vacuum valves as well as the filter sand also a small panel comprising of all

other associated valves related to vacuum brake system in locomotive. This

eliminates dispersed fitment of vacuum valves in locomotive brake system

thus eliminating leakages as well as saving of space in the locomotive.

The Brake Panel

Module for LHB

Coach serves to

group together

with interconnect

ions in one’s ingle

assembly all Valves,

Cut Out Cock, Drain

Cock, Pressure

Switch housed in a

Braking Panel with

Reservoirs, Choke

Filters, etc., of the brake equipment within the space marked as A0 of the

brake schematic. Other equipment in the schematic are allocated in special

places of the Coach braking layout. It facilitates easy removal for overhaul

and unit replacement.

Construction

The Brake Panel Module is a fabricated stainless steel frame and contains a

Aluminium Manifold to which component / subassemblies are attached. The

list of items forming part of their location is included in the parts list of Brake

Container drawing along with the piping circuit details.

Benefits of Panel Mounted Air Brake

It provides compact city to the system thus reducing space utilized by

the braking system on the locomotives.

It reduces large number of pneumatic fittings.

This is maintenance friendly for the technician.

It also reduces leakage as it does not require any compactness for the

fitting of vacuum and pneumatic valves.

By using this, it becomes very easy to identify the trouble in running

condition.

It is very reliable and works satisfactorily.

DEVELOPMENT IN OTHER COUNTRIES

AWS

The automatic warning system (AWS) is a form of limited cab signalling and

train protection system introduced in 1956 in the United Kingdom to help

train drivers observe and obey signals.

PRINCIPLE

AWS is part of the signalling system

and warns the driver about the

aspect of the next signal. These

warnings are normally given 200

yards (180 metres) before the signal.

Information about the signal aspect

is conveyed electromagnetically to

the moving train through equipment

fixed in the middle of the track,

known as AWS inductors. Each

inductor contains a permanent magnet and an electromagnet which

'cancels' the effect of the permanent magnet. The system is fail-safe because

the electromagnet is required to be energised to give the 'clear' indication,

the 'warning' indication being given by the permanent magnet alone.

The system basically consists of a relay control box, electro-pneumatic (EP)

valves connected to the braking system, a 'sunflower' indicator mounted in

a prominent position in the driver's cab, a magnetically operated 'receiver'

underneath the locomotive/multiple unit driving car, a driver's reset plunger

and a static voltage-converter providing operating voltages of 12 V and 40

V from the unit supply, plus an isolating handle that is both an electrical and

vacuum pipe/air isolator.

When the AWS inductor is reached, the AWS sets a visual indicator in the

driver's cab and gives an audible indication. If the signal being approached

is displaying a 'clear' aspect, the AWS will sound a bell (modern

locomotives/multiple unit’s use an electronic device that gives a distinctive

'ping' that can be heard in Pacers and some of the more recent DMU/EMU

stock) and leave the visual indicator black. This lets the driver know that the

next signal is showing 'clear' and that the AWS system is working. If the

signal being approached is displaying a restrictive aspect (red, yellow or

double yellow in colour-light installations or a distant semaphore at caution

(horizontal) in mechanically signalled installations), the AWS will sound a

horn continuously until the driver pushes and releases a button to

acknowledge it. The AWS will also give a warning horn on the approach to

certain permanent speed restrictions and all temporary and emergency

speed restrictions. When the warning is acknowledged, the horn stops and

the visual indicator changes to a pattern of black and yellow spokes, which

persists until the next AWS inductor and reminds the driver that they have

cancelled the AWS and therefore have full responsibility for controlling the

train. If the button is not pressed and released within 3–4 seconds, a full

brake application brings the train to a halt. The system has a fail-safe

mechanism built in if the driver collapses onto the AWS cancel button

whereby it is not the press of the button that cancels the warning, it is when

the driver lets go after the downward motion.

COUNTRIES

Northern Ireland

Hong Kong, MTR East Rail Line (only used by intercity through trains;

local trains use TBL as of 2012, enhanced with ATP)

Queensland, Australia; sometimes enhanced with ATP.

Adelaide, South Australia

CAWS

The Continuous Automatic Warning System (CAWS) is a form of cab

signalling and train protection system used in Ireland to help train drivers

observe and obey lineside signals.

PRINCIPLE

CAWS repeats the aspects

shown by the lineside colour

light signals on an aspect

display unit (ADU) inside the

driver's cab. The ADU

continuously displays the

aspect that was shown by the

previous signal until updated

about 350 metres before the

next signal. The ADU then

displays the aspect shown by

that signal.

A change of ADU display to a less restrictive aspect (e.g., double yellow to

green) is termed an upgrade, while a change to a more restrictive aspect

(e.g., single yellow to red) is called a downgrade. Any change of ADU display

is accompanied by an audible indication. A momentary audible ‘warble’

sound indicates an upgrade. A downgrade is accompanied by a continuous

audible tone and the illumination of the Acknowledge Switch that must be

pressed by the driver within 7-seconds to prevent an automatic brake

application occurring for one minute. This is not recoverable until the time

has expired. Acknowledgement by the driver within the first 7-seconds

immediately silences the tone.

BIBLIOGRAPHY

I.R.I.M.E.E, JAMALPUR

R.D.S.O, LUCKNOW

TKD SHED LIBRARY

www.irfca.org

www.railway-technical.com

Handbook on Maintenance of Air Brake System in LHB Coaches (FTIL

Type)

Pocket book on Air Brake System for Drivers and Guards on freight

stock

Handbook on Bogie Mounted Brake System of ICF Coaches

Trouble Shooting Guide on Brake Binding in Coaching Stock.