brake gear

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BASICALLY TWO

ASSEMBLIES

Brake Power Generation System i.e. Pneumatic System

Brake Power Transmission System i.e. Mechanical System

commonly called BRAKE GEAR.

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Brake Power Generation System i.e. PneumaticSystem ( Main component DV )

Brake Power Transmission System i.e. Mechanical

System commonly called BRAKE GEAR

Single pipeSingle pipe

Twin pipe

Underframe Mounted System ( Main component SAB

Slack Adjuster )

Bogie Mounted System ( Main component BMBC )

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Brake PowerGeneration System

i.e. Pneumatic System

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AIR BRAKE LAYOUT FOR COACHING STOCK

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Brake Power Transmission System

i.e. Mechanical System

commonly called

BRAKE GEAR

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Bogie Mounted Brake System

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1

C

9

8

107

5

6

4

3

2

b

INLET PLUGcompressed air issupplied from loco

1. Brake cylinder 2. Piston assembly arm

3. lever 4. Brake shoe with brake block

5. wheel 6. Brake beam

7. Curved pull rod

Brake Rigging ofBogie Mounted Brake System

8. lever

9. Brake shoe with brake block

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Brake Rigging of Bogie Mounted Brake System

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BOGIE MOUNTED AIRBRAKE SYSTEM

WHY?

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The Limited vendors ofSAB slack adjuster .

Vibration of the pull rod during running cause rattling noise.

The SAB slack adjuster brake pull rod is supported by spring

loaded nylon rollers which wears out very fast. Thus it becomes

inefficient unless the nylon rollers are changed regularly.

Breakage ofSAB slack adjuster pull rod also occurs due tobending while negotiating the curves.

The components like SAB slack adjuster support brackets, pins

and bushes, pull rod and support for pull rod provided on the

under frame increases additional weight of the coach.

The total brake force is in the order of 100% of the tare weight

and therefore the brake linkages are heavily loaded resulting in

frequent maintenance demands on brake beam, brake head,

brake gear pins and bushes

Limitations of underframe mounted brake system

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Item Conventional

Air BrakeSystem

Bogie

MountedBrake System

Weight reduction (as

compared to

conventional air brake system)

- 492 kg.

Braking distance at

110 kmph (18

coaches )

905 m 800 m

No. of pins and

bushes

102 84

Brake block wear

rate

More Less

COMPARISION OF IMPORTANT PARAMETERS

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Design Features of Bogie MountedBrake Cylinder

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External slack adjusters have been eliminated.

Total four nos. of 8 (203.2 mm) size brake

cylinders (two per bogie) are used in place of

two 14 (355 mm) size under frame mountedbrake cylinders in standard air brake.

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Each cylinder is provided with built-in singleacting slack adjuster to take up the clearance

automatically between wheel and brake block

whenever the clearance increases due to wear

on the brake block and the wheel.

The maximum slack take-up is 305 mm.

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These cylinders are mounted between centrallongitudinal members connecting the bogie

transom and the headstock on either side.

Each cylinder controls the braking of wheels ofeach axle. Piston stroke is 32 mm.

Provided with less number of brake fittings,

therefore, easy to maintain.

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High friction K type composite brake blocks areused, whose life is 5-6 times more than that of cast

iron brake blocks.

Unusual noise on run is completely eliminated.

Use of curved pull rod with additional hole for

manual adjustment of brake gear.

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The overall weight saving per coach is about492 kg.

Number of pins and bushes reduced from 102 to

84.

Braking distance has come down from 905 mm to

800 mm

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Working Principle of BMBC

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Working Principle of BMBC

The change has been incorporated in brake gearonly.

The system will respond to action of A-9 valve insimilar fashion as in the case of standard air brake system during brake application andrelease.

orThere is no change in the overall brake system inbogie mounted arrangement up to the action ofDV.

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Brake Application

Compressed air is admitted to brake cylinder

between piston and cylinder body forces thepiston trunk assembly to move outward against

the force of release spring.

The brake force is transmitted through the

trunion body, adjusting screw, adjusting tube,

cross head, brake rigging and finally to the brake

blocks

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Brake Release

When the compressed air from brake cylinder is

vented the release spring moves the piston trunksub-assembly to release piston.

As soon as the piston stroke exceeds (32 mm)

during return stroke the adjustment (in built-in

one way slack adjuster) takes place

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Difference between SAB& Inbuilt Slack Adjusterof BMBC

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Difference between SAB & Inbuilt Slack

Adjuster of BMBC

SAB

Take up and pay outthe clearance betweenthe wheel & brakeblock.

The effective length ofpull rod is decreasedduring take up the

clearance.

Inbuilt Slack

adjuster of BMBC

Only take up theclearance between thewheel & brake block.

The effective length ofpiston rod isincreased during take

up the clearance.

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Difference between SAB & Inbuilt SlackAdjuster of BMBC

SAB

It maintains a uniformpiston stroke through

out the formation.

It does not require

adjustment of piston

stroke every trip.

Inbuilt Slack

adjuster of BMBC

The piston stroke of thecylinder is not uniform

through out the

formation and varies up

to 60mm.

Every trip the piston

stroke require to be

adjusted.

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SAB

Spindle is made up oftriple start thread.

To adjust the slack,the length of the pullrod is increased ordecreased duringforward stroke.

Inbuilt Slack

adjuster of BMBC

Adjusting screw(spindle) is made upof double start thread.

To adjust the slack thelength of the pistonrod is increasedduring return stroke.

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SAB

When length of the pull

rod increased

manually the clearancebetween the wheel &

brake block increases.

Inbuilt Slack

adjuster of BMBC

When the effective

length of piston rod is

increased manually,the clearance between

the wheel & brake

block decreases.

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Manual Adjustment of BMBC

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Manual Adjustment

A red paint mark on the adjusting tube sub-

assembly indicates that the piston unit has

extended over its full range and requires re-

setting.

The design of the brake-rigging unit is done in

such a way that range of slack adjuster covers

the life of brake blocks so that re-setting and

replacing brake blocks will be done at the sametime.

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brake gear

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