Sleeper

Sleeper is a transverse support for a railway track to give stiffness to it. the sleeper should counteract the tendency of forces, which tends to distribute the track and should acts as elastic medium between the rail and the ballast in order to absorb all the shocks and vibrations of the trains.

 

Functions of sleepers

1. to hold the rails to correct gauge.

2. to distribute the axle load over a sufficient large area of ballast

3. to give firm  and even support to the rails.

4. to maintain the alignment and proper grade of track.

5. to provide easy replacement of rails fastening without disturbing traffic seriously.

6. to provide insulation for electrified track.

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Coning of wheel

If the distance between the inside edge of the flanges is kept equal to the gauge distance, the flange of the wheel would rub against the inside face of the rail. to prevent the distance between the inside edge of the flange is kept less than the gauge distance.

 

if the rim of the wheels rests flat on the rails, there would be lateral movement of the axle resulting in damage to inside edge of the rails. this is prevented by sloping the wheels at a slope of 1 in 20. the foot of the rail resting on the sleepers is also tilted to a slope of 1 in 20. this sloping of wheel from the vertical axis is known as CONING OF WHEELS.

 

 

one of the undesired  effects of Coning of wheels is that the pressure of the wheel is always towards the inner edge of the rail which tends to wear out quickly. to reduce this wear of the rail, the rails are also placed at an inward slope  of 1 in 20.

the cutting of the sleepers to provide tilting of the rails is known as Adzing..

Advantages:

1)  Tilting of the rails results in uniform  wear of the head of the rail.

2)  proper gauge is maintained

3)  life of sleeper and rail is increased

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Permanent way

 A permanent way is the combination of rails, sleepers, ballasts,fixtures and fastenings, etc.

This term is used to distinguish the finished and permanent track from a temporary track which is laid for temporary work, i.e. for transporting construction material etc on major construction sites.

 

such a temporary track is removed as soon as the construction completed. the purpose of use of a permanent way is to provide the permanent facility for safety and quick movement of normal  commercial  traffic between the starting and destination stations. permanent way costs nearly 40% of the total investment to the railways.

Requirements of  Ideal  permanent   way

 

The alignment of the should be correct.

The track should process sufficient elasticity. It should also possess sufficient lateral rigidity and stiffness so that it may withstand the lateral thrust and centrifugal forces.

The track should be designed that load of the train should be distribute uniformly over it.

the gauge of track should be correct and uniform.

the track should possess high resistance to damage at the time of derailment and its maintenance cost is minimum.

in straight reaches, the rail level should be same while on curves, proper super elevation should be provided.

the friction between the wheels of rolling stock and rail should be minimum

the gradient should be uniform joints, point and crossings should be designed and maintained properly.

facilities of repair, replacement etc of damage portion of track should be adequate.

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