WEAR OF RAILS

TYPES Wear on head of rail Wear on ends of rail Wear of rail on curve

WEAR ON HEAD OF RAIL Wear on head of rail is due to abrasion on moving rails. Due to grinding action of sand or dust between the rails and wheels of the train.

Cont… When train starts or applies brakes, the wheel just slides on the rails causing wear on the head. Load coming on to a track may exceed the carrying capacity of the section. Thus causing the wear in the head of rail.

WEAR AT THE ENDS OF THE RAIL It is much greater than the wear on the head of the rail. This type of the wear is resulted due to the blows which the rail receive when the wheel jumps the space between the rail ends. The ends are battered by such blows. The contact surface between the sleepers and the rail is worn as the as the effect of these blows increased.

CONT… The ballast under the sleepers will loosen due to increase in the intensity of vibrations, also the sleeper will depressed due the displacement of ballast, also the fish plates will get loose under the constant impact of increasing vibrations

WEAR OF RAIL ON CURVE On the curve the wear of the rail takes place in both inner and outer rails. On the curve the, the outer wheel has to move through greater distance than the inner wheel. And the inner wheel has to slide over the inner rail. Curved Crossing

CONT… Wheel As a result of this sliding wear of the inner rail occur because the metal in the rail head is burnt. At the curve, flange of outer wheel will strike the inner surface of the outer wheel due to centrifugal force. Thus side of the head of rail wears out. Slope 1:20 Flange of Wheel

TYPES OF CROSSING

TYPES OF CROSSING Square Crossing Diamond Crossing Cross Over Scissor Crossing Symmetrical Split

SQUARE CROSSING When to railway lines cross each other at 90o it is called Square Crossing

DIAMOND CROSSING Angle of intersection (crossing angle) of two tracks is when not 900 , then crossing is called diamond crossing.

CROSS OVER A cross over is introduced to transfer a train from one track to another track which may or may not be parallel to each other

SCISSOR CROSSING If two cross overs are required between two parallel tracks and there is no sufficient space for crossing to be kept separate, then they are made to over-lap each other and result is a scissor crossing.

SYMMETRICAL SPLIT If radius of main track is equal to the radius of turn out curve, then the turn out is known as symmetrical split.

CREEP OF RAILS

CREEP OF RAILS Definition: It is a horizontal movement of rails in a track. It can be minimized but cannot be stopped.

Causes of creep The causes of creep in rail can be broadly classified into two categories 1. Major causes of creep 2. Minor causes of creep

Major causes of creep 1. Creep may be developed due to forces that come in operation when the train is starting or stopping by application of brakes. Increase of starting the wheel pushes the rail backward and hence the direction of creep is in backward direction.

When brakes are applied then wheels of the vehicles push the rails in forward direction and hence the creep is in forward direction.

2. Creep is also developed due to wave motions 2. Creep is also developed due to wave motions. When train passes on a track, the portion of rail length under the wheel of train will under more stresses and little depression will exist. As a result, this depression will cause (set) a wave motion in the rail or track

3. Another reason creep develops because of unequal expansion and contraction owing to change in temperature.

Minor causes of creep Rails not properly fixed to sleepers. Bad drainage of ballast. Bad quality of sleepers used. Improper consolidation of formation bed. Incorrect allowance for rail expansion. Rail joints maintained in bad conditions. Rails fixed too tight to carry the traffic.

Direction Of Creep Alignment Of Track: Creep is more on curve track than on a tangent portion (straight track). Direction of movement of trains: Creep will be more in the direction to which the loaded train moves more.

Extent Of Creep Creep does not vary at some constant rate. (it is not constant) Creep does not continue in one direction only. Creep for two rails of the track will not be in equal amount.

Result Of Creep Expansion gap is reduced, buckling of track take place. Sleepers are moved out of a square. Crossing points get disturbed.

Square Position of Sleeper Sleeper out of square