WEAR OF RAILS

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WEAR OF RAILS
Engr. Muhammad Hussain
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TYPES

1. Wear on head of rail
2. Wear on ends of rail
3. Wear of rail on curve

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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.

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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.

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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.

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CONT

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

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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 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
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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 120
Flange of Wheel
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TYPES OF CROSSING
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TYPES OF CROSSING

1. Square Crossing
2. Diamond Crossing
3. Cross Over
4. Scissor Crossing
5. Symmetrical Split

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SQUARE CROSSING

• When two railway lines cross each other at 90o it
  is called Square Crossing

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DIAMOND CROSSING

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

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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

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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.

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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.

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CREEP OF RAILS
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CREEP OF RAILS

• Definition
• It is a horizontal movement of rails in a track.
  It can be minimized but cannot be stopped.

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Causes Of Creep

• There are three main causes of Creep
• Wave motion of trains.
• Expansion and contraction of rails due to
  variation in temperature.
• Due to starting, accelerating, slowing down
  (decelerating) and stopping of trains.

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Wave Motion

• 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

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Direction Of Creep

• Alignment Of Track
• Creep is more on curve track than on a tangent
  portion (straight track).
• Grades
• In upgrades tracks, creep will be less and in
  down grades track creep will be more.
• Direction of movement of trains
• Creep will be more in the direction to which the
  loaded train moves more.

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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.

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Result Of Creep

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

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Square Position of Sleeper
Sleeper out of square
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SOME IMPORTANT TERMS
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SUPER ELEVATION

• The outer edge is raised with respect to the
  inner edge on curve rail section called super
  elevation.
• SUPER ELEVATION
• Where,
• G Gauge of track (ft)
• V Design speed of train (ft/Sec)
• R Radius of curvature (ft)
• g Acceleration due to gravity (ft/sec2)

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Problem

• Fine the Design speed of railroad on a curve if
  Super elevation is 0.5ft, Gauge is 5-6 and
  Radius of Curve is 3500 ft
• Sol
• 101 Km/h

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THANKS