RAILS

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Railway track
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Rail section
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Rails

• It can be considered as steel girders for the
  purpose of carrying axle load. They are made on
  high carbon steel to withstand the wear and tear.
  Flat footed rails are most commonly used in
  railway track.

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Functions

• It provide hard, smooth and unchanging surface
  for passage of heavy steel
• It bear the stresses developed due to heavy
  vertical loads, lateral and breaking forces and
  thermal stresses
• It transmit the loads to sleepers and
  consequently reduce pressure on ballast and
  formation below

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Composition of rail steel

• For ordinary rails

Carbon (C) 0.55-0.68
Manganese (Mn) 0.65-0.905
Silicon (Si) 0.05-0.3
Sulphur (S) 0.05 or below
Phosphorus (P 0.06 or below
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• For rails on points and crossing

Carbon (C) 0.5-0.6
Manganese (Mn) 0.95-1.25
Silicon (Si) 0.05-0.20
Sulphur (S) 0.06 or below
Phosphorus (P 0.06 or below
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Requirements

• They should be proper composition of steel
• The vertical stiffness to be high enough to
  transmit to several sleeper underneath
• The head of rail must be sufficiently deep to
  allow for an adequate margin of vertical wear
• The wearing surface to be hard

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• Foot of rail should be wide enough so that the
  rails are stable against overturning especially
  on curves
• The fillet radius must be large to reduce
  concentration of stresses
• The tensile strength of rail should not less
  than 72kg/m2

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Types of rail sections

• Double headed rails (D.H)
• Bull headed rails (B.H)
• Flat-footed rails (F.F)

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Standard rail sections gauge wise
Gauge Rail sec Type of sec Rail length Rail sec (kg/m)
B.G 60 kg/m 52 kg/m 60 MR 52 MR (IRS) 13m (39ft old) 60 MR 52 MR 45 MR
M.G 90 Ibs/yd 75 Ibs/yd 60 lbs/yd 90 R(RBS) 75 R(RBS) 60 R(RBS) 12m (39ft old) 45 MR 37 MR 30 MR
N.G 50 lbs/yd 50 R(RBS) 12m (39 ft old) 25 MR
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Specifications
s.no specifications 90R 52kg/m 60kg/m
1 Traffic density Upto 10 GMT 20-30 GMT 35 GMT
2 Speed Upto 100km/h Upto 130km/h Upto 160km/h
3 Axle load M.L standard Upto M.L standard Upto M.L standard
4 Service life 20-25yrs 20-25yrs 20-25yrs
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DETAILS OF STANDARD RAIL SECS USED IN INDIAL
RAILWAYS
S.no Type of rail sec Wt/metre (kg) Area (sq mm) Dims of rail sections (mm) Dims of rail sections (mm) Dims of rail sections (mm) Dims of rail sections (mm) Dims of rail sections (mm) Dims of rail sections (mm)
S.no Type of rail sec Wt/metre (kg) Area (sq mm) A B C D E F
1 50R 24.8 3168 104.8 100 52.4 9.9 32.9 15.1
2 60R 29.76 3800 114.8 109.5 57.2 11.1 35.7 16.7
3 75R 37.13 4737 128.6 122.2 61.9 13.1 39.7 18.7
4 90R 44.61 5795 142.9 136.5 66.7 43.7 43.7 20.6
5 52kg 51.89 6615 156 136 67 51 51 29
6 60kg 60.34 7638 172 150 74.3 51 51 31.5
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Flat footed rails

• Limitations
• They have more strength and stiffness, both
  vertically and laterally, than B.H rails
• Fittings of rails with sleeper is similar, so
  they can be easily laid and re-laid
• No chairs and keys are required as in case of B.H
  rails
• The straightening of bent rails, replacing of
  rails and dehogging of battered rails are
  difficult
• The fittings get more loosened frequently than in
  case of B.H
• Difficult to maintain the points and crossings

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Bull headed rails

• Limitations
• They keep better alignment and give more solid
  and smoother tracks
• Long life and easier for manufacture
• Rails are disconnected from sleepers as they have
  no direct connection with the later
• Rails can be removed and replaced easily
• Require additional cost of iron chairs
• Less strength and stiffness
• Costly fittings
• Require heavy maintenance cost

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Selection of rails

• The rail is designated by its weight per unit
  length
• Factors
• Speed of train
• The gauge of the track
• The axle load and nature of traffic
• Types of rails
• Spacing of rails
• Max permissible wear on the top of rails

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Length of rails

• Factors
• The length of rails is so chosen that the
  manufacturing cost is most reasonable
• It depend upon transportation facilities
• To some extent, the length is also limited by the
  lifting and handling, during the loading and
  unloading of wagons
• On Indian railways standard lengths
• l 12.8m(42 sq ft) for B.G say 13m
• l 11.89m(39 sq ft) for M.G say 12m

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Rail Corrugations

• Due to effective layout or defective maintenance
  sudden application of brakes, wavery surface
  develops at the head of rails resulting in the
  rails surface getting corrugated
• Passage of train over such surface results in
  roaring sound. Such rails are known as roaring of
  rails

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Rail joints

• It is necessary to hold together the adjoining
  ends of the rails in the correct position, both
  the horizontal and vertical plane
• Requirements
• Ends to remain true
• Should and stiff
• Provide for expansion
• Perfectly elastic(laterally and vertically)
• End should not be battered
• Provide facility for removal and replacement
• Economical in cost

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• Types
• Supported joints
• Suspended joint
• Bridge rail joint
• Welded rail joint
• Square or eve rail joint