Special Rail Sections

Special Rail Sections

• Girder Rail
• Gird Rail
• Grooved Rail
• Crane Rails (175lbs, 135lbs, 105lbs)

History of Rails

History of Rails

1767: Cast Iron Plate (5ft Long).

1776-1793: Cast Iron Rail (3ft Long).

1789: Cast Iron Edge Rail (Fish Bellied Plate).

1797: Cast Iron Edge Rail.

1802: Cast Iron Rail (4-1/2ft Long).

1808: Cast Iron Rail.

1808-1811: Malleable Iron Rail.

1816: Cast Iron Edge Rail.

1820: Brikenshaw Rolled Iron Rail (26lbs).

1830: Clarence Rolled Iron Rail (33lb).

1831: R. L. Stevens T-Rail.

1831: P. R. R. Amboy Div. (41lbs).

1835: U or Bridge Rail (40lbs).

1837: Lock Rail (58lbs).

1844: Bullhead Rail.

1844: Evans U Rail (40lbs).

1845: First U.S. T-Rail.

1858: Hollow Iron Rail.

1858: P. R. R. Std. (85lbs).

1864: P. R. R. Std. (67lbs).

1866: First Bessemer Rail Rolled in U.S. (50lbs).

1876: 60lbs.

1900: 100lbs.

1916: 130lbs.

1930: 131lbs.

1947: 155lbs.

 

Tests Prescribed for Rails

The following tests are prescribed for acceptance of the rails:

1. Tests for Grade 710 rails:
• Falling Weight Test.
• Chemical Analysis Test.
• Tensile Test.
2. Tests for Grade 880 rails:
• Falling Weight Test.
• Chemical Analysis Test.
• Tensile Test.
• Microscopic Examination from Top End/Bottom and Crop.
• Hardness Test for 10% of the Cests.
• Hydrogen Content in Liquid Steel to be Checked for 5% of Costs and shall be Less than 3 PPM.

Wieght of Rail vs Axle Load

Though the weight of the rail and its section depends upon various consideration, yet the heaviest axle load which the rail has to carry plays the most important role. The following is the thumb rule for giving the maximum axle load with relation to rail section:

• Maximum Axle Load = 560 X sectional weight of rail in lbs per yard or Kg per metre.
• Max. Axle load for 90lbs rail = 560 X 90 = 50400lbs = 22.50 Tons
• Max. Axle load for 52Kg rail = 560 X 52 = 29.12 MT.

Requirements for an Ideal Rail Section

1. The section of the rail should be such that the load of each wheels is transferred to the sleepers without exceeding the permissible stresses.
2. The section of the rail should be able to withstand the lateral forces caused due to fast moving trains.
3. The underside of the head and top of the foot of the rail section should be of such aslope that the fishplates fit snugly.
4. The center of gravity of the rail section should preferably coincide the center of the height of the rail so that maximum tensile and compressive stresses are nearly equal.
5. The web of the rail section should be such that it can safely bear the vertical load without buckling.
6. The head of the rail should be sufficiently thick for adequate margin of vertical wear.
7. The foot of rail should provide sufficient bearing area on the underlying sleepers so that the compressive stresses on the timber sleeper remain within permissible limits.
8. The section of the rails should be such that the ends of two adjacent rails can be efficiently jointed with a pair of fish plates.
9. The surfaces for rail table and gauge face should be sufficiently hard to resist the wear.
10. The contact area between the rail and wheel flange should be as large as possible to reduce the contact stresses.
11. The specimen of rail should be able to withstand the blow of a falling weight in the test specified by the specifications.
12. The composition of the steel should conform to the specifications adopted for its manufacture by Open Hearth of Duplex Process.
13. The overall height of the rail should be adequate to provide sufficient stiffness and strength as a simply supported beam.
14. The stiffness of a rail section depends upon the moment of inertia. The economical design should provide maximum moment of inertia per unit weigh of rail with due regard to other factors.
15. The section moduli of the rail section and that of a pair of fish plates should be adequate so as to keep the rail and fish plates within permissible limits.
16. The foot of the rail should be wide enough so that the rail is stable against overturning.

Functions of the Rails

The main functions of rails in a railway track are as under:

• Rails provide a continuous and level surface for the movement of the trains with minimum friction with steel wheels of the rolling stock.
• Rails provide strength, durability and lateral guidance to the track.
• Rails transmit the axle load to sleepers, which transfer the same load to the underlying ballast and formation.
• Rails bear the stresses developed due to heavy vertical loads, breaking forces and temperature variance.