05 Rails (Railway Engineering Lectures هندسة السكك الحديدية & Dr. Walied A. Elsaigh)
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The document summarizes key aspects of railway engineering as it relates to rails, including: - Standard rail sections used internationally and factors that influence rail selection. - Common rail tests like falling weight, tensile strength, and hammer tests. - Types of rail defects like wear, battering, hogging, and corrugation - their causes and remedial measures. - Methods to measure rail wear including weighing and laser profiling of rail sections.
![Rail Tests Falling Weight Test
[Tup Test]
A rail piece of 1.5 m (5 ft) is cut. The rail is supported between the bearers
at a prescribed distance. A tup of specified weight (see table) is dropped
from a height of 7.2 m on the centre of the test piece.
One falling weight test is done for
every cast of 100 metric tonnes.
The rail specimen should withstand
the blow without any fracture.](https://image.slidesharecdn.com/rails-200415164415/85/05-Rails-Railway-Engineering-Lectures-Dr-Walied-A-Elsaigh-11-320.jpg)
05 Rails (Railway Engineering Lectures هندسة السكك الحديدية & Dr. Walied A. Elsaigh)
- 1. Dr. Walied A. Elsaigh welsaigh@ksu.edu.sa Asst. Prof. of Civil Engineering Jumada’-I 1437H CE 435 Railway Engineering RailsFoot Web Head Flat Foot Rail
- 2. Text Book Railway Engineering, Satish and Agarwal, 2nd edition, 2013 Chapter 6 Page 81-105
- 5. Standard Rail Sections Branding and Stamping Common section codes RE: American Railway Engineering Maintenance of Way Association (AREMA). REHF: AREMA “head free” section. ARA-A: American Railway Association, “A” section. ARA-B: American Railway Association, “B” section. ASCE: American Society of Civil Engineers.
- 6. Cont. Standard Rail Sections
- 7. HT = Height BW = Width of Head HW = Width of Head W = Web (at center point) HD = Depth of Head FD = Fishing BD =Depth of Base E =Bolt Hole Elevation X-Section of Rail Cont. Standard Rail Sections
- 8. Cont. Standard Rail Sections The rail is designated by its weight per unit length. 52 kg/m rail denotes that it has a weight of 52 kg per metre length
- 9. Factors affecting choice of appropriate rail section: Heaviest axle load Maximum permissible speed Depth of ballast cushion Type and spacing of sleepers Selection of Rail Section Rule of Thumb (Relationship between maximum axle load and weight of rail section) Maximum axle load = 560 × sectional weight of rail Example #1: Determine the maximum axle load for 90 lb/yard rail section Maximum axle load = 560 × 90 lbs = 50,400 lbs or 22.5 t Example #2: Determine the suitable rail section weight (kg/ m) to carry a maximum axle load of 29 ton? (ans: 52kg/m) Sectional weight of rail in lbs per yard or kg per metre
- 10. Lack of facilities for transport of longer rails, particularly on curves. Difficulties in manufacturing very long rails. Difficulties in acquiring bigger expansion joints for long rails. Heavy internal thermal stresses in long rails. Rail Length Theoretically, the longer rails are preferred, why? Reduces number of joints less cost (construction & maintenance) Provides smooth and comfortable rides. Length of a rail is limited, Why? Find out the following: Rail section and length used in KSA
- 11. Rail Tests Falling Weight Test [Tup Test] A rail piece of 1.5 m (5 ft) is cut. The rail is supported between the bearers at a prescribed distance. A tup of specified weight (see table) is dropped from a height of 7.2 m on the centre of the test piece. One falling weight test is done for every cast of 100 metric tonnes. The rail specimen should withstand the blow without any fracture.
- 12. Rail Tests Tensile Test A test piece is taken from the head of a rail section and subjected to the tensile test. The tensile strength of the rail should not be less than 720 N/mm2, minimum elongation of 12%
- 13. Rail Tests Hammer Test No fracture should occur or a lap be disclosed, otherwise the batch is rejected. The foot of the test rail piece is rigidly gripped in a vertical position and the head of the rail is struck with a 4.5 kg hammer. Sufficient number of blows are given till the web bends and the dimensional value of A given in the Table below
- 14. Rail Defects Rail Wear Due to the passage of moving loads and friction between the rail and the wheel, the rail head gets worn out in the course of service. The impact of moving loads, Forces due to acceleration, deceleration, and braking of wheels, The abrasion due to rail–wheel interaction, Effects of weather conditions (i.e. temperature, rains, presence of sand). Why wear occurs ? (causes of rail-head wear)
- 15. Rail Defects Types of Rail Wear Where in the rail wear occurs ? on top of the rail head (vertical wear) on the sides of the rail head (lateral wear) on the ends of the rail (battering of rail ends)
- 16. Rail Defects Locations of Rail Wear Where in the track wear occurs ? on sharp curves, due to centrifugal forces on steep gradients, due to the extra force applied by the engine on approaches to railway stations, due to acceleration and deceleration in tunnels and coastal areas, due to humidity and weather effects
- 17. Rail Defects How to Reduce Rail Wear ? Better maintenance of the track to ensure good packing as well as proper alignment and use of the correct gauge Reduction in the number of joints by welding Lubricating the gauge face of the outer rail in case of curves Providing check rails in the case of sharp curves
- 18. Rail Defects By weighing the rail By profiling the rail section (Special instruments are available) incorporates the latest laser and video camera technology to provide accurate and immediate report on the profile and wear condition of the rail whilst travelling at track speeds. The video cameras capture full cross-sectional rail profiles from the base/web fillet area up to the top-of-rail surface to allow comprehensive and accurate rail measurements. http://www.mermecgroup.com/diagnostics/tr ackin%20specti-on/60/1/rail-profile.php Adapted from: How to Measure Rail Wear ?
- 19. Rail Defects Rail End Batter The hammering action of moving loads on rail joints batters the rail ends in due course of time. Batter = Beat (hit) How measured? If the batter is up to 2 mm, it is classified ‘average’, If it is between 2 and 3 mm, it is classified as ‘severe’.
- 20. Rail Defects Rail End Batter Adapted from: http://www.bitlanders.com/blogs/corrugation-wear-of-rails- failure-of-rails-and-rails-welding/441935
- 21. Rail Defects Hogging Rail Rail ends get hogged due to poor maintenance of the rail joint, yielding formation, loose and faulty fastenings. Remedial action? (1) Replace joint, (2) Welding joint, (3) Dehogging, (4) Cropping Hogged rails: Due to worn out of rail ends due to load repetition, the rail gets bent down at its ends, creating what is termed as “hogged rails”. Consequence ? Rough riding, more vibration leading to more defects. Causes? loose packing under joints and loose fish plate.
- 22. Rail Defects Corrugated Rail Corrugated or Roaring rails: The heads of rails corrugate (fine depressions on the surface of rails). Causes roaring sounds when wheels pass over it. Causes? Found at places where trains brakes or starts its journey, other reasons such as: composition of steel used to manufacture rails. Consequences? (1) Unpleasant roaring sound which cause discomfort to passengers and residents along side the rail track (2) Vibration causes further deterioration to other track elements. Remedial action? (1) Replace rail if corrugation is severe and the defect is limited to small number of rails (2) Grind top surface of rail, a grinding train moving at 3 km per hour can be used (as in Germany).