Shri.ppt
- 1. MANAKULA VINAYAGAR INSTITUTE OF TECHNOLOGY KALITHEERTHALKUPPAM,PUDUCHERRY DEPARTMENT OF MECHANICAL ENGINEERING A SEMINAR ON DESIGN OF RAILS SECTIONS AND ITS WEAR. BY SHRINIVASAN K
- 2. • Can be considered as steel girders for the purpose of carrying loads • Made up of high carbon steel to withstand wear and tear • Flat footed rails are mostly used in railway track 2 RAILS
- 3. FUNCTIONS OF RAILS 3 • Rails provide hard, smooth and unchanging surface for passage of heavy moving loads with minimum friction between steel rail and steel wheel • Rails bear the stresses developed due to heavy vertical loads, lateral and braking forces and thermal stresses • The rail material used is such that it gives minimum wear to avoid replacement charges and failure due to wear • Rails transmit the loads to sleepers and consequently reduce pressure on ballast and formation below
- 4. REQUIREMENTS OF RAILS • Rails should be designed for optimum nominal weight to provide for the most efficient distribution of metal in its various components 4
- 5. REQUIREMENTS (cntd..) 5 • The vertical stiffness should be high enough to transmit load to sleepers. The height of the rail should be adequate • Rails should be capable of withstanding lateral forces. Large width of head and foot provides the rail with high lateral stiffness • The depth of head of rail should be sufficient to allow for adequate margin of vertical wear. The wearing surface should be hard • Tensile strength of rail shouldn’t be less than 72 kg/m2
- 6. TYPES OF RAIL SECTIONS • Double headed rails • Bull headed rails • Flat footed rails 6
- 7. DOUBLE HEADED RAILS 7 • First stage of development of rails • 3 parts: – Upper table – Web – Lower table • Similar to dumb bell section • Both upper and lower tables are identical • When upper table was worn out, the rail can be reversed thus lower table can be brought into use • Practically out of use • Made of wrought iron • Length varying from 610 cm to 732 cm
- 9. • Made up of steel • Head is larger than foot • Foot is designed only to hold the wooden keys with which rails are secured to chairs • Extensively used in England • Weight of standard rail or British rail is 47 kg/m of length for main lines and 42 kg/m length on branch lines • Length of rail usually 18.29 m BULL HEADED RAIL 9
- 11. FLAT FOOTED RAIL • Foot is spread out to form a base • Invented by Charles Vignoles in 1836 and hence also known as “Vignoles Rails” • 90 % of railway track is made up of flat footed rails 11
- 13. WEAR ON RAILS • The moving of number of wheels of train on rail cause wear on rails • Depending on location wear of rail can be: – Wear of rails on top or head of rail – Wear of rails at ends of rail – Wear of rail on the sides of head of rail 13
- 14. Wear of rails on the sides of rail head 14 • Causes: • The wear on inner side of head of inner rail is due to slipping action of wheel on curves
- 15. • In India, prescribed limit for wear is 5 % of rail weight. • Allowable wear of 25 % of the section of head is also exceptionally adopted Allowable limits of wear 15
- 16. Methods adopted to reduce wear of rails 16 • Use of special alloy steel • Good maintenance of track • Reduction of expansion gap • Exchange of inner and outer rails on curves • Introducing check rails • Use of lubricating oil • Head hardened rails
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