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Defects in rails. Railway Engineering
- 1. DEFECTS IN RAILS Railway Engineering Transportation Engineering
- 2. DEFECTS IN RAILS Subject:Transportation Engineering Topic: Railway Engineering SubTopic: Defects in Rails Slides presented by Irfan Nasir F16CE-79 2ndYear, 3rd Semester Section-C Department of Civil Engineering SubjectTeacher: Mr.Abdul Raqeeb Memon Mehran University of Engineering &Technology Jamshoro Sindh Pakistan
- 3. Corrugated Rails In certain places, the heads of the rails are found not straight but corrugated i.e., with a wavy surface.This phenomena is called Corrugation and the rails are called Corrugated Rails.
- 4. Examples from a metro system and from the UK main-line railway are shown in Figs 3 and 4
- 5. Occurrence Corrugation occurs primarily in straight track and gentle curves, where curving is undertaken with minimal flange (rim) contact. It is more likely to occur on the high than on the low rail in curves and is associated also with track carrying relatively light axle load traffic, i.e. <20 ton. In long tunnels along a track. On electrified section of a railway track If ballast consists of broken bricks, chances of corrugation are high
- 6. Causes The phenomena of corrugation is complex and it is not possible to mention the specific causes. The following are possible factors which cause corrugation 1. Coning of engine wheels 2. Excessive slack or excessive tight gauge. 3. High speed of trains. 4. Non-uniformity of the diameter of engine wheels. 5. Presence of high humidity and dust in the atmosphere 6. Slipping of wheels of engines, 7. Small spacing between driving axles of the locomotives, 8. Steep gradient, 9. Sudden application of brakes, 10. Use of light wagons and coaches, 11. Use of steel having high nitrogen content and high tensile strength 12. Soft ballast 13. Vibration during rolling of rail section, etc Conning is done to maintain the vehicle in the central position with respect to the track. More info on conning https://civilcompanion.wordpress.com/2016/08/09/c oning-of-wheels/
- 7. Examples of Corrugation For more information regarding corrugation visit http://railmeasurement.com/assets/docs/090709-JRRT-corrugation.pdf
- 8. Hogged Rails ■ The rails which are bent vertically at the ends are known as hogged rails and they are formed due to wear of rails on ends.
- 9. Causes Due to battering action of wheels over the end of the rails, the rails get bent down and get deflected at the ends. Battering action To damage, as by heavy wear:
- 10. How to rectify Hogged Rails 1. Cropping The hogged rails should be removed and replaced by new rails. However this will be very uneconomical. But some economy is achieved by using hogged rails on some unimportant lines
- 11. How to rectify Hogged Rails 2. Replacement The end portion of the rail is cut-off and fresh holes are provided for fish-plates and new rails are attached.This cutting can be done either at depot or at site. This is done when the cropping is not sufficient and if due to cropping the length of track is shortened.
- 12. How to rectify Hogged Rails 3.Welding Can also be improved by welding the worn ends of the rails.
- 13. The hogged rails can be improved or straightened by some simple device such as dehogged maching. It consists of a 1. Bottle jack 2. Length of old rail 3. Two sets of clamps Note: It is used only when damage of track is not large How to rectify Hogged Rails 4. Dehogging More info http://www.brainkart.com/article/Dehogging-of-Rail Ends_4303/
- 14. Buckling of Rails Buckling means the track has gone out of its original position or alignment due to prevention of expansion of rails in hot weather on account of temperature variations.
- 16. Precautions The expansion gap should be sufficient, The fish bolts should not be tightened up to such an extent as to prevent expansion or contraction of rails The contact surfaces between the fish plates and rails should be periodically lubricated,. Precautions should be taken to reduce the creep, Causes of Buckling Insufficient expansion gape Excessive tightness of the joint
- 17. Creep in Rails Creep in rail is defined as the longitudinal movement of the rails in the track in the direction of motion of locomotives. Creep is common to all railways and its value varies from almost nothing to about 6 inches or 16cm. More info on creep http://www.engineeringarticles.org/wh at-is-creep-in-rail/
- 19. Results of Creep Sleepers move out of the position Gauge disturbance Gap variation at joints and other parts, results in uneven stresses Points and crossings will be disturbed Difficult to refix rail with creep Interlocking mechanism also gets disturbed
- 20. Split Heads In this type of failure, the head of rail is split up into two parts. If the surface of cracks appears smooth and dark, when opened, the defective rail is known as piped rail and is due to cavity formed during manufacture. The vertical split head (UIC 113, 213) type of defect can be ascribed mainly to metallurgical problems in the production of the rails. More info on split heads http://www.eurailscout.c om/services/rail/- vertical-split-head- detection/
- 21. Vertical Split Heads cond… Steel production methods used in the past, such as theThomas process generate a higher concentration of phosphorus, Sulphur, nitrogen, manganese and hydrogen in the vertical plane of symmetry of the rail. If there are additional inclusions present in this level when the steel is produced, then this may lead to the formation of cracks in the rail over a length of up to 120 meters and thus to the breakage of the rail head over a great length.Thus, the vertical split head must be ranked as one of the most dangerous rail defects.
- 22. Transverse Fissures This is developed in the form of a fissure or a hole in the head of a rail. It is in the form of a cross-wire crack which starts from a point inside the head and exhibits a sooth oval or round bright spot. Causes It is due to defect of manufacture or due to overstraining of metal in service. This defect is dangerous in the sense that the rail breaks before the defect becomes visible causing the failure of the track
- 23. In this type of failure, a fissure is developed in the section of the rail and it gradually goes on increasing. It is due to worn fish plates or insufficient ballast packing under the joint sleepers. Horizontal Fissure
- 24. THE END ThankYou for your attention