This paper also observes the variations in surface roughness and hardness of the wheelrail discs for the sliding distance in each. Steel mechanical engineering, school of engineering and physical sciences, heriotwatt university, riccarton, edinburgh, scotland eh14 4as uk abstract abnormal contact stresses between wheels and rails can give rise to excessive rail wear and. Influential factors on adhesion between wheel and rail. Lowering the friction at the wheelrail interface drives the fatigue defect formation subsurface, however. The relationship between vertical wear rate and crack length reduction depends on the angle of the crack below the rail surface. Geared devices can change the speed, torque, and direction of a power source. Understanding the effects of track gauge, wheelrail geometry.
What is the size of the contact surface of train wheels. Typically three reprofilings before scrapping of the wheel damage time. The in service properties therefore vary with depth below the surface and with position across the wheel tread. Traces of cast iron, previously transferred from the brake specimens to the wheel ones, were detected. Thermal load effects on fatigue life of a cracked railway. Winspect is able to automatically inspect wheel sets using high definition cameras and adhoc illuminating system. This accelerates the socalled useful wear which is necessary for acceleration of runningin ability process in the system wheel. Associated risks and maintenance strategies technical report by saurabh kumar division of operation and maintenance engineering lulea railway research center jvct lulea university of technology, lulea, sweden. Simple search advanced search research publications advanced search student. Hardening after thermochemical surface treatment carburizing, etc.
The tribofatigue damage transition and mapping for wheel. Contact fatigue damage frequently occurs on the surface of gear teeth and steel making. Consequently, it is expected that surface cracks are more likely to initiate when the wheel is towards the end of its life, after wear and turning have removed material owing to the nearsurface material having a lower hardness and higher proportion of pe ferrite. How to ensure train track security and keep it stay away from steel rail wear. Fatigue cracks initiate on the wheel specimen surface. This specification details the allowable limits for the inspection of all rail vehicle wheels for various tread and flange defects. The wheel tyre is coned and the rail head slightly curved as shown in figures 2 and 3. Wear of wheels occurs on the wheel tread and flange. Rail grinding and its impact on the wear of wheels and rails. Additional propagating factors may be external pollution, such as sand, dust, water etc. Lightly sprinkle a small amount of the collected bakelite filingsdust into the veed out areas. Effect of plastic deformation in surface layer of wheel.
Surface metallurgy and rolling contact fatigue of rail. This can be used because a competition exists between wear and surface initiated rcf. Grinding of the rail head is another, though more expensive, means to address this issue. Every effort should be made to avoid the abnormal loss of tread metal caused by thermal cracking and shelling. I prefer geltype ca glues, as they are less prone to run. Surface cracks in the form of headchecks could be noted on the surface of the new 1100 grade rails after 1 month of traffic. Damage is considered to be either already present i. Rcf initiated problems such as surface cracks, head checks, squats, spalling and shelling. Wheel reprofiling owing to surface cracks andor unacceptable geometry, wheels are reprofiled. The area of surface contact varies when the locomotive or car is in motion depending on steady state forces and other external forces when in motion. Feb 02, 2009 the area of surface contact varies when the locomotive or car is in motion depending on steady state forces and other external forces when in motion.
The contact between wheels and track is fundamental to railway operations, but the contact conditions are affected by often unpredictable external sources of contamination such as fallen tree leaves, snow and rain which can substantially reduce the level of adhesion of the track that is essential to the delivery of tractive effort for traction and braking systems in railway vehicles. Wheelrail wear and surface damage caused by adhesion sanding. Surface railway definition is a railway whose tracks are mainly on the surface rather than beneath it as in a subway or above it on a superstructure as in an elevated railway. In order to keep the contact fatigue stresses to a minimum, maintenance managers must ensure that the rail makes contact with the best mating surface on the wheel for the entire length of the train. Stress intensity factor for initial surface micro crack. Vee out cracks i like to open the cracks up to at least 18 with a vshaped file, being very careful to save the dustshavings.
R8t wheel steel wear rates and regimes from 18 at low t. Surface railway definition of surface railway by merriam. Oct 19, 2010 rail and wheel wear reduction posted by jacknbox on tuesday, october 19, 2010 11. Rolling contact fatigue an overview sciencedirect topics. More precise simulation requires sawtooth like pulses where analytical calculation of the. Teeth on a wheel crossword clue answer crossword heaven. The inservice properties therefore vary with depth below the surface and with position across the wheel tread.
Effect of shoe braking on wear and fatigue damage of. Understanding the effects of track gauge, wheelrail. Experimental study on wear and spalling behaviors of railway. Jul 22, 2010 wear of wheels occurs on the wheel tread and flange.
Simulation and measurement of wheel on rail fatigue and wear. Magneticparticlendt a magnetic field is applied across the. Detection of wheelrail contact conditions for improved. Allowable speeds mentioned below are not to exceed the prevailing track speed limit. Angle of attack is one of the most important parameters influencing wheel and rail wear. Based on the data, the paper has counted the development of the rail profile wear, and then analyses the influence of wheel rail contact geometry on the rail profile wear. Wear of the surface of a rail can be beneficial in removing small cracks, and by slowing the effective crack growth rate for larger cracks. A 3d femodel was constructed in abaqus to simulate the stressstrain fields that take place under the rollingcontact of railway wheels on rails. The objective of this paper is to investigate the wear and. The text outlines the action to be taken when defects are found. Trbs transit cooperative research program tcrp report 71, trackrelated research, vol. Rail wheel interface rail wheel interface systems focus on understanding the dynamic interaction between the rail wheel and the rail while the vehicle is in motion. The results show that the wear of high rails develops around the rail corners, while the one of low rails around. Thermal load effects on fatigue life of a cracked railway wheel.
In order to keep the contact fatigue stresses to a minimum, maintenance managers must ensure that the rail makes contact with the best mating surface on. Quantifying rail surface damage wheel rail interaction. As a result actions on how to reduce wheelrail wear and profile changes may be proposed. Quantifying rail surface damage 18 dye penetrant and magnetic particle ndt dye penetrant ndt the rail is coated by a dye formulated to penetrate cracks. Study on the adhesion characteristic between wheel and. In this section, the following issues related to wheelrail profiles and wheelrail interactions are discussed. Radial fatigue crack had origin at the bearing surface 14 reproduced by. Shaffer, battelle laboratories contact fatigue is a surfacepittingtype failure commonly found in ball or roller bearings. Because shelling cracks are oriented at 30 to 50 deg to the tread surface they are assumed to be caused by high shear stresses developed by rolling loads. After cleaning dye from the surface, a white developer powder is sprayed that draws dye from within the cracks. As is known, friction plays a vital role in wheel and rail wear 2,3,9,10 and investigations and applications have indicated that lubrication of the wheelrail contact is an effective method for. System transition in increasing wheel flange angle. Steel rail is the fixed road of train running, so its safety is very important for train. This way, many different wheelrail contact conditions which a wheel or a rail will encounter in reality can be taken into account.
Shaffer, battelle laboratories contact fatigue is a surface pittingtype failure commonly found in ball or roller bearings. The main conical surface allows centering wheel pair in fixed tracks and facilitates the passage curves sections of track without slipping and excessive wear. Lewis and dwyerjoyce 8 studied the wear and sur49 face. Pdf surface fatigue of gear teeth flanks researchgate. Abnormal wheel motion patterns can be caused because of poor rail profile or poor track geometry leading to damage to both wheels as well as the rails.
When traversing a curve, the angle of attack changes where leading wheel of. Rail and wheel wear reduction trains magazine trains. Wear rates in these two regions depend on a variety of factors, such as the vehicle design, the service profile e. Pdf monitoring of railwheel interaction using acoustic emission. Rail profile wear on curve and its effect on wheelrail. The main damage phenomena observed in the specimens subjected to wheel brake contact and dry wheel rail contact were ratcheting, wear and nucleation of surface cracks. However, it is necessary and significant for clarifying the mechanism and relationship between the wear and spalling damage of railway wheel to test and reproduce the wheel damages in laboratory.
This paper also observes the variations in surface roughness and hardness of the wheel rail discs for the sliding distance in each. The influence of wheelrail contact conditions on the. Wheel rail interface rail adhesion from wikipedia, the free encyclopedia. These are formed when plastic deformation is constrained by the surrounding material, and is more common when shear stresses are extremely high. Jan 16, 2014 the susceptibility of railway wheels to wear and rolling contact fatigue damage is influenced by the properties of the wheel material. These are influenced by the steel composition, wheel manufacturing process, and thermal and mechanical loading during operation. This thesis concerns the influence of surface roughness of wheelrail surfaces on runningin behaviour. Gears almost always produce a change in torque, creating a mechanical advantage, through their gear ratio, and thus may be considered a simple. As a consequence of this complex wheelrail contact condition, two distinct wear regions appear on the wheel profile. Carefully pour a small amount of ca glue into the crack. The paper has carried out continued tests on a curve of a heavy haul railway in china for its rail profiles. The wear calculations were refined and the contact model improved by considering the. Lowering the friction at the wheel rail interface drives the fatigue defect formation subsurface, however. Those parameters are running speed, water temperature, wheel load and surface roughness of wheel and rail which have great influence on hydrolubricate behavior of water film formed at wheelrail interface from the tribological point of view.
Fatigue of rails and wheels center for railway research. This possibility is exacerbated if the wheel tread is moderately or extremely hollow worn with the development of a false flange on the outside edge of the tread. Method for repair of rail wheels general electric company. Use of steels with limited hardenability in cases 2,3 the whole gear or tooth area may be heated to austenization temperature and quenched. This type of failure can also be found in gears, cams, valves, rails, and gear couplings. As the name suggests, these excavators use a huge wheel fitted with from eight to 24 or more buckets to continuously dig and dump coal andor overburden. Brinksma, volgens besluit van het college voor promoties in het openbaar te verdedigen op vrijdag 19 februari 2010 om 15. Abnormal wheel motion patterns can be caused because of poor rail profile or poor track geometry leading. A gear or cog is a rotating machine part having cut teeth or, in the case of a cogwheel, inserted teeth called cogs, which mesh with another toothed part to transmit torque. The main goal of this phd work was to develop such a tool where vehicletrack dynamics simulations are implemented. Surface metallurgy and rolling contact fatigue of rail white rose. Wheel and rail wear understanding the effects of water. Wheel damage wear wear occurs from sliding between the wheel and rail, typically in the flange root area benign slow process.
Flange directs the movement of the wheel on the rail track and prevents the wheelset of derailment. Trains the railway technical website prc rail consulting ltd. The wear prediction part of the tool had already been successfully. According to the united states federal railroad administration office of safety analysis, 1 track defects are the second leading cause of accidents on railways in the united states. Surface contact fatigue failure of a case hardened pinion shaft. This can be minimized by correct alignment of the wheels, flange lubrication, material of wheel and rail being similar and equipment in proper mechanical condition. It is known that impact, wear and cracking generate ae and it is. Flange climb derailment criteria and wheelrail profile. Defects on the running surface of the wheels, such as shelling, spalling, flat spots, etc. However, in modern highspeed and heavyhaul railway networks, wear and fatigue damage for wheel. Jan 04, 2014 lowering the friction at the wheel rail interface drives the fatigue defect formation subsurface, however. Introduction friction at railwheel interface is a significant parasitic energy loss. Based on the data, the paper has counted the development of the rail profile wear, and then analyses the influence of wheelrail contact geometry on the rail profile wear. This thesis concerns the influence of surface roughness of wheel rail surfaces on running in behaviour, wear, friction and resultant surface damage.
Surface contact fatigue failures in gears 101 rolling contact fatigue leads to the formation of a microstructural feature referred to as butterfly wings 3. Too high wear is monitored by geometry measurements. Effect of plastic deformation in surface layer of wheel rim. The effects of wheel and rail surface features appear to complicate. If the smaller wheel of the contacting pair, called the pinion shaft, is in the engine, the gear train will reduce. Experimental study on wear and spalling behaviors of. Rail inspection is the practice of examining rail tracks for flaws that could lead to catastrophic failures.
This way, many different wheel rail contact conditions which a wheel or a rail will encounter in reality can be taken into account. This is caused by normal wheel rolling along the railhead and is a relatively newly diagnosed phenomenon. Picture a tall ferris wheel where the seats are replaced with buckets and you. Rail and wheel wear reduction trains magazine trains news. Macroscopic examinations of radialtangential sections from shelled areas have indicated that shelling is caused by cracks that form at angles of 30 to 50 deg to the tread surface. The results presented in this thesis are based on both field measurements and experimental simulations in the laboratory. Wheel and rail wear understanding the effects of water and. Study on the adhesion characteristic between wheel and rail. Wear and fatigue of railway track caused by contamination. On larger machines the wheel measures up to 20 meters 66 feet in diameter. This accelerates the socalled useful wear which is necessary for acceleration of runningin ability process in the system wheelrail. As a result, the wheels surface is weakened, and the stress field in the area of contact with the rail may cause microcracks. The current researches of the wear and spalling behaviors of wheelrail materials focus on the field investigation rather than the mechanism.
As is known, friction plays a vital role in wheel and rail wear 2,3,9,10 and investigations and applications have indicated that lubrication of the wheel rail contact is an effective method for. As the name suggests, these excavators use a huge wheel fitted with from eight to 24 or more buckets to continuously dig and dump coal and or overburden. This causes stress in the head of the rail which can lead to small cracks which can then develop into complete fractures. Wheelrail wear and surface damage caused by adhesion. In rolling contact fatigue of rails, cracks form at a shallow angle, and grow. Nov 20, 20 the current researches of the wear and spalling behaviors of wheel rail materials focus on the field investigation rather than the mechanism. When traversing a curve, the angle of attack changes where leading wheel of leading truck comes in contact with the rail. Contact fatigue has been identified in metal alloys both. What is the size of the contact surface of train wheels and.
This thesis concerns the influence of surface roughness of wheelrail surfaces on runningin behaviour, wear, friction and resultant surface damage. At a high wear rate, rcf does not have the opportunity to develop further. Closer examination of the wear surface of the wheel. Flange climb derailment criteria and wheelrail profile management and maintenance guidelines for transit operations examines flange climb derailment criteria for transit vehicles that include lateraltovertical ratio limits and a corresponding flangeclimbdistance limit. The susceptibility of railway wheels to wear and rolling contact fatigue damage is influenced by the properties of the wheel material. Steel rail wear is a common but dangerous phenomenon that impacts the train track safety. As of 2005, the aar set a hollow wear limit for wheel treads of 4 mm. The reason for this reduction can be basedon the fact that during rotation of the wheel on the rail, a new rail surface is always subjected to the high temperature wheel surface. The objective of this project is to provide an adequate numerical assessment of the sub surface crack initiation and propagation in railway wheels. Surface contact fatigue failure of a case hardened pinion. Rail grinding and its impact on the wear of wheels and. By contrast, the surface of the uic 900a grade rails showed visible surface cracks in only two of four curves and that after approximately 2 years of traffic.