Railway Wheel Flat

Please READ MORE for the video. Do not think that this is a new type brake, this is sample of wheel flat. If there is a small flattened spot in wheel tread, it will be bigger flat in time due to impacts on its edges.

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Track and Rail and Wheel Physics and Rail Agglomeration Area and Moment Arm

Please READ MORE for the video (full secreen is my recommendation) and document. If there was not mass of railway vehicle and gravity, vehicle wheels stand just on rail head level. In fact due to physics, wheel embeds to rail and rail embed to superstructure and superstructur embed to substructure and earth (action-reaction) So, vertical and horizontal forces occur elastical deformation on wheel, rail and structure. As well as static wheel and dinamic (moving) wheel contact surface are different from each other. Wheel and rail contact area is not smooth flat, wheel is embeded to rail head due to wheel load and wheel gauge and wheel hardness and rail head hardness. Several deems accept wheel and rail contact surface has vertical force line passing through the center of the wheel (axle zero point on wheel). In fact, contact point is front of the center of the moving wheel (distance of static wheel-rail contact point as per moving wheel-rail contact point is named as moment arm). So, we can deem wheel always try to climb on rail due to whell-rail embeding ratio as well as climb on structure due to rail-superstructure-substructure embeding ratio as independently of the track vertical slope. Consequently, beside the driving resistances like bearing frictions, wheel-rail adhesion, aerodynamic resistances, vehicle power unit and power axles need to beat embeding resistance as well. This phenomenon makes strain on rail head surface on the back of the contact area and agglomeration on rail head surface on the front of the contact area. Furthermore, rail contact area tempreture increases because of vertical force (that force occurs pressure on surfaces and it energizes molecules which at the rail and wheel contact surface). We can calculate the train resistance through Equation of Davis. “We designate (V: km/h) as train velocity and (A: N) (B: Ns/m), (C: Ns^2/m^2) empirical coefficients. (A) is the mechanical resistance and determines due to axle load, number of axles and number of wagons naturally length of train, track and wagon type. (B) is the a part of the aerodynamic resistances so it is due to train lenght and number of axle. (C) is the aerodynamic resistances which affecting to front and rear area of the vehicle” [Rochard ve Schmid, 2000; Lukaszewicz, 2001]. On the other hand, we can calculate resistances with empirical methods like Traction Power Method, Dynomometer, Hump Release Method.

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