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Traction can also refer to the maximum tractive force between a body and a surface, as limited by available friction; when this is the case, traction is often expressed as the ratio of the maximum tractive force to the normal force and is termed the coefficient of traction (similar to coefficient of friction).
Figure 1 Hard wheel rolling on and deforming a soft surface, resulting in the reaction force R from the surface having a component that opposes the motion. (W is some vertical load on the axle, F is some towing force applied to the axle, r is the wheel radius, and both friction with the ground and friction at the axle are assumed to be negligible and so are not shown.
The term tractive effort is often qualified as starting tractive effort, continuous tractive effort and maximum tractive effort.These terms apply to different operating conditions, but are related by common mechanical factors: input torque to the driving wheels, the wheel diameter, coefficient of friction (μ) between the driving wheels and supporting surface, and the weight applied to the ...
The reaction force on the wheels result in sliding friction. The coefficients for these equations are determined with experiments by measuring the tractive effort from the locomotive at different constant speeds or with a coasting experiments (the rail vehicle is set in motion at a certain speed and then the traction is disengaged, causing the ...
The circle of forces, traction circle, friction circle, [1] or friction ellipse [2] [3] [4] is a useful way to think about the dynamic interaction between a vehicle's tire and the road surface. The diagram below shows the tire from above, so that the road surface lies in the xy - plane .
The traction force, the braking forces and the centering forces all contribute to stable running. However, running friction increases costs, due to higher fuel consumption and increased maintenance needed to address fatigue damage and wear on rail heads and on the wheel rims and rail movement from traction and braking forces.
Slip ratio is a means of calculating and expressing the slipping behavior of the wheel of an automobile.It is of fundamental importance in the field of vehicle dynamics, as it allows to understand the relationship between the deformation of the tire and the longitudinal forces (i.e. the forces responsible for forward acceleration and braking) acting upon it.
In low traction situations, the total torque delivered to each wheel is limited to the torque that is required to make the wheel with the least traction slip. During a turn, the weight of the vehicle shifts away from the inner radius and to the outer radius, therefore the inner drive-wheel will often lose traction on hard cornering, and ...