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Rolling resistance, sometimes called rolling friction or rolling drag, is the force resisting the motion when a body (such as a ball, tire, or wheel) rolls on a surface. It is mainly caused by non-elastic effects; that is, not all the energy needed for deformation (or movement) of the wheel, roadbed, etc., is recovered when the pressure is removed.
Hertz solved the contact problem in the absence of friction, for a simple geometry (curved surfaces with constant radii of curvature). Carter considered the rolling contact between a cylinder and a plane, as described above. A complete analytical solution is provided for the tangential traction.
A starting point for solving contact problems is to understand the effect of a "point-load" applied to an isotropic, homogeneous, and linear elastic half-plane, shown in the figure to the right. The problem may be either plane stress or plane strain. This is a boundary value problem of linear elasticity subject to the traction boundary conditions:
rolling friction. In the case of bodies capable of rolling, there is a particular type of friction, in which the sliding phenomenon, typical of dynamic friction, does not occur, but there is also a force that opposes the motion, which also excludes the case of static friction. This type of friction is called rolling friction.
The basic model equation for SAE J2452 is: Rolling Resistance (N / Lbs) = P α Z β (a + bV + cV 2) where: P is the tire inflation pressure (kPa / psi) Z is the applied load for vehicle weight (N / Lbs) V is the vehicle speed (km/h / mph) alpha, beta, a, b, c are the coefficients for the model. The units of the coefficients are matched to the ...
The friction coefficient is an empirical (experimentally measured) structural property that depends only on various aspects of the contacting materials, such as surface roughness. The coefficient of friction is not a function of mass or volume. For instance, a large aluminum block has the same coefficient of friction as a small aluminum block.
Schematic of quantities for capstan equation An example of holding capstans and a powered capstan used to raise sails on a tall ship. The capstan equation [ 1 ] or belt friction equation , also known as Euler–Eytelwein formula [ 2 ] (after Leonhard Euler and Johann Albert Eytelwein ), [ 3 ] relates the hold-force to the load-force if a ...
This may be the reason why the minimum in the coefficient of friction for a liquid-lubricated journal bearing was not discovered by him, but was demonstrated by the graphs of Martens and Stribeck. The graphs plotted by Martens show the coefficient of friction either as a function of pressure, speed or temperature (i.e. viscosity), but not of ...