Rolling resistance of mechanism with point and linear contact scheme

In most problems, mechanics rolling coefficient of friction either neglect or set its value without taking into account the contact patterns of the rolling bodies, their materials and sizes. Based on the theory of contact stresses by Hertz, analytical dependences are obtained that allow calculating the rolling friction parameters with the greatest reliability in comparison with the analogues of other authors. But in the Hertz formulas, the parameter hysteresis loss coefficient is introduced, the determination of which requires time and money no less than obtaining the value of the rolling friction coefficient itself. This makes it impossible to use them in engineering practice to determine the magnitude of the friction force, and, accordingly, the coefficient of performance (COP) of a number of mechanisms with rolling. This leads to the fact that the drive power of the mechanisms has to be overestimated due to the uncertainty of its efficiency. The purpose of the article. To determine the efficiency of widely used mechanical devices in which rolling friction is present. In accordance with the stated goal, in the process of studying the operation of devices it is necessary to use only generally accepted mechanical constants and sizes. Conclusions. The efficiency of crab traverse mechanism does not depend on the direction of load application of movement relative to the direction of motion. The efficiency of conical friction gear depends on the coefficient of rolling friction, assumed contact voltage and elastic modulus. The proposed analytical dependences for determination of the coefficient of rolling friction in the ball guide allow us to resolve the total resistance into the rolling and sliding and conduct measures to reduce the more significant component. The main component of the motion resistance in the ball guide is a component of slide friction and it is a minimum at the angle of opening guide 2α = 90°.