Disc brake static friction coefficient

The article is devoted to the experimental study of the force interaction of the working elements of a disc brake in order to establish the dependence of the coefficient of static friction, taken as a criterion for the potential frictional properties of the friction unit, on the pressing force of the brake linings to the brake disc and the coefficient of mutual overlap. The experiments were performed on a full-scale stand, the basis of which is an electric drive with a power of 75.0 kW and a full-scale disc brake of the LT-10 tram. The stand allows to measure the static friction force under conditions of real forces, pressures, geometry of the contact area, as well as the coefficient of mutual overlap. TR119 and UT22-B were taken as friction materials for brake linings, in the first of which, according to the characteristics declared by the manufacturer, the coefficient of friction decreases with increasing temperature, in the second it increases. During the experiments, these materials worked in a pair of friction with the material steel 35, from which the brake disc is made. The experimental results were processed using the methods of mathematical statistics and presented in graphical form. It is shown that in the range of loads realized during braking, the stress-strain state of the contact area of the working elements of the disc brake according to the criterion of microstrains corresponds to an unsaturated elastic contact. This type of contact is typical for the studied overlap coefficients (0,33; 0,66; 0,98). It was found that with an increase in the pressing force of the brake linings to the brake disc, the static friction coefficient tends to decrease, and with an increase in the overlap coefficient, an increase in the static friction coefficient is observed for all specified values of the pressing force. At the same time, the UT22-V material is characterized by lower values of the coefficient of static friction compared to the TR119 material. Field of application of the results: development and design of advanced designs of disc brakes.