Assessment of the Influence of Braking Devices over the Stability of Braking Properties of the Vehicles

The paper is devoted to the study of the influence of braking devices over the stability of braking properties of the cars. A technique is proposed for assessing the stability of braking devices using the generalized braking torque equation, which allows the selection of a rational type of braking devices and optimization of the geometric parameters thereof at the design stage of the cars. Stability assessment of the braking torque is carried out according to the criterion of the sensitivity of the braking torque to a change in the coefficient of friction between the friction surfaces of the braking mechanism. Using the dimensionless functions and coefficients depending on the geometric parameters of the friction pairs and the feedback sign in the braking mechanism, it was found that the braking mechanism with one active and one passive pad has less sensitivity to a change in the friction coefficient than the braking mechanism with two active pads. The analysis of the influence of the nonuniformity of the braking forces on the wheels of a certain axis of the car over the deviation of the distribution of braking forces between the axles from its calculated value has been performed. When assessing the error in regulating the distribution of braking forces between the axles of the car, three components were taken into account: theoretical error due to the imperfection of the selected control method (the difference between the actual calculated control characteristic and the ideal one), the error created due to the instability of the ratio of braking forces on the front and rear wheels, and an additional error due to the unevenness of the braking forces on the wheels of individual axles. The proposed method allows assessing the quality of regulation of the distribution of braking forces between the axles of the car, taking into account the instability of the braking forces on the wheels.