Method for determining the technical condition of telescopic shock absorbers.

The shock absorber is a key element of the car's suspension. Comfort, cornering stability and braking properties depend on its condition. In good condition, it must provide the necessary levels of damping for the relative displacement between the sprung and the unsprung mass of the vehicle. The reasons of a faulty shock absorber include a breach in the integrity of the seal between the different chambers, fatigue of the springs in the valve (piston) systems, plastic deformations in the working inner cylinder due to high temperature and mechanical stresses, etc. In the event of a shock absorber fault, usually there are no visual or noise changes to alert the driver. Therefore, the technical condition of the shock absorbers is often neglected. The visual inspection at annual tests of vehicle safety and roadworthiness does not give a satisfactory result. Expensive vibration stands are used to diagnose the technical condition of the shock absorbers, which also repels maintenance centers from such a purchase. The paper presents a comparative method that determines the technical condition of the shock absorber. For this purpose, the free damped oscillations of the sprung mass are recorded with measuring equipment at an affordable price. The measuring equipment includes an accelerometer, a DAQ-module and a laptop. The tyre is disturbed in the contact patch by artificial obstacles. Based on the logarithmic decrement of the oscillations, the damping coefficient of the suspension system is determined. Its value is an indicator for the technical condition of the shock absorber. [ABSTRACT FROM AUTHOR]