PORTABLE TYRE TEST RIG FOR INVESTIGATION OF PHYSICAL PARAMETERS OF AGRICULTURAL AND CONSTRUCTION MACHINERY TYRES UNDER CRITICAL ON-ROAD CONDITIONS

摘要

This study describes a new portable tyre test rig that enables investigation of mechanical properties of tyre and tyreto-ground characteristics on various surfaces. The test wheel is mounted to a frame which is pulled behind the tractor. The tyre represents the spring-damper element and, together with the frame and its variable weight, represents a single-mass oscillator. Analysis of a quarter of the vehicle enables investigation of vertical stiffness and damping ration by two methods: first, step response and, second, by random vibration excited by road unevenness. The test wheel is mounted to the six component measurement device that enables measurement of acting forces and torques in the centre of the wheel. The test wheel is mounted in such a way that it is possible to change slip and camber angle. Additionally, the braking moment can be applied by wet-brakes. The whole portable tyre test rig helps to investigate tyre-ground interactions under various dynamic transient processes. The second elementary test measures step response of lateral force under different conditions. These dependencies have significant meaning for transferring lateral forces, and as a consequence handling and driving safety.