PRESSURE OSCILLATION IN HYDRAULIC HITCH-SYSTEM DURING IMPLEMENT TRANSPORT

Abstract

This paper presents results of pressure oscillation investigation in tractor Claas Ares ATX 557 hydraulic hitch-system, loaded with disc harrow, during the motion around artificial roughness test road. During experiments oscillation at the different drive speed, tires pressure and hitch-system oscillation damping (turned on or off) were investigated.
Tractor hydraulic hitch-system was equipped with pressure sensor and data processing software. Results of experiments present maximum pressure peak 188 bar in tractor hydraulic system, if not used hydraulic hitch-system oscillation damping system at driving speed 8 km h-1, and if used hydraulic hitch-system oscillation damping system pressure peak reduced to value 170 bar. Simulation of tractor movement with attached disc harrow over rough surface with Working Model software was used. Hitch-system cylinders were replaced as coupler with spring and damper characteristic in model. Dynamic force on coupler was obtained as simulation result and depending on it hydraulic pressure in hitch-system cylinder had been calculated. Simulation results were evaluated on basis of experimental investigations. Reducing of hydraulic cylinder stiffness value let to reduce pressure value to 168 bar at driving speed 8 km h^-1 during simulation.