Study On System Performance Of Composite Mechanical And Hydrostatic Drive

Special Purpose Vehicles which are mainly applied under the circumstances such as roadmaintenance and constructions, have high speed requirement in non-working conditions,while have low speed requirement as supplementary in working conditions, especially whenvehicles under low speed could acquire lower speed and better stability. It is thus clear thatthe characteristic of the Special Purpose Vehicles’ driving system is the key factor that affectsthe performance of the vehicle.This paper deals with Special Purpose Vehicles’ driving system at home and abroad.Four kinds of driving schemes are raised and synthetically compared. The driving scheme,which composite mechanical and hydrostatic by adding composite transmission box betweenthe engine and the gearbox, is adopted. This scheme used mechanical drive under the workingconditions of transport running and hydraulic drive under the working conditions of operating.Closed hydraulic system, which combined variable pump and quantitative motor, is adopted.The tractive characteristic and the efficiency of the pump and motor are analyzed. This paperalso made several selections in some of the device and analyzed the dynamic response of themathematical model of the variable pump and quantitative motor. This paper simulated thehydraulic system of the Special Purpose Vehicles under low speed using the hydraulicsimulation software AMESim, and analyzed different displacement ratio, time response,typical load and the working device’s influence on the driving system.The result of the simulation of the driving system is coincided with the theoreticalcalculation result. And a large scale of low speed in working conditions is realized. TheOperating speed, power and torque of the Special Purpose Vehicles could be reached. Thefeasibility and the practical applicability of the driving scheme which composite mechanicsand static pressure is affirmed.