Motor vehicle front wheel drive transmission system with optional drive to rear wheels - has engine driven hydraulic pump with rear wheel hydraulic motors and auxiliary top-up pump

摘要

The engine (1) drives a conventional mechanical gearbox (2) to drive the front wheel transmission (4). When selected by the driver, a constant-volume hydraulic pump (13) supplies through a flow balancer (17) two constant-volume hydraulic motors (23, 24), each driving a rear wheel (27, 28). Pressure limiters (33, 34) working in opposite directions control the pressure difference between pump and motors. The engine (1) drives an auxiliary pump (47) feeding a manually operated controller (45) which discharges either to the reservoir (50) or to the line (41) and the non return valves (38, 39) to top up the main system and prevent cavitation of the pump (13). ADVANTAGE - The system will drive the rear wheels in either direction, with differential drive between front and rear wheels.