Patent ID: 7913801
Filing Date: 2011-03-29
Classification: B62D,E02F

Abstract:
1. A steering system for a construction vehicle, said steering system being provided with steering hydraulic cylinders as actuators for performing steering of said vehicle, a pilot-operated directional control valve for controlling a direction and amount of pressure oil to be fed to said steering hydraulic cylinders, and a steering-wheel-operated signal generation means provided with a rotationally-operable steering wheel such that by rotational operation of said steering wheel, a pilot signal is generated to switch an operated position and opening area of said pilot-operated directional control valve, wherein said steering system comprises a lever-operated signal generation means provided with a tilt-operable steering lever to generate by tilt operation of said lever a pilot signal for switching the operated position and opening area of said pilot-operated directional control valve, selector valves switchable such that the pilot signal from the steering-wheel-operated signal generation means or the pilot signal from the lever-operated signal generation means can be selectively outputted to said pilot-operated directional control valve, a lever-operated manual switching means for switching said selector valves such that by manual operation, the pilot signal from said lever-operated signal generation means can be outputted to said pilot-operated directional control valve to permit steering said vehicle by tilt operation of said steering lever, and an automated switching means for preferential control by said steering wheel to automatically switch said selector valves such that upon rotational operation of said steering wheel, the pilot signal from said steering-wheel-operated signal generation means can be outputted to the pilot-operated directional control valve even when said selector valves have been switched by the manual operation of said manual switching means to permit outputting the pilot signal from said lever-operated signal generation means to said pilot-operated directional control valve.