Patent ID: 8087489

Claim:
An articulated construction vehicle provided with a self-propelled body with a front frame and a rear frame connected together rotatably relative to one another in a horizontal direction such that said self-propelled body can be articulated, body-articulating hydraulic cylinders selectively extendable or retractable such that said front frame can be driven to rotate relative to said rear frame in the horizontal direction to articulate said self-propelled body, a pilot-operated directional control valve for controlling a direction and amount of pressure oil to be fed to each of said body-articulating hydraulic cylinders, and a steering-wheel-operated control device provided with a rotationally-operable steering wheel such that by a rotational operation of said steering wheel, a pilot signal can be outputted to corresponding one of signal-receiving ports of said pilot-operated directional control valve to switch an operated position and opening area of said pilot-operated directional control valve, characterized in that said articulated construction vehicle is constructed by being provided with a lever-operated, electrical control device provided with a tilt-operable lever to output an electrical signal by tilt-operation of said lever, a controller for being inputted with the electrical signal from said lever-operated, electrical control device to output an electrical signal concerning a direction and amount of the operation of said lever, a signal conversion means for converting the electrical signal from said controller into a corresponding pilot signal and outputting the pilot signal to corresponding one of said signal-receiving ports of said pilot-operated directional control valve, and a selection means of an operation system that operation of said pilot-operated directional control valve by the rotational operation of said steering wheel in said steering-wheel-operated control device and operation of said pilot-operated directional control valve by the tilt-operation of said lever in said lever-operated, electrical control device can be selectively performed, wherein pressure sensors for detecting existence or non-existence of a pilot signal outputted from said steering-wheel-operated control device are arranged to feed detection results from said pressure sensors to said controller, and, when said controller determines, based on the detection results, that the pilot signal has been outputted from said steering-wheel-operated control device, control is performed to disable operation of said pilot-operated directional control valve by a tilt operation of said lever of said lever-operated, electrical control device.