System for controlling a power transmission of a four-wheel drive vehicle

摘要

A system for controlling a power transmission of a four-wheel drive vehicle powered by an engine has a transmission for transmitting the power of the engine to main driving wheels of the four-wheel drive vehicle, a hydraulically operated clutch for transmitting the power to auxiliary driving wheels, a hydraulic circuit for operating the clutch in accordance with driving conditions. The system comprises a sensor for detecting the inclination of roads and for producing an output signal dependent on the inclination, and a control circuit responsive to the output signal from the sensor for engaging the clutch when the output signal exceeds a predetermined value, thereby establishing the four-wheel drive.