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, and a clutch for transmitting the power to auxiliary driving wheels. A hydraulic circuit and a solenoid operated valve are provided for operating the clutch. First sensors are provided for detecting the speed of the main and auxiliary driving wheels, respectively, and second sensors are provided for detecting depression of an accelerator pedal and depression of a brake pedal of the vehicle respectively. When a large difference between the speed of the wheels is detected, the clutch is engaged, and when a large acceleration and large deceleration dependent on the output of the first sensors are detected, the clutch is engaged for establishing the four-wheel drive.