Arrangement for controlling the power transmission of a four-wheel-drive vehicle

摘要

An arrangement for controlling the power transmission of a four-wheel-drive motor vehicle has a clutch for transmitting the power to auxiliary drive wheels, transmitting devices for transmitting a radio-frequency wave to a surface of a road to locations in front of the vehicle and receiving devices for receiving the reflected wave. Comparison devices compare the received wave with the transmitted wave. When the difference between the amplitudes of the two waves exceeds a reference value, a control loop becomes effective in order to engage the clutch for the four-wheel drive. <IMAGE>