Device on a motor-driven vehicle to detect an obstacle in the way of the vehicle during backing

Claim 1

On a motor-driven vehicle having air brakes and quick-emptying brake valves releasing air on a braking operation a device to detect an obstacle in the way of the vehicle during backing, the device comprising in combination holders projecting backwards from each of the outer edges of the rear portion of the vehicle, one of which includes a transmitter for transmitting a pulsating light beam and one of which includes a receiver of such light beam, and means for mounting said transmitter and receiver on at least one of said holders for conveying the pulsating light beam between the holders for actuating said vehicle brakes when backing of the vehicle takes place and the light beam between said holders is interrupted by an obstacle external to said vehicle, means directed toward both holders comprising an air line fed with outflowing air from at least one of the quick-emptying valves of the vehicle on a braking operation for delivering a blast of air towards the holders to keep them free of dirt and the like which prevents transmission of the light beam between the holders.