Dual directional and brake light control for trailers

Abstract

A device for adapting combined brake and turn signal lights on a trailer to independent brake signal and turn signal lights on a towing vehicle has two circuits, one for each side, each circuit having a brake signal switch, such as a transistor, silicon-controlled rectifier or relay connected between the brake signal circuit of the vehicle and the filament of the combined brake and turn signal light on the corresponding side of the trailer. The brake signal switches are selectively actuated by impulses received from the corresponding turn signal flashers on the vehicle, to block the brake signal current to the corresponding signal light on the trailer. In one embodiment of the invention, voltage-sensitive switches (e.g., SCR) are connected to brake switch transistors, and the left-hand and right-hand turn signal circuits on the vehicle are connected through diodes to the corresponding signal lamps on the trailer, and also to their respective switches. When brakes are applied and turn signals simultaneously operated, the flashing turn signal triggers the voltage-sensitive switch on that side, causing the transistor to switch off, which prevents the brake circuit from lighting the combined lamp filament on that side while the filament is being flashed by the turn signal. The lamp on the other side remains lighted by the brake circuit. In another embodiment, relays or transistors are connected to the turn-signal circuits and brake signal circuits on each side of the towing vehicle in such a way that when one turn signal is operating the brake signal for that side is blocked by the turn signal voltage, and is passed when the turn signal voltage is off. Thus, the trailer turn signal lamp on the one side blinks at the same rate as the turn signal lamp on the vehicle, but 180.degree. out of phase with the latter.