A trailer brake system constructed and arranged to effect the relay of a brake signal from the tractor and an automatically generated brake signal of an electronic control device of the trailer to one or more additional trailers in an expanded vehicle train. In one embodiment, the brake signal is relayed to an additional coupled trailer in the form of an electrical signal via an electrical interface. In another embodiment, the brake signal is relayed to an additional trailer by means of a valve device. In yet another embodiment, the brake signal is relayed to an additional trailer by means of a combination of electrical signal transmission and valve device.