Load-dependent trailer brake system and method of controlling such

A trailer brake system comprising a brake actuator connected to a pressure source via a pressure-controlled relay valve having a first control port which is connected to a command line via a pressure-controlled load sensing valve, wherein the load sensing valve comprises a second control port connected to a control line via an electrical proportional valve, and an electronic controller in communication with the proportional valve and configured to generate a load-dependent control signal from trailer load information for controlling the proportional valve, wherein the load sensing valve is operable to open under positive pressure at the second control port, and wherein the load sensing valve is operable to maintain a non-zero minimum open parameter in the absence of a positive pressure at the second control port.

A method of controlling a trailer brake system comprising receiving trailer load information, generating an electronic load-dependent control signal based upon the trailer weight information, and controlling an electrically-controlled proportional valve with the load-dependent control signal, wherein the proportional valve is arranged to regulate a control pressure which is supplied to control a load-sensing valve in a trailer brake system.