A braking system of a work machine includes a pressurized fluid supply, a base valve fluidly coupled to the supply, a proportional control valve fluidly coupled to the supply, and a fluid output configured to be fluidly coupled to a braking system of a trailer. A first fluid path is selectively fluidly coupling the supply to the fluid output via the base valve, and a second fluid path is selectively fluidly coupling the supply to the fluid output via the proportional control valve. The base valve includes a predefined fixed gain and the proportional control valve includes an adjustable ratio.