A TRAILER BRAKING SYSTEM

A trailer braking system including:a supply line (44) for connection to a continuous source of pressurised fluid;a trailer reservoir (40) for storing a volume of pressurised fluid;a spring brake, which has an apply position and a release position, and the spring brake moves to the release position when pressurised fluid is provided at or above a threshold;a spring brake control valve (10), which controls the flow of fluid to the spring brake;an immobiliser (80) having a brake release position and an immobilise position, which control the flow of pressurised fluid to the spring brake control valve (10),a temporary override valve (200) having an override position and an inactive position, and being operable to move between positions independently of the pressure in the supply line (44); wherein when the temporary override valve (200) is in the override position, the immobiliser (80) remains in the immobilise position and the spring brake remains in the apply position when the supply line (44) is unpressured and, the immobiliser (80) is moved to its brake release position and the supply line (44) is connected to the spring brake control valve (10) automatically when the supply line (44) is connected to a source of fluid, such that the spring brake is moved to the release position.