Braking in electronic braking systems

An electronic braking system for a vehicle having at least front and rear axles and having foundation brakes and a vehicle retarder which includes a variable retarder braking torque separate from said foundation brakes, wherein an electrical braking demand signal is generated from a single brake pedal and wherein said retarder is operably adjusted as displacement of said pedal is increased from zero up to a partial point in a range of movement of the pedal which is calculated to give a substantially maximum retarder power based upon total mass of the vehicle, such that for a fully laden condition of said vehicle said partial point occurs at low pedal deflection and, in an unladen condition of said vehicle, said point occurs at a higher pedal deflection, and in both the fully laden and unladen conditions, pushing of said pedal beyond said calculated partial point causes foundation braking to be commenced to supplement said retarder torque.