Patent ID: 11084529

Abstract:
A method of brake steering in a four-wheel drive utility vehicle having a driven front axle carrying at least two front wheels, a driven rear axle carrying at least two rear wheels, a powertrain delivering torque to the front axle via a first motor and to the rear axle via a second motor, a controlled clutch arrangement operable to couple the outputs of the first and second motors to vary the distribution of delivered torque between the front and rear axles, and independently operable service brakes on each of the front and rear wheels. The method includes determining a difference in wheel velocity between front and rear wheels; comparing the difference to a threshold value and, when exceeded, automatically engaging the controlled clutch arrangement. A determination is made as to whether or not the vehicle is performing a brake steering manoeuvre and the threshold value is adjusted accordingly. Additional braking force may be applied from independently operable park brakes on the rear wheels in inverse relationship to the level of service brake force applied.