A steering apparatus (10) for turning steerable wheels of a vehicle having first and second sets (14 and 16) of steerable wheels comprises a first steering gear (22) actuatable, in response to rotation of a handwheel (110), to effect turning of the first set (14) of steerable wheels. The steering apparatus (10) also comprises second and third steering gears (24 and 26), each of which is independently actuatable to effect turning of the second set (16) of steerable wheels and thereby providing redundancy for turning of the second set (16) of steerable wheels. A sensor (112) senses a steering position of the first set (14) of steerable wheels and provides a steering signal indicative of the sensed steering position. A controller (114) receives the steering signal and, in response to the steering signal, controls actuation of the second and third steering gears (24 and 26).