This enhanced maneuverability at low speeds was instantly obvious during some handling exercises set up by Delphi on a parking lot surface. What would have been hard or maybe even impossible with the GMC Sierra 4x4 pickup in its normal configuration was simple when QuadraSteer was activated.QuadraSteer has four main components: a front-wheel position sensor, a steerable solid hypoid rear axle, an electric motor-driven actuator, and a control unit.
"Handwheel position and vehicle speed sensors continuously report data to the control unit," Tosch explains, "which in turn determines the appropriate angle of the rear wheels. Algorithms are then used to determine the correct phase of operation." The system operates in three principal phases: negative, neutral, and positive.
Tosch says, "At lower speeds, the rear wheels turn in the opposite direction of the front wheels. This is the negative phase. At moderate speeds, the rear wheels remain straight or neutral. At higher speeds, the rear wheels are in the positive phase, turning in the same direction as the front wheels."
Drivers of full-size vehicles who pull trailers will find Quadrasteer particularly interesting, Tosch maintains. "During low-speed, negative-phase towing maneuvers, the trailer follows the true vehicle path much more closely than with two-wheel steering This makes driving in city traffic with a trailer much easier, as well as low-speed maneuvering such as backing into a boat launch or parking a camper at a campsite."