The Delphi Saginaw Steering Systems innovation QUADRASTEER has a rear axle with electronic, fully steerable rear wheels. QUADRASTEER offers revolutionary improvement in the handling and maneuverability of full-size pickups, vans, and sport utilities. In low speed maneuvering, where the rear wheels steer in negative phase, opposite the front wheels, QUADRASTEER reduces the minimum steering circle of these large vehicles to the equivalent of a compact sedan. Ease of maneuvering in tight situations, such as parking garages, is improved proportionately.
At high speeds, the rear wheels steer in positive phase with the front wheels, greatly improving maneuverability and control. Freeway lane change maneuvers in particular are rendered quicker and more comfortable with QUADRASTEER. These maneuvers are accomplished with much less vehicle yaw and roll than with conventional two-wheel steering, perceptible to passengers as less upper body sway. In emergency lane change maneuvers, the reduction in yaw greatly enhances control.
A third benefit of QUADRASTEER is in trailer towing. At low speed, maneuverability of a QUADRASTEER equipped truck and conventional trailer is enhanced both forward and in reverse. At high speed, the reduced yaw of the towing truck in maneuvers reduces trailer yaw, which in turn greatly reduces the tendency of a heavy trailer to “wag” the tow vehicle.
QUADRASTEER consists of a steering wheel position sensor, a steerable rear axle, an electronic actuator, an electronic controller, and a mode switch for selecting 2-wheel steer, 4-wheel steer, and 4-wheel steer in trailer tow mode. The rear steering is “steer by wire,” with no mechanical linkage to the front steering. It is designed to return to neutral (2-wheel steering) if a part of the system should fail.
QUADRASTEER is available initially in the 2002 GMC Sierra Denali and is to appear as an option in other vehicles. It is projected to reach about a 30% penetration in vehicles of this type, although some analysts have suggested a much stronger reception from truck buyers.