HICAS - Heavy Duty Actively Controlled Suspension

Acronym for Nissan for High Capacity Active-Control Suspension, an electronic dynamic attitude control system that is applied to vehicles with four-wheel steering (4WS).

The rear wheels are steered by means of an electronically controlled remote hydraulic pressure actuator: the position of the rear steering wheel is indirectly controlled by very stiff re-centering springs. The volume of the command is set by the electronic control unit, which includes the signals from the steering angle and speed sensor. Structurally, the system consists of a solenoid valve, which is a hydraulic pressure distribution spool with two solenoids, one on each side, to control movements in both directions. The rear drive cylinder receives pressurized fluid from the HICAS valve and drives the steering of the wheels.