A very special version of the hydraulic power steering system used in most passenger cars is used in the EV1. Its hydraulic pump is driven by a small motor. The electric motor is used for a couple of reasons. First, because the drive motor is off when the car is stopped, and cannot drive the pump, just when you most need it for parking assist. Second, it is also able to be programmed to provide just the necessary amount of assist as the vehicle’s speed and your steering needs change. For example, while going straight, very little assist is needed and the pump is in an energy saving mode, but it goes immediately to work when the steering wheel is turned.
Copyright 2001 General Motors Corporation. All rights reserved.