Hydraulic Servo-Steering Device and Method for Controlling a Pump Drive Motor

Abstract

A hydraulic servo-steering device includes a pump and a pump drive motor. At least one defined high power stage (C) and one defined low power stage (B) are provided in which the motor is selectively operated. Moreover, a defined additional power stage (A) is provided for the motor, in which the speed of the motor is reduced with respect to the low power stage (B). According to a method for controlling the pump drive motor of the hydraulic servo-steering device, the motor is operated in the additional power stage (A) under certain conditions which rule out an impairment to driving safety.

Dependencies are inferred from the claim text.