The invention generally relates to an improvement of conventional Hydraulically Power Assisted Steering system (HPAS-system) arranged to supply a steering assist force to the steering assembly of a vehicle as a response to a torque applied by a driver to a steering wheel 120. In such known HPAS-systems the input torque from the driver always results in a corresponding assist force. The invention provides a valve 300 that can be actuated to dynamically alter the steering assist force produced by the HPAS-system. This makes it possible to dynamically adjust the assist force so that an appropriate force may be delivered to fit the specific driving scenario. <IMAGE>
