A system for driving a wind turbine blade (46) into a feathered position during an emergency stopping process of a wind turbine rotor. The system comprises a hydraulic actuator (3) functionally connected to the blade (46) for changing the pitch of the blade (46) during movement of the hydraulic actuator (3) and an emergency accumulator (8) connected to the hydraulic actuator (3) for driving the hydraulic actuator (3) with fluid from the emergency accumulator (8). The emergency accumulator (8) comprises a resilient member for accumulating the fluid in the emergency accumulator (8) under resilient pressure or a weight member (74) comprising a weight member upon the fluid in the emergency accumulator. The resilient member (14) or weight member (74) is configured for driving the fluid out of the emergency accumulator due to the expansion or retraction of the resilient member.