Patent ID: 8240223

Claim:
An actuator arrangement comprising a pair of screw actuators driven from a common motor through respective drive shafts connected to respective outputs of a differential gearbox, and a protection arrangement comprising a tie arrangement connected across the outputs of the differential gearbox and to each corresponding respective driveshaft, wherein the tie arrangement is responsive to a difference in the torques applied to the drive shafts and arranged to avoid the continued application of drive to one of the screw actuators in the event of the occurrence of a jam condition associated with that one of the screw actuators, wherein the tie arrangement is operable to resist relative rotation of the drive shafts and ensure that the screw actuators are synchronized when the difference in the torques applied thereto is less than a predetermined level, and operable to permit such relative movement in the event of a torque difference greater than the predetermined level being applied thereto to avoid the continued application of drive to the said one of the screw actuators.