Patent ID: 8042417

Claim:
An actuator comprising a rotatable actuator member ( 14 , 114 ) and a lock arrangement ( 28 , 128 ) operable to lock the actuator member ( 14 , 114 ) against rotation, the lock arrangement ( 28 , 128 ) comprising an axially movable lock member ( 30 , 130 , 230 a , 230 b ), the lock member being movable between a locked position in which it co-operates with a stop ( 34 , 134 ) to resist rotation of the actuator member ( 14 , 114 ), and a released position, and an actuation device ( 62 , 162 ) operable to move the lock member ( 30 , 130 , 230 a , 230 b ) towards its released position, a release spring ( 42 , 142 , 242 ) is provided which urges the lock member ( 30 , 130 , 230 a , 230 b ) towards its released position, and a lock spring ( 44 , 144 , 244 ) is provided which urges the lock member ( 30 , 130 , 230 a , 230 b ) towards its locked position, the lock spring ( 44 , 144 , 244 ) engages a movable stop or abutment ( 48 , 148 , 248 ), movable to vary the spring loading applied to the lock member ( 30 , 130 , 230 a , 230 b ), and wherein the movable abutment ( 48 , 148 , 248 ) is spring biased by a pusher spring ( 58 , 158 , 258 ).