Abstract: An actuator apparatus comprising an actuator member, an actuated element movable by actuation of said actuator member, and a marker device including a marker the position of which can be sensed in use by sensor means, said marker device being secured to said actuator member such that deformation of the actuator member during actuation to move said element causes an adjustment to the change in position of the marker.

Abstract: An actuator apparatus comprising an actuator member, an actuated element movable by actuation of said actuator member, and a marker device including a marker the position of which can be sensed in use by sensor means, said marker device being secured to said actuator member such that deformation of the actuator member during actuation to move said element causes an adjustment to the change in position of the marker.

Abstract: Thermal expansion within a gearbox causes relative motion of all of the component parts therein. For gearboxes having components made of different materials, differential thermal expansion may alter the clearances between meshing gears and give rise to increased backlash. The gearbox comprises a compensation member arranged to move one end of an axle having a first gear therein in response to changes to temperature so as maintain the first gear in substantially temperature invariant engagement with a second gear.

Abstract: An actuator lock is provided to prevent movement of an actuator until the actuator lock is released. A first member of the lock is movable in response to fluid pressure within a chamber to move from a locked position to an unlocked position allowing the actuator to move. The first member is held at the unlock position by a latching member so that the lock cannot return to the locked position. During testing of the actuator, a test member is operable to reversibly move the first member from the locked position to an unlocked and unlatched position.