Actuator assembly

An oil or gas well actuator (1) assembly comprising a fixed member (10), an actuating member (30) being moveable axially with respect to the fixed member, with open-ended recesses containing canted coil springs (40) on e.g. the fixed member and a radially extending shoulder (30s) on the actuating member which adapted to engage a canted coil spring within a recess (20). A support member (50) is adapted to cover open ends of the recesses and moves into different axial positions with respect to the recesses to uncover open ends of different recesses in the different axial positions of the support member. Expansion of a canted coil spring (40) from an open end of a recess engages with the shoulder (30s) to restrict movement of the actuating member (30) at indexed positions. When the actuating member (30) moves relative to the support member direction, the support member (50) retains its position relative to the canted coil spring.