A linear motion actuator is disclosed in which an actuator shaft is held in a ready position by a latching ring. A spring is attached to the actuator shaft to exert a biasing force on the actuator shaft biasing it toward its actuated position. The latching ring receives one end of the actuator shaft and has locking elements that hold the actuator shaft in the ready position. A latching ring is rotated to selectively release the locking element. A shape memory alloy link extends partially around the latching ring and is secured to the latching ring. The link is shortened when current is applied to the link causing the link to rotate and release the locking element.