Abstract: An electrically-operable actuator 10, for use in locking and unlocking a latch mechanism in a motor vehicle by the selective operation of a switchable direct current electrical supply to said actuator, comprises a housing 12, 14 enclosing a reversible direct current electric motor 16 adapted to be coupled to said electrical supply, a reduction gear train, a reciprocable member 96 movable between two predefined limits and adapted at one end to be coupled with a locking lever of said latch mechanism, and a rotary, load-sensitive releasable coupling 64 provided between said reversible electric motor 16 and said reciprocable member 96, the actuator including a releasably-engagable locking lever 132 which is operable to lock said reciprocable member 96 against any movement relative to said housing 12, 14, said locking lever 132 being applied, when the actuator 10 is coupled to said switchable electrical supply and after one of said predetermined limits has been reached, by the operation of a switch means in said s