Electrically-controlled actuators

An electrically-controlled force-exerting actuator comprising a force-applying power spring arranged to exert a variable force on an output member, a force-applying control spring arranged with respect to the power spring such that a variable force exerted by the control spring is detracted from the force exerted by the power spring to determine the residual variable force exerted on the output member by the power spring, an electric motor operable to vary in a graduated manner the detractive force exerted by the control spring, and an adjustable stop variation of the position of which variably determines the minimum force exertable by the control spring.