A fluid-operated actuator assembly has a valve with an inlet for connection to a pressurized fluid source, a bi-stable electromagnetic device for operating the valve, which has a first state closing the valve and a second state opening the valve, a hydraulic actuator, and an electronic control circuit. The hydraulic actuator has an actuating member in a housing, the housing having a chamber on one side of the actuating member to which an outlet of the valve is connected for receiving fluid from the fluid source when the valve is opened, the actuating member for operation of the hydraulic actuator. The control circuit momentarily energizes the bi-stable electromagnetic device to the hydraulic actuator from the second state, back to the first state, to terminate operation of the hydraulic actuator.