Abstract: A gate valve actuator which can be quickly and easily refitted to manually operable holding tank gate valves on recreational vehicles to convert to remote operation. The actuator includes a housing with clamping flanges and a clamping plate which are used to clamp the actuator housing to the slide gate housing. A traveler block having a fork to engage and move the valve handle is threadably connected to a threaded drive shaft which is selectively rotated by an electric motor to move the valve handle between its open and closed positions. Limit switches terminate power to the motor when the fully open or closed positions are reached. The actuator can be easily removed to again permit manual operation.