Steven Levy Enterprises buys and sells new, unused, and used industrial surplus valve actuators and gear operators. Browse our inventory of valve actuators and gear operators available for purchase. A valve actuator is a mechanical device that uses a power source to operate a valve. This power source can be electric, pneumatic (compressed air), or hydraulic (the flow of oil). Gear-operated valves regulate the flow of liquid or gas. This involves the operation of a wheel moving a disc which holds or releases the liquid or gas through a system. Gear operated valves require manual operation. Tell us what surplus valve actuators and gear operators you have for sale or call us at 713-910-4337.