Marsh Automation Pvt. Ltd. Manufactures Quarter Turn Worm Gear Operation Unit. Marsh Automation Pvt. Ltd. Is an ISO 9000 awarded company. The company manufactures Electrical Activators Motorized Valves, Pneumatic Valves, Electrical or Pneumatic Actuators. The Quarter Turn Worm Gear Operation Unit specially designed to operate valves that turn thru 90° these include, ball, butterfly, and plug valves and also the dampers. Adjustable, mechanical stoppers are provided to set the operator within ± 5% of the extreme end positions. A mechanical position indicator is provided on these units to show the valve position [Open and Shut].