Product Description Description   HDM De-clutchable wormgear offers simple and reliable manual positioning of the valves, dampers and other quarter-turn devices when overriding existing pneumatic, electric or hydraulic quarter-turn actuators. All unit are suitable for both indoor and outdoor installation. The modular design is to provide the most efficient and effective solution to a full … Continue reading China Professional Hdm Series De-Clutchable Worm Gear Box Manual Override Worm Gearbox differential gearbox