The Small Metal Box That Controls A Heavy Door
A commercial door can weigh hundreds of pounds, yet a small metal unit above it guides the door back to its frame without allowing it to slam. That unit is a hydraulic door closer. The closer combines a spring, piston, gears, oil, valves, and an external arm. These parts turn the energy used to open the door into a controlled closing movement that can support security, fire protection, accessibility, and everyday convenience.