Closedbolt

Closedbolt is a term used in mechanical engineering to describe a locking bolt mechanism designed to hold a moving part in a fully closed or locked position. The concept contrasts with open-bolt configurations, in which the bolt rests in an extended or retracted state depending on the design. Closedbolt assemblies are favored in systems where maintaining a sealed or secured state is critical, such as valves, actuators, safety enclosures, and certain firearm mechanisms.

Design and components commonly include a cylindrical bolt housing, a sliding or rotating bolt, an actuator (manual lever, solenoid, pneumatic or hydraulic cylinder), and a retention or spring system. Guides, bushings, and seals are used to ensure alignment, minimize wear, and prevent leakage. A latching element or detent may provide a clearly defined locked position and resistance to unintended retraction.

Operation typically involves an actuation event that moves the bolt from its locked position to a safe or open position, followed by re-engagement to restore the closed state when the actuation force is removed. Some closedbolt designs incorporate fail-safe behavior, wherein loss of power or pressure causes the bolt to move to the closed position for safety.

Variants of closedbolt mechanisms differ in actuation method, lockholding force, and fail-safe characteristics. They are chosen for applications requiring reliable closure under vibration, pressure, or harsh environments, as well as for systems where a consistent sealed interface is essential.

See also: latch, bolt mechanism, valve actuation, locking device.