Chain Hoist

A chain hoist is a hand-operated mechanical device mounted to the barrel assembly of a commercial rolling steel door. An operator pulls a loop of hand chain that feeds through a sprocket attached to the barrel. Each pull rotates the barrel a small increment, winding the curtain upward. Releasing the chain holds the door at that height through an internal brake or ratchet.

Chain hoists are used on rolling steel doors in warehouses, loading docks, and industrial buildings where a powered operator is not installed or where a backup manual method is required. They are common on doors that are opened infrequently, such as fire exits or secondary service doors.

A typical commercial service door measuring 12 feet wide by 12 feet tall may have a curtain and hardware assembly weighing 300-500 pounds. The tension wheel on the barrel sets the spring counterbalance that offsets most of that weight, so the force needed to pull the chain is manageable by one person.

The chain hoist mounts to one side of the barrel bracket at head height. On fire-rated rolling doors, the chain hoist must allow the door to close freely when the fusible link releases, so it incorporates a slip mechanism that does not lock the curtain open.

Compare the chain hoist to a powered operator: a motor-driven rolling door uses an electric motor geared to the barrel in place of the manual sprocket. The chain hoist remains the fallback method during power outages on motorized doors that include a manual override feature.

The rolling door guide channels the curtain edges on each side as it rises and falls, keeping the curtain aligned regardless of whether it is being driven by motor or chain.