Overhead door with a plunger assembly having a wear indicator and improved panel construction

摘要

An overhead door having two tracks each of which is designed to be mounted on the side of an opening in a building. Each track has a script-v shape in cross-section, and a groove or channel that runs along its longitudinal axis. One or more panels are positioned between the tracks and coupled to each other. Each panel has a multiple-layer design that provides superior insulation. At least two plungers are positioned on each panel and each plunger has a first end which is biased in a first position. In the first position, the first end of the plunger rides within the channel of the track. The plungers are designed with a low-friction tip that wears away after repeatedly traveling in the channel of the track. The plungers may be designed to release from the track when the panel on which they are mounted is impacted, to rotate in whole or in part as they travel in a channel of a track, or both.