| 摘要 |
A door closer includes a casing fixedly fastened to a door leaf, a shaft turned in axle holes in the casing, a spiral spring mounted around the shaft within the casing and having one end fixed to the shaft and an opposite end fixed to the casing and adapted for returning the door leaf to the close position each time it is opened, a rack fixedly fastened to a door frame to which the door leaf is hinged, a bevel gear fixedly mounted on one end of the shaft and turned with it along a 90-degree arc toothed bar section of the rack, and a curved springy holding down plate fastened to the rack and adapted for holding down the bevel gear to keep the door leaf to be retained in an open position.
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