Importance

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Abstract

A door closer has a cylindrical body `A` installed in a swing door and a base plate `B` fixed to a wall `C` standing still and near the door. The body `A` has an oil-hydraulic third cylinder 3 fixed by a connecting pin 4 in a second cylinder 2, which slides in a first cylinder 1 serving as an outer casing. A piston rod 7 displaceable into and out of the third cylinder has a front end fixed to a piston 5 in this, and a rear end fixed to a piston 6 at rear end of the second cylinder. A tie rod 9 connects the second cylinder's front end to the base plate, and an airtight chamber 10 is defined between the piston 6 and the first cylinder's inner end wall. An air suction passage 12 is formed through which the chamber communicates with atmosphere, a one-way valve 11 disposed in the passage allows only suction of air into the chamber, and a thin ventilation hole 13 communicates with the airtight chamber.

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First Claim