| 摘要 |
A door closer having a spindle and cam arrangement for driving a cam plate longitudinally within a housing filled with oil, and dual rods connected to the cam plate at one end and to two pistons respectively at an opposite end. The pistons are reciprocal within cylinders having speed valves in flow communication to opposite sides of the pistons. Dual springs are arranged, one around each rod and compressed between the pistons and a fixed compression plate within the housing. A single adjusting screw extends from a front end of the housing to a threaded central aperture of the compression plate. Rotation of the adjusting screw sets the initial spring compression force of the return springs which influences the rate of closure of the door and the preload force of the door to the door frame.
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