词条 | bellows |
释义 | bellows mechanical device ![]() In its simplest form, a hand bellows consists of two flat boards of rectangular, circular, or pear shape, hinged at one end and connected around their edges by a wide band of flexible leather to form an airtight joint. Wire rings keep the leather from collapsing when the boards are separated suddenly and the pressure in the chamber is less than atmospheric. One of the boards has a hole in the centre, covered inside by a leather flap or valve that can open only inward. The outlet nozzle has a relatively small opening. When the boards are separated, the partial vacuum created causes the air to rush into the chamber through the valve; when the boards are brought together, the valve closes, and the air in the chamber is discharged through the open nozzle. |
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