时间:2011-03-11 23:18来源:蓝天飞行翻译 作者:航空 点击:次
polyphase alternating current. Alternating current electricity produced by more than one set of generator windings. The most commonly used polyphase electricity has three phases. polyphase electric motor. An induction motor designed to operate on two-phase or three-phase alternating current. polyurethane enamel. A two-part, chemically cured, finishing material that contains a high percentage of solids. Polyurethane enamel requires a long time to flow out, and this long flowing-out time gives the finish a “wet” look. Polyurethane enamel is highly resistant to mechanical abrasion and chemical action. polyvinyl chloride (thermoplastic resin). A thermoplastic resin used to make transparent tubing for insulating electrical wires. Polyvinyl chloride (PVC) tubing is used for carrying low-pressure air to aircraft instruments. pontoon (aircraft landing gear component). A float that can be attached to a land airplane to allow it to operate from water. Two pontoons are often installed on a land plane to convert it into a float plane. poppet valve (reciprocating engine component). A T-shaped valve with a circular head. Poppet valves are used to cover the intake and exhaust openings in the cylinder head of a reciprocating engine. The valves are held closed with one or more coil springs and are opened by a cam lobe or rocker arm pushing on the end of their stem. porcelain. A high-grade, translucent ceramic material having a hard, glazed finish. Porcelain is used for dishes, vases, and high-strength electrical insulators. It was used as the insulator in some early aircraft spark plugs. |