時(shí)間：2011-03-11 23:11來(lái)源：藍(lán)天飛行翻譯 作者：admin 點(diǎn)擊：次
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balanced field length. The runway length in which the takeoff distance is the same as the number of feet required to accelerate an airplane to a go/no-go speed, decide to abort the takeoff, and come to a complete stop. balanced pressure torch (welding torch). A welding torch in which the oxygen and fuel gas are supplied at the same pressure. Each gas has its own valve to control the amount delivered to the tip. balanced transmission line (radio-frequency electrical energy transmission). A transmission line having equal impedance between each conductor and ground, and between each conductor and any other electronic circuit to which it is connected. ball bearing. A popular type of antifriction bearing used in many types of machinery. The outer race, consisting of a grooved hardened steel ring, is mounted in the stationary housing. And an inner race with a matching groove is mounted on the rotating shaft. Polished, hardened steel balls ride in the grooves and support the shaft. The balls are kept spaced evenly in the grooves by a thin sheet-metal bearing retainer. Ball bearings can be designed to support thrust loads as well as radial loads. ball check valve (fluid power system component). A type of flow control valve used in a fluid power system to allow fluid to flow in one direction but not in the other. A ball check valve contains a spring-loaded ball that seats in one side of the valve. The ball is forced tightly against its seat by fluid entering the valve from the end containing the spring, and the fluid cannot flow through the valve. Pressure on the side of the valve containing the ball forces the ball off its seat and fluid flows through the valve. Fluid flowing through the valve is opposed only by the force of the spring. ball joint (exhaust system). A flexible expansion joint used in an aircraft engine exhaust system to allow relative movement between the parts as heat causes them to expand and contract. |
