時間：2011-03-11 23:11來源：藍天飛行翻譯 作者：admin 點擊：次
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crankshaft (reciprocating engine component). The central component of a reciprocating engine, a high-strength, alloy steel shaft with hardened and polished bearing surfaces that ride in bearings in the crankcase. Offset throws are formed on the crankshaft on which crankpins are ground and polished. Connecting rods, driven by the pistons, ride on the crankpins and change the in-and-out motion of the pistons into rotation of the crankshaft. The propeller of an airplane or the rotor system transmission of a helicopter is driven by the crankshaft. crankshaft runout (reciprocating engine dimension). The amount a crankshaft is bent. Runout is checked by supporting the crankshaft in V-blocks or rollers and mounting a precision dial indicator so its arm rides around the end of the crankshaft as it is rotated. As the shaft is turned, the dial indicator shows the amount, usually in thousandths of an inch, the shaft is bent, or the amount it is run out. crater (welding bead component). A recess, or dip, in the puddle of molten metal in the flame of a gas welding torch or in the arc used for electric welding. crazing. A form of heat damage that occurs in a transparent thermoplastic material. Crazing appears as a series of tiny, hairlike cracks in the surface of the plastic. If a material is heated nonuniformly, one side will expand more than the other, and the stresses caused by the uneven expansion produce the crazing. Crazing destroys the strength of the material and makes it difficult to see through. creep (gas turbine engine component defect). A condition of permanent elongation of a turbine blade. Creep causes the turbine blades to actually grow in length when they are acted on by high temperature and high centrifugal loading. creeper (shop tool). A flat board with low wheels on it. A mechanic can lie on a creeper while working under the fuselage or under a low wing of an airplane. crepe masking tape. A form of paper tape which is crinkled, with one side coated with a pressure-sensitive adhesive. Crepe masking tape is used to prepare a surface for painting. The crinkles allow the tape to lie flat when it is used to mask a curved line. Crescent wrench. The registered trade name for an adjustable open-end wrench. Because of its popular use, the name Crescent wrench has become accepted as the generic name for this type of wrench. A Crescent wrench has one fixed jaw and one adjustable jaw. The adjustable jaw moves in and out, parallel to the fixed jaw. The jaws form a parallel opening that is offset by about 15° from the axis of the wrench handle. crewmember (aircraft flight crew). A person aboard an aircraft for the purpose of operating the aircraft in flight. 14 CFR Part 1: “A person assigned to perform duty in an aircraft during flight time.” crimping (sheet metal fabrication procedure). Shortening a piece of sheet metal by forming small pleats or corrugations in its surface. A formed metal angle may be bent into a curve by crimping the edge of one of its legs. |
