时间：2011-03-11 23:13来源：蓝天飞行翻译 作者：admin 点击：次
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drive coupling (engine component). A shock-absorbing coupling used between the accessory drive in an engine and an accessory that is subject to torsional vibrations. A safety link designed to shear if the accessory should freeze, or jam, is usually incorporated as a part of a drive coupling. drive fit (mechanical fit). A tight fit between mating parts of a mechanism in which one part fits inside another. In a drive fit, the hole is smaller than the part that fits into it, and force must be used to assemble the parts. A drive fit is also called an interference fit. drive gear. The gear attached to the power source in a gear train. The drive gear meshes with and drives the driven gear. If the drive gear is smaller than the driven gear, the driven gear turns slower than the drive gear. driven gear. The gear in a gear train that meshes with and is driven by the drive gear. driver (electronic circuit). A piece of electronic equipment in a circuit that supplies input power to an output circuit or device. driver head (threaded fastener). A type of bolt or screw head that is either slotted or fitted with a recess. A driver head makes it possible to drive the fastener with some form of screwdriver, rather than with a wrench. drivescrew. A form of self-tapping screw that has no screwdriver slot nor recess in its head. Drivescrews are used to attach nameplates to an engine crankcase and to plug holes in a tubular steel structure through which preservative oil has been pumped. Drivescrews are installed by driving them in place with a hammer. drizzle (meteorology). Very small droplets of water that appear to float with the air currents while falling in an irregular path. Drizzle differs from rain, which falls in a comparatively straight path, and fog, whose droplets remain suspended in the air. drogue. Any of several types of devices used to slow or stabilize a body moving through water or air. A drogue parachute is a small parachute which can be opened behind an airplane to slow or stabilize it in flight. A drogue is also the funnel-shaped device on the end of an inflight refueling hose. The drogue stabilizes the hose and allows the aircraft being refueled to connect its probe into the fueling line. A sea anchor, which is a canvas bucket with a small opening in its bottom, is also a drogue. A sea anchor is used to stabilize and control the movement of a boat or seaplane. drone. A pilotless airplane used for target practice or for research in conditions that would be dangerous for a manned aircraft. Drones are remotely controlled by radio from a mother aircraft or from a ground station. droop (turbine engine fuel control condition). A progressive decrease in RPM with load in an engine whose speed is governed with a flyweight-type governor. As the load is increased, the pilot valve drops down to meter more fuel. The lower position of the valve decreases the compression of the speeder spring and allows the flyweights to assume an onspeed position at a lower RPM. |
