机械工程专业英语第二版必考翻译(完整版)(4)

modern industry. But whatever their derivation or properties, the purpose of lubricants is to replace dry friction with either thin-film or fluid-film friction, depending on the load, speed, or intermittent action of the moving parts. Thin-film lubrication, in which there is some contact between the moving parts, usually is specified where heavy loads are a factor. (Lubrication) （P76）

润滑剂在粘度、比重、蒸汽压、沸点和其他特性广泛不同，润滑剂为现代工业的渐长的各种需求提供广泛的选择。但无论它们的来源和特性是什么，润滑剂的目的是按移动部件的载荷、速度或间歇运动，用薄膜或流体膜摩擦取代干摩擦。薄膜润滑是指移动部件之间有部分接触，通常特指的重载荷是一个影响因素。

21. To keep the parts separated, it is necessary that the pressure within the lubricating film balances the load on the sliding surfaces. If the lubricating film’s pressure is supplied by an external source, the system is said to be lubricated hydrostatically.If the pressure between the surface is generated as a result of the shape and motion of the surfaces themselves, however, the system is hydrodynamically lubricated. This second type of lubrication depends upon the viscous properties of the lubricants. (Lubrication) （P77）

要保证零件相互分离，必须是润滑油膜内的压力与滑动表面的载荷平衡。如果润滑油膜的压力是由外部源提供，则系统被称为流体静压润滑。 如果表面之间的压力是由表面形状和表面运动而形成的结果，然而这系统被称为流体动压润滑。第二种润滑方法取决于润滑剂的粘性。

22. A condition that lies between unlubricated sliding and fluid-film lubrication is referred to as boundary lubrication, also defined as that condition of lubrication in which the friction between surfaces is determined by the properties of the surfaces and properties of the lubricant other than viscosity. Boundary lubrication encompasses a significant portion of lubrication phenomena and commonly occurs during the starting and stopping of machines. (Lubrication) （P77） 润滑状态介于干摩擦与油膜润滑之间的被称为边界润滑，其润滑状态也被定义为表面之间的的摩擦是由表面的特性、润滑油粘度之外的其它特性所决定的。边界润滑在润滑现象中占据相当大的比重，并且通常发生在机器启动和制动阶段。

23. Shops often overlook vibration issues when installing machine tools or equipment. However, planning for vibration control, optimally before constructing a new facility or during redesign of an existing one, can save shops a lot of money in the long run. That’s because isolating machines and processes from unwanted vibration reduces future problems such as bad part-surface finished, parts out of tolerance, and even physiological damage to shop personnel. (Isolating Unwanted Vibration)（P93）

车间常在安装机床或设备时忽视震动问题。然而，最好在构造一个新设施或从新在设计一个现有的设施之前理想规划震动控制，这可从长远利益上为车间节省许多费用。这因为将机器和加工从有害震动中隔离可减少未来的问题，如避免低的零件表面精度，零件超公差，甚至工作人员的生理损害。

24. Some equipment manufacturers provide allowable-vibration specifications for their machines, but most don’t, which makes choosing an isolator system difficult. The key is knowing the amplitudes of vibration frequencies that harm machinery. Fabreeka reports this is where savvy companies call in a consultant or company specializing in vibration protection. (Isolating Unwanted Vibration) （P95）

部分设备制造商给机器提供震动许用指标，但多数不提供，这使得选择隔离系统困难，关键是了解损害机械的震动频率的幅值。 Fabreeka报告说聪明点的公司聘请了专业做震动防护的顾问或公司。

25. Such specialists measure vibration with highly accurate instrumentation such as real-time signal analyzers. These devices capture raw data, without bias, for post-processing and quantify amplitude and frequency of vibration. With this data, the specialist recommends the best isolation solution. Engineers then conduct acceptance test measurements after installation to verify amplitudes and the resultant transmitted vibration. (Isolating Unwanted Vibration) （P95） 这类专家用高精准设备检测震动，如实时信号分析仪。这些设备不是真地捕获原始数据， 为