机械工程专业英语教程第2版lesson6.ppt

Lesson 6 Belts, Clutches, Brakes, and Chains,Terminology Text tour,机械工程专业英语教程,1,2019/7/8,Clutch Any of various devices for engaging and disengaging two working parts of a shaft or of a shaft and a driving mechanism 离合器：一种使一根轴的两个工作部分或一根轴与机械驱动装置处于相接合或分离状态的装置 Friction 1. Friction is the resistance to motion of two moving objects or surfaces over each other 摩擦：两个相互接触的物体当有相互运动或相互运动趋势时，在接触面产生的阻碍运动的作用。 2. A force that resists the relative motion or tendency to such motion of two bodies in contact 摩擦力：一种阻碍两个相接触物体之间产生相对位置移动的力。,Terminology,机械工程专业英语教程,2,2019/7/8,Chain A connected, flexible series of links, typically of metal, used especially for holding objects together or restraining or for transmitting mechanical power. 链，链条：一系列相连的，可折叠弯曲的环节，通常为金属，用来将物体联结到一起或限定物体的位置或用来传送机械能。,机械工程专业英语教程,3,2019/7/8,Timing belt 同步带,机械工程专业英语教程,4,2019/7/8,Text tour The rayon and rubber V-belt is widely used for power transmission.1 Such belts are made in two series: the standard V-belt and the high-capacity V-belt. Other types of belts are available for power transmission purposes. The teeth of so-called timing belt will keep shafts completely synchronized.2 1. power transmission 意为“动力传送，动力传动装置”。全句可译为： 人造纤维和橡胶V带被广泛用来进行动力传送。 2. timing belt 意为“同步带”。全句可译为： 同步带上的齿可以使轴与轴之间实现完全同步。,机械工程专业英语教程,5,2019/7/8,A clutch is a device for quickly and easily connecting or disconnecting a rotatable shaft and a rotating coaxial shaft.3 3. rotatable shaft 意为“可以转动的轴，从动轴”；rotating shaft 意为“转动的轴，主动轴”。全句可译为： 离合器是一个用来使从动轴与位于同一轴线上的主动轴进行快速和顺利的联接或脱开的装置。,机械工程专业英语教程,6,2019/7/8,The rotor (rotating member) in an electric motor has rotational inertia, and a torque is required to bring it up to speed when the motor is started. If the motor shaft is rigidly connected to a load with a large rotational inertia, and the motor is started suddenly by closing a switch, the motor may not have sufficient torque capacity to bring the motor shaft up to speed before the windings in the motor are burned out by the excessive current demands.4 4. rotational inertia 意为“转动惯量”。全句可译为： 如果电动机的轴与具有很大转动惯量的负载刚性地联接在一起，当合上开关使电动机突然启动时，有可能在电动机没有来得及产生足够的扭矩，使电动机的轴达到应有的转速之前，电动机内的线圈就会因为过大的电流而被烧毁。,机械工程专业英语教程,7,2019/7/8,A brake is similar to a clutch except that one of the shafts is replaced by a fixed member. The basic function of a brake is to absorb energy (i.e., to convert kinetic and potential energy into friction heat)5 and to dissipate the resulting heat without developing destructively high temperatures. 5. kinetic and potential energy 意为“动能与势能”。全句可译 为： 将动能与势能转化为摩擦热。,机械工程专业英语教程,8,2019/7/8,The rate at which heat is generated on a unit area of friction interface is equal to the product of the normal pressure, coefficient of friction, and rubbing velocity.6 6. coefficient of friction 意为“摩擦系数”。全句可译为： 在摩擦面之间单位面积上所产生热的速率等于正压力，摩擦系数和摩擦速度三者的乘积。,机械工程专业英语教程,9,2019/7/8,Chain drives combine some of the more advantageous features of belt and gear drives. Chains provided almost any speed ratio for any practical shaft separation distance. Their chief advantage over gears is that chains can be used with arbitrary center distances. Compared with belts, chains offer the advantage of positive (no slip) drive and therefore greater power capacity.7 7. positive (no slip) drive 意为“强制（无滑动）传动”。全句可 译为： 与带传动相比，链传动的优点是强制（无滑动）传动，因此具有更大的传递动力的能力。,机械工程专业英语教程,2019/7/8,10,Chains are available in a range of accuracies extending from precision to nonprecision. Nonprecision chains are low in cost and intended primarily for noncritical drives of less than 40-kW power ratings, precision c