作者：宋红英
页数：199
出版社：机械工业出版社
出版日期：2009
ISBN：9787111275824
电子书格式：pdf/epub/txt
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插图：Camshaft’ s function is to open the engine valves posi-tively and timely, in a definite sequence, and to control theirclosing against the return action of the valve springs. Theshaft is made integral with its cams and bearing journals.Each cam controls a single valve, either intake or exhaust. Insome automobile engines, the camshaft is made integral withfuel pump eccentric wheel and oil pump drive gear. Thecamshaft bearings are lubricated with oil supplied under pres-sure from the main gallery in the cylinder block. The tappets serve to transmit the force from the camshaftto the push rods. The tappets are small cylindrical bores re-ceiving the push rods. They are made of cast iron or steeland located in the guides, which may be made integral withthe cylinder block or removable as in the engine. When theengines operate, the tappets continuously rotate about theiraxes for uniform wear. The rotation is ensured by a convexsurface of their bottoms and a slanted surface of the cams. The push rods transmit the force from the tappets to the rocker. They usually have small con-vex balls inserted on each of their ends. These convex bails fit into the tappet and rocker arm toallow proper movement. Overhead camshafts do not need the push rod. Rocker arms are designed to change the direction of the cam lifting force and provide a cer-tain mechanical advantage during valve lifting. The purpose of the mechanical advantage is toopen the valve more than the actual lift of the camshaft lobe, which can be done by changing thedistance from the pivot point to the end of the rocker ann. There is the valve clearance betweenthe rocker contact pad and the valve stem tip, so that the valve will be tightly pressed against itsseat when hot. The clearance can be adjusted by adjusting screw of the rocker arm. Each cylinder of a four-stroke-cycle diesel or gasoline engine is commonly equipped with anintake valve a
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《汽车专业英语(第2版)》共八个单元。第一、二、三、四单元以汽车构造为主，介绍发动机、底盘及电气设备等内容；第五单元为汽车销售和售后服务用语，主要介绍客户接待、车款推介、价格商谈、维修接待等常用英语；第六单元为实用会话，模拟真实的职场情境；第七单元为常见汽车标识，主要介绍汽车标牌及VIN代码的含义；第八单元为OBD—Ⅱ故障码的中英文对照。《汽车专业英语(第2版)》内容安排合理、条理清晰，符合高职教育要求和岗位工作需要，适合高等职业技术院校汽车专业英语教学使用，也可作为相关行业岗位培训或自学用书，同时可供汽车维修人员学习参考。
