汽車專業(yè)英語電子課件Unit 9

1、unit 9periodic maintenancepurpose of periodic maintenancepurpose of periodic maintenanceauto maintenance refers inspecting or testing the condition of car and servicing or replacing parts and fluids. periodic maintenance is critical to ensure the safety, reliability, drivability, comfort and longevi

2、ty of a car. an automobile is constructed from a large number of parts, which can become worn-down, weakened or corroded to lower the performance, depending on the conditions or the length of use. during periodic maintenance, a number of parts are replaced to avoid major damage or for safety reasons

3、, e.g. timing belt replacement.service intervals are decided according to the distance traveled and the period elapsed since the previous service. if the vehicle is being used under any of the following conditions, frequent maintenance will be necessary.(1) rough or extremely muddy roads, roads on w

4、hich snow has melted, extremely dusty roads.(2) vehicles used for towing a trailer, or for pulling a camper. (3) vehicles used on repeated short trips of 8 km or less at temperatures below freezing.(4) vehicles being used as police patrol cars, taxis or in door-to-door calls, which are left idling f

5、or long periods or run extended distances at low speeds (5) vehicles being driven for over 2 hours at high speeds (80% speed through the maximum speed of the vehicle).the items for servicing of the periodic maintenance and the service interval of the vehicle are stated in the maintenance schedule ch

6、art of the owners manual. the maintenance schedule is stipulated by these factors: model, age, country in which is used, or how to use (state) of the vehicle. t, r, i, a, l stand for symbols of maintenance operation. t=tighten to specified torque. r=replace or change. i=inspect and correct or replac

7、e as necessary. a=check and/or adjust as necessary. l=lubricate.the contents of the maintenancefor periodic maintenance, the technician primarily inspects the functions that are necessary for ensuring the safe operation of the vehicle. the inspection is performed as follows:(1) car wash.(2) check/re

8、place the engine oil and replace oil filters.(3) check/replace fuel filters.(4) inspect or replace windshield wipers.(5) check or refill windshield washer fluid.(6) inspect tires for pressure and wear.(7) tire balancing.(8) tire rotation.(9) wheel alignment.(10) check, clean or replace battery termi

9、nals and top up battery fluid.(11) inspect or replace brake pads.(12) check or flush brake fluid.(13) check or flush transmission fluid.(14) check or flush power steering fluid.(15) check and flush engine coolant.(16) inspect or replace spark plugs(17) inspect or replace air filter.(18) inspect or r

10、eplace timing belt and other belts.(19) lubricate locks, latches, hinges.(20) check all lights.(21) tighten chassis nuts and bolts.(22) check if rubber boots are cracked and need replacement.(23) test electronics, e.g., anti-lock braking system or abs.(24) read fault codes from the engine control un

11、it.the tools of the maintenance socket wrench setthis tool can be used for the easy removing and replacing of bolt/nut through the combination of various handles and sockets, depending on the operating conditions. this tool holds on the bolt/nut that can be removed or replaced with a socket wrench s

12、et (fig.9.2). air impact wrenchair tools utilize pressurized air, and are used for removing and replacing bolt/nut. they enable work to be completed quickly. the tool must be held with both hands when operating. simply operating the buttons releases a large torque, and may cause shaking. the positio

13、n and the shape of the torque adjustment knob and the rotation direction button vary by manufacturer. inspect air tools (fig.9.4) periodically and apply air tool oil for lubrication and rust prevention.the measuring instruments of the maintenance vernier calipercalipers can measure length, outside d

14、iameter, inside diameter and depth. the vernier caliper (fig.9.4) is an extremely precise measuring instrument; the reading error is 1/20 mm = 0.05 mm. close the jaws lightly on the object to be measured. if you are measuring something with a round cross section, make sure that the axis of the object is perpendicular to the caliper. this is necessary to ensure that you are measuring the full diameter an