1、 附 录 B 一、英文原材料 DRIVE AXLES Learning Objective: Identify the parts of the rear drive axle and front drive axle. List the function of the rear axle. Compare the different types of axles. Describe the procedures for replacing axle bearings and seals. Axles are classified as either LIVE or DEAD. The liv
2、e axle is used to transmit power. The dead axle only serves as a support for part of the vehicle while providing a mounting for the wheel assembly. Many commercial trucks and truck-tractors have dead axles on the front, whereas practically all passenger vehicles use independent front-wheel suspensio
3、ns and have no front axles. The shaft in a live axle assembly may or may not actually support part of the weight of a vehicle, but it does drive the wheels connected to it. A live axle is involved with steering when it is a front drive axle. Some live rear axles are also designed to steer. The rear
4、axle of conventional passenger vehicles is a live axle, while in a four-wheel drive vehicle both front and rear axles are live. In some six-wheel vehicles, all three axles are live axles. AXLE HOUSING :The axle housing may be of the one-piece or split (banjo) type construction. The former, known as
5、the banjo type because of its appearance, is far more common (fig. 5-22). Notice that openings, both front and rear, are provided in the center housing. The front opening is closed by the differential carrier, while the rear is closed by a spherical cover plate. Since the assembly must carry the wei
6、ght of the vehicle, the axle housing in heavy trucks and tractors is a heavy cast unit. In light-duty trucks it may be a combination of cast and steel tube； in general, the center or differential and final drive case is a cast and machined unit, whereas the axle housings themselves may be welded or
7、extruded steel tubing. Items, such as brake backing plates, mounting flanges, spring mounting plates, and accessory units, may be riveted, welded, or cast into the axle housing. Inspection covers are often provided through which the internal parts can be inspected, removed, andinstalled. Lubricant f
8、iller plugs are usuallyincorporated in the housing inspection cover.To prevent pressure buildup when the axlebecomes warm, a breather vent or valve is providedatop the housing. Without this valve, the resultingpressure could force the axle lubricant past the rearwheel oil seals and damage the brake
9、linings. Thevalve is constructed so air may pass in or out of the axlehousing； however, dirt and moisture are kept out. REAR DRIVE AXLE: The rear drive axle connects the differential sidegears to the drive wheels. The axle may or may notsupport the weight of the vehicle. Rear axles arenormally induc
10、tion hardened for increased strength. There are several types of rear axle designs:semifloating, three-quarter floating, and full floating. However the semi- and full-floating types are the mostcommon. Most automobiles use the semifloating type,whereas four-wheel drive vehicles and trucks use fullfl
11、oating axles. Semifloating Axle: The semifloating axle is used in passenger vehiclesand light-trucks. In vehicles equipped with this type ofaxle, the shaft, as well as the housing, supports theweight of the vehicle. The inner end of the axle iscarried by the side gears in the differential housing.Th
12、is relieves the axle hafts of the weight of thedifferential and the stresses caused by its operation thatare taken by the axle housing. The inner ends of theaxle transmit only turning effort, or torque, and are notacted upon by any other force.The outer end is carried by a bearing locatedbetween the
13、 shaft and the housing. A tapered roller ofball-type bearing transfers the load from the shaft tothe housing. The axle shafts take the stresses caused byturning, skidding, or wobbling of the wheels.The axle shafts (fig. 5-23) are flanged or tapered onthe ends. When the tapered axle is used, the brak
14、e drumand hub are pressed onto the shafts, using keys toprevent the assemblies from turning on the shafts. Insome cases, the outer ends of the shafts may haveserrations or splines to correspond with those on thedrum and hub assembly. Should the axle break withthis type of axle assembly, the wheel ca
15、n separate fromthe vehicle. Full-Floating Axle:The full-floating axle (fig. 5-24) is used in manyheavy-duty trucks. The drive wheel is carried on theouter end of the axle housing by a pair of tapered rollerbearings. The bearings are located outside the axlehousing. In this way, the axle housings take the fullweight of the vehicle and absorb all stresses or endthrust caused by turning, skidding, and pulling. Onlythe axle shaft transmits torque from the differential.
