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1、附录 英文文献翻译Drive axle/differentialAll vehicles have some type of drive axle/differential assembly incorporated into the driveline. Whether it is front, rear or four wheel drive, differentials are necessary for the smooth application of engine power to the road.Powerflow The drive axle must transmit po
2、wer through a 90 angle. The flow of power in conventional front engine/rear wheel drive vehicles moves from the engine to the drive axle in approximately a straight line. However, at the drive axle, the power must be turned at right angles (from the line of the driveshaft) and directed to the drive
3、wheels.This is accomplished by a pinion drive gear, which turns a circular ring gear. The ring gear is attached to a differential housing, containing a set of smaller gears that are splined to the inner end of each axle shaft. As the housing is rotated, the internal differential gears turn the axle
4、shafts, which are also attached to the drive wheels.Figure 11 Component parts of a typical driven axle assembly. Differential operationThe differential is an arrangement of gears with two functions: to permit the rear wheels to turn at different speeds when cornering and to divide the power flow bet
5、ween both rear wheels.The accompanying illustration has been provided to help understand how this occurs. The drive pinion, which is turned by the driveshaft, turns the ring gear (1).The ring gear, which is attached to the differential case, turns the case (2).The pinion shaft, located in a bore in
6、the differential case, is at right angles to the axle shafts and turns with the case (3).The differential pinion (drive) gears are mounted on the pinion shaft and rotate with the shaft (4).Differential side gears (driven gears) are meshed with the pinion gears and turn with the differential housing
7、and ring gear as a unit (5).The side gears are splined to the inner ends of the axle shafts and rotate the shafts as the housing turns (6).When both wheels have equal traction, the pinion gears do not rotate on the pinion shaft, since the input force of the pinion gears is divided equally between th
8、e two side gears (7).When it is necessary to turn a corner, the differential gearing becomes effective and allows the axle shafts to rotate at different speeds (8).As the inner wheel slows down, the side gear splined to the inner wheel axle shaft also slows. The pinion gears act as balancing levers
9、by maintaining equal tooth loads to both gears, while allowing unequal speeds of rotation at the axle shafts. If the vehicle speed remains constant, and the inner wheel slows down to 90 percent of vehicle speed, the outer wheel will speed up to 110 percent. However, because this system is known as a
10、n open differential, if one wheel should become stuck (as in mud or snow), all of the engine power can be transferred to only one wheel.Figure 12 Overview of differential gear operating principles. Limited-slip and locking differential operation Limited-slip and locking differentials provide the dri
11、ving force to the wheel with the best traction before the other wheel begins to spin. This is accomplished through clutch plates, cones or locking pawls.The clutch plates or cones are located between the side gears and the inner walls of the differential case. When they are squeezed together through
12、 spring tension and outward force from the side gears, three reactions occur. Resistance on the side gears causes more torque to be exerted on the clutch packs or clutch cones. Rapid one wheel spin cannot occur, because the side gear is forced to turn at the same speed as the case. So most important
13、ly, with the side gear and the differential case turning at the same speed, the other wheel is forced to rotate in the same direction and at the same speed as the differential case. Thus, driving force is applied to the wheel with the better traction.Locking differentials work nearly the same as the
14、 clutch and cone type of limited slip, except that when tire speed differential occurs, the unit will physically lock both axles together and spin them as if they were a solid shaft.Figure 13 Limited-slip differentials transmit power through the clutches or cones to drive the wheel having the best t
15、raction.Identifying a limited-slip drive axleMetal tags are normally attached to the axle assembly at the filler plug or to a bolt on the cover. During the life of the vehicle, these tags can become lost and other means must be used to identify the drive axle.To determine whether a vehicle has a lim
16、ited-slip or a conventional drive axle by tire movement, raise the rear wheels off the ground. Place the transmission in PARK (automatic) or LOW (manual), and attempt to turn a drive wheel by hand. If the drive axle is a limited-slip type, it will be very difficult (or impossible) to turn the wheel. If the drive axle is the conventional (open) type, the wheel will turn easily, and the opposing wheel will rotate in the reverse direction.
