1、 附 录 B 一、英文原材料 Drive axle All-terrain vehicle needs frequently goes in bad road and in the roadless situation, particularly the military automobiles travel condition is worse, this requests to increase the automobile driving gears number, therefore, all-terrain vehicle uses the multiple spindle actu
2、ation. For example, if front-wheel drives automobile two front wheels will both fall into the ditch (this kind of situation to meet frequently on bad road), that automobile will be unable engines power produces through the wheel and the ground friction the driving influence to continue to go forward
3、. But if the this vehicles four wheels can have driving influence, that but also two have not fallen into the ditch the wheel to be able the normal work, causes the automobile to continue to go. Function, on multiple spindle actuation automobile, to output the power distribution is equipped with the
4、 transfer case for various driving axles. The transfer case is equipped with the high low gear generally, by further expands when the difficult area goes the transmission when gear number. the transfer cases function is the power distribution which outputs the transmission gearbox to various driving
5、 axles, and further increases the torque. The transfer case is also a gear drive system, it fixes alone on the frame, its input axis and transmission gearboxs output shaft with the rotary transmission device connection, transfer cases output shaft has certain, passes through the rotary transmission
6、device and various driving axles separately is connected. majority transfer cases, because must play the reduction of speed to increase the moment the role, but is bigger than gear boxs load, therefore in transfer cases Chang Nie the gear is a helical gear, the bearing also uses the circular cone ro
7、ller bearings supporting. Drive shafts- or propeller shafts, as they are sometimes called-have one basic function. transferring power or torque from one drive line component to another in a smooth, continuous fashion. In a heavy-duty truck, that means transmitting engine torque from the output shaft
8、 of the transmission to a rear axle or to an auxiliary transmission. Drive shafts are also used to connect forward and rear axles on 4 X 6 tractors. In most cases, a drive shaft must transfer torque at an angle to the centerlines of the drive line components it is fastened to. Be- cause the rear axl
9、e is not connected to the rigid rails of the truck frame but is mounted to the rear suspension system, the drive shaft must also be able to change angles as the rear suspension jounces and rebounds. The drive shaft must also be able to change in length while transmitting torque. As the rear axle rea
10、cts to road surface changes, torque reactions and braking forces, it tends to rotate for-ward or backward, requiring a corresponding change in the length of the drive shaft. In order to transmit engine torque to the rear axles, the drive shaft must be durable and strong. An engine producing 1 000 po
11、und-feet of torque, when multiplied by a 12 to t gear ration in the transmission, will deliver 12 000 pound-feet breakaway torque to the drive shaft. The shaft must be strong enough to deliver this twisting force to a loaded axle without deforming or cracking under the strain. Drive shafts are const
12、ructed of high-strength steel tubing to provide maximum strength with minimum weight. The diameter of the shaft and wall thickness of the tubing is determined by several factors maximum torque and vehicle payload, type of operation, road conditions, and the brake torque that might be encountered. On
13、e-piece ,two-piece ,and three-piece drive shafts are used, depending on the length of the drive line. Each end of the drive shaft has a yoke used to connect the shaft to other drive line components. The yoke might be rigidly welded to the shaft tube or it might be a spline, or slip yoke. The tube yo
14、kes are connected through universal joints to end yokes on the output and input shafts of the transmission and axle. When the car rounds a curve, the outer wheel must turn faster than the inner wheel. To permit this, the two pinion gears rotate on their pinion shaft, transmitting more turning moveme
15、nt to the outer side gear than to the inner side gear. Thus, the side gear on the outer-wheel axle turns more rapidly than the side gear on the inner-wheel axle. This permits the outer wheel to turn more rapidly while the car is rounding the curve， so that the side gears turn at the same speed as th
16、e ring gear, causing both rear wheels to turn at the same speed, also。 During one revolution of the ring gear, one gear makes two revolutions, one with the ring gear and another as the pinions walk around the other gear. As a result, when the drive wheels have unequal resistance applied to them, the
17、 wheel with the least resistance turns more revolutions. As one wheel turns faster, the other turns proportionally slower. The differential case is supported in the carrier by two tapered-roller side bearings. This assembly can be adjusted from side to side to provide the proper backlash between the
18、 ring gear and pinion and the required side bearing preload. This adjustment is achieved by threaded bearing adjusters on some units and the placement of selective shims and spacers on others. It is to be noted that simple universal joint does not transmit the motion uniformly when the shafts are op
19、erating at an angle, except in constant velocity type universal joint. Because the pivot pins do not revolve in the same plane, the driven shaft will increase to a maximum and decrease to a minimum twice in each revolution. Although the degree of variation is small, however, it may be minimized by t
20、he use of two universal joints. The two joints are arranged so that the non-uniform rotation of each joint tends to neutralize that of the other. The propeller shaft is a driving shaft that connects the transmission to the differential.The output shaft or main shaft from the transmission and pinion
21、shaft extending from the differential unit are connected to the propeller shaft and the universal joints. A sliding joint is also used between the propeller shaft and the universal joint near the gear box. The rotary motion of the transmission main shaft is carried out through the propeller shaft to
22、 the differential, causing, the rear wheels to rotate.The propeller shaft has to withstand the torsional stresses of the transmitting torque, and yet it must be light and well balanced so that vibrations and whip will not occur at high speeds. For these reasons, it is made of a strong steel tube. So
23、lid propeller shafts are also used. The propeller shaft may be exposed to the atmosphere or protected by an outer tube. Some applications include bearings at or near the propeller shaft centre to support the shaft. On some applications, the propeller shaft is in two sections, supported by a centre b
24、earing and coupled together by universal joints. It is to be noted that the transmission main shaft and the differential pinion shaft are not in one horizontal level. The rear axle housing with differential is attached to the frame by springs, therefore the distance between the gear box and the diff
25、erential changes due to road irregularities. This also changes the angle of drive. In order that the propeller shaft must take curve of these two changes it is provided with one or more universal joints to permit variations in the angle of drive. Also, it must be provided with a sliding joint that permits the effective length of the propeller shaft to change.
