机械毕业设计英文外文翻译549载货汽车主减速器文档格式.docx

1、Truck Main Reduction GearIn the highly competitive period following the energy crisis of the early 1970s, the automotive industry had to shift attention increasingly towards improvement of the quality of the product, yet still keeping its prices as low as possible. Prior to that GKN Axles Ltd, to ta

2、ke optimum advantage of economies of scale, had been producing at highly competitive prices a standard range of axles of different types and sizes, from which all customers needs could be satisfied. Because vehicle manufacturers had not hitherto had to place such a great emphasis on fuel economy, an

3、d therefore on light weight, these standard axles could cater reliably for all conditions likely to be met in a wide variety of applications. Now vehicle manufacturers require axles designed and developed for their specific applications. As axle design is becoming increasingly specialised, customers

4、 are increasingly raising their aspirations in terms of performance an reliability. For this reason, they are turning to specialists such as GKN Axles Ltd who have the ability to provide axles for a wide variety of vehicles。Since the 1970s, however, in common with virtually all other suppliers to th

5、e high volume producers in the motor industry, GKN has radically modified its approach to suit the prevailing conditions as they change through the 1980s and on into the 1990s. Its aim now is at supplying complete axle assembles, including, for example, the brakes, all designed and fully developed f

6、or and integrated, as a matter of course, into specific vehicle designs including, in particular, those for the specialist market. Emphasis is now on rationalization of materials, methods and components. This overall change has been necessary because of the greatly in creased sophistication demanded

7、 of the modern vehicle, in terms of overall efficiency, compactness, light weight, reliability, durability, refinement and maintenance-free operation. Another area into which GKN Axles has expanded is the supply of components and assemblies such as limited-slip differentials, ball-joints, transfer b

8、oxes, gears and some types of suspension.For off-road operation, the duty cycles may be entirely different in both torsional and beam loading-denpending on the application. For example, some types of vehicle spend a considerable proportion of their running time at high torque in low gear. In most ci

9、rcumstances, the terrain may be such that the tyres tend to slip more readily than on tarmac; in others, however, for example in fairly firm sandy screes, it may allow tyres to bite into it, and thus lead to torsional fatigue loading significantly greater than on smooth roads. Vertical and lateral l

10、oading, too, may be much more severe, though this dose depend to a major extent on speeds. Shock loading can also affect braking and acceleration torques though, again, such effects are speed-dependent. Hypoid gear systems are more commonly used than spiral bevels. Their principle advantages are tha

11、t pinions of a specific ratio are bigger, their teeth profiles are of large radius, they are inherently stronger and more durable, their meshing areas are larger, and they generate less noise Host reduction gear effect is to be used to reduce the rotation rate that the transmission shaft sends in bu

12、t to enhance revolution moment of torsion , changes drive direction with moment of torsion , passes on to half axes after differential mechanism and. The host reduction gear structure form is that the form is different but different according to gear wheel type , reduction gear mainly. Host reductio

13、n gear gear wheel has helix cone forms such as gear wheel , hypoid gear , column gear wheel and worm gear worm mainly.Pair of level host reduction gear is compared with single stage , the gap may be 7 12 transmission ratio , i0 each other at the same time in swear to be away from a field 12. But the

14、 dimension , mass are without exception bigger , cost is higher. It applies to middle, heavy type freight train , go-anywhere vehicle and motor bus mainly go ahead.Dyadic overall pair of level host reduction gear has the various structure scheme: First order is a cone gear wheel , the second stage i

15、s a column gear wheel; First order is a cone gear wheel , the second stage is epicyclic gear; First order is epicyclic gear , the second stage is a cone gear wheel; First order is a column gear wheel , the second stage is a cone gear wheel.Horizontal , askew, face and droop over to the three kinds t

16、o first order for the cone gear wheel , the second stage are that pair of column gear wheel level betokens reduction gear, but has direction arrangement scheme.Direction level arrangement can use the assembly drooping over to outline dimension diminution , reducing the automobile quality heart altitude thereby, makes the direction dimension increase by but , that the use on long distance between shafts automobile but appropriate diminut