ABSTRACT
Transmission, the need for gear ratios to provide gradeability, acceleration and maximum speed, is considered in this chapter. Various gear ratios for light and heavy vehicles are analysed and the geometric series of gear ratio selection is shown to be appropriate for heavy vehicles. The picture is not so clear in light vehicles except that close ratios for the high ranges such as 4th and 5th gear appear from the analysis to be quite common. A main factor is that the range of gear ratios should allow the vehicle performance to match as closely as possible to the ideal tractive effort at each road speed. Various forms of gearbox such as splitter, range and twin clutch automatic receive attention.
