AUTOMOBILE RUNNING SYSTEM AND POWER TRAIN 10. DIFFERENTIAL AND REAR AXLES
In the conventional layout, power from the propeller shaft has to be turned by 90O to be given to the wheels. This is accomplished by the differential. It is placed between the two rear wheels. There are two more functions performed by the differential. It differentiates the speed of the wheels at turns and also increases traction by reducing the gear ratio by about 4:1. In the conventional layout, the differential is a set of bevel gears assembled in a housing. In front wheel drive cars such as the Maruti 800, where the axis of wheels is the same as that of the differential, bevel gears are not used. Instead helical gears are used. In the conventional layout, drive from the differential is transferred to the wheels via the rear half shafts also called rear axles. These are of different types and are classified on the basis of the loads carried by them and the placement of wheel bearings. We shall study about rear axles also in this lesson.
10.0
Objectives After going through this lesson, you will be able to: i. ii. iii. iv. v. vi.
10.1
Explain the necessity of a differential Differentiate between the differential used in a conventional layout and that used in a front wheel drive car. Describe the construction and working of a differential Differentiate between various types of rear axles Tell why full-floating axles are used in heavy vehicles Understand how the axles are held in place
Introduction
In the conventional layout, power from the engine is transmitted along the length of the vehicle till its direction needs a change by 900. The differential performs this function. It is generally mounted near the longitudinal center line of the vehicle between the powered wheels (rear and/or front as the case may be). In fact the differential has three functions to perform: