Improving the Tractive Performance with Four-Wheel Drive (4WD) System

This paper gives a brief study of the components, operating modes, merits and demerits of a four-wheel drive system over two-wheel drive system, and a case study of Mahindra Scorpio S11 is done for tractive effort by 4WD and 2WD (front wheel drive). The results for Mahindra Scorpio S11 showed that the tractive effort by 4WD system increases as the gear ratio decreases, i.e., highest for reverse gear (14362.96 Nm) with gear ratio 3.28:1, 1st gear (13000.00 Nm) with gear ratio 2.97:1, 2nd gear (9066.67 Nm) with gear ratio 2.07:1 whereas lowest for 6th gear (2451.85 Nm) with gear ratio 0.56:1. Similar results for tractive efforts by 2WD (front wheel drive) system can be depicted, i.e., highest tractive effort for reverse gear (7674.07 Nm), 1st gear (6940.74 Nm), 2nd gear (4837.04 Nm) whereas lowest for 6th gear (1311.11 Nm). As observed, the tractive effort by a 4WD system is comparatively higher than a 2WD (front wheel drive) vehicle. Thus, this results into reduced wheel slippage tendency, better climbing capability in hilly areas and better driving control over the vehicle on the low frictional surfaces such as wet/snowy surfaces. Whereas additional components in 4-wheel drive system adds on weight; increases cost, maintenance, repair, noise and vibrations; and makes the construction comparatively more complex.