Tractive Performance of a Mechanical Front-Wheel Assist Tractor as related to Forward Speeds

A mechanical front-wheel assist tractor was instrumented to investigate the effects of tractor forward speed on the dynamic traction ratio, tractive efficiency and the ratio of axle load to axle input power. The tractor was tested at three operating speeds and under two distinct tractive soil surfaces: a stubble field and a disc ploughed field. Analysis of the results showed that with no change in the primary tractor mass, and by selecting the appropriate highest gear ratio, a tractor can be operated at its optimal tractive performances, and at the same time, higher work efficiency may be achieved. This study indicates that the ratio of dynamic load to input axle power varies according to speed and drawbar pull and does not reflect the ratio of tractor static load to rated p.t.o. power. The reported field data are mainly applied to high draft implements that use full tractor power.