Tractor Performance in Two- and Four-Wheel Drive

Abstract

ABSTRACT THE field performance characteristics of a 16.7 PTO kW tractor in two- and four-wheel drive configurations on three soil types were studied. It was found that maximum drawbar power increased from 45 to 124% in four-wheel drive, depending on soil type and condition. With the same two bottom plow, maximum field speed without excessive slip increased from 45 to 106%. Fuel consumption per hectare decreased from 25 to 57% in four-wheel drive as compared with two-wheel drive. An economic analysis indicated similar operating costs per hectare for plowing ten hectares per year with 16.7 PTO kW two- or four-wheel drive tractors, but the four-wheel drive offered a significant improvement in field capacity. Up until recent times four-wheel drive has been considered advantageous only with high horsepower tractors. For example, Dommel and Race (1964) proposed that tractors under about 37.3 kW should basically be two-wheel drive; tractors in the 37.3 to 89.5 kW range could be either two- or four-wheel drive; tractors above 89.5 kW should be four-wheel drive. However, low horsepower four-wheel drive tractors (10 to 20 kW) have been successfully introduced in recent years into the US. market. Justification of the additional initial cost and field studies to determine the tractive performance of the low horsepower four-wheel drive tractor have not yet been provided. Objectives of this study were: (a) to determine the field performance characteristics of a 16.7 PTO kW tractor in two- and four-wheel drive configurations on three selected soils, and (b) to compare the operating costs of a small tractor in two- and four-wheel drive.