General Guidelines for Tractor Weight Based on Engine Horsepower (according to EC Directive 97/68, using PS as Unit of Measurement)

The total tractor weight needed to efficiently deliver power through the wheels to the ground for field draft applications depends on travel speed and soil conditions. As a basic guideline, the table shows the recommended weight per engine horsepower [PS]¹ for several draft speed range and speed thresholds for heavy pull.

Indicated Travel Speed

Wheel slip should normally be in the range of 8 – 12% for optimum efficiency of power delivery at these field speeds. Wheel slip may briefly rise above this range when the tractor encounters a higher draft area in the field, but it should not remain there continuously.

NOTE: Radar is recommended to continually monitor wheel slip. Checking wheel slip manually is possible but will not show slip continuously.

IMPORTANT: To extend drive train life, the tractor should never be operated with continuous full-power loads at speeds below 6.6 km/h (4.1 mph) with front-wheel drive engaged, and below 7.0 km/h (4.3 mph) for tractors without front-wheel drive. Some tractor models which are optimized for special applications can have different speed thresholds (see table for more specific values). Ground speed may drop below that level in hard-pull situations, but it must recover to higher levels during normal operation. This applies to tractors with all types of transmission. For tractors equipped with IVT™/AutoPowr™ transmissions operating in automatic mode, the engine will not labor in high draft situations, but minimum ground speed guidelines must still be followed.

The speed thresholds provided by the table can be used as an additional means to optimize the tractor weight for the application. The tractor is ballasted properly if wheel slip is increased and the engine cannot be stalled at speeds below these thresholds and under heavy-pull conditions.

Lower travel speed thresholds for heavy pull depending on vehicle type