Cranfield University

Experimental Methods
had been mounted on the front axle and 600/55-26.5 tyres on the rear axle. The front and
rear tyres were inflated to 2.5 and 1.4 bar, respectively.
Figure 4: The combine harvesters taken into the field
For the field trials both machines were equipped with a 9 m header and the traveling speed
of the machines was approximately 1 m/s, thus similar to soil bin speed. This slow speed
(in comparison to real working conditions) was necessary to target the measurement spots.
The aim was to make a relative comparison, not necessarily replicating exact harvest
speeds, and hence the speed itself is not significant on the relative difference as long as
both machines operate at the same speed. However, the speed in exact harvest conditions
could influence the outcome eventually.
2.1.2.3 Experimental Set Up
The initially planned treatments with numbers one to five (locations shown in Figure 5 and
Figure 6) were the tracked combine harvester with full (1) and empty grain tank (3), a
wheeled combine harvester with full (2) and empty grain tank (4) at recommended infla-
tion pressure for maximum machine weight and the wheeled combine harvester at +1 bar
on top of the recommended inflation pressure (5). This additional inflation pressure of 1
bar was selected because of theoretical ideas leading to an infield possibility to gain the
slope and intercept of the virgin compression line for the given soil type and conditions.
Ph.D. Thesis Dirk Ansorge (2007)
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