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• waiting for mill delivery <strong>of</strong> empty bins<br />
• servicing and repairs<br />
• moving between fields<br />
• “cutting in” to new fields where harvesting rate is slow because the harvester tows a reversing<br />
haulout directly behind it into the field<br />
• choking <strong>of</strong> material in the harvester<br />
Time lost turning obviously relates to both the time taken for the harvester and haulout to turn at the<br />
end <strong>of</strong> the row and achieve correct positioning to allow the harvesting process to re-commence. It is<br />
therefore effected by:<br />
• maneuverability <strong>of</strong> the harvester and haulouts<br />
• available space for this maneuvering (headland width)<br />
• length <strong>of</strong> row and crop size, therefore affecting the number <strong>of</strong> turns which must be executed in<br />
daily allocated cutting.<br />
Row length is outside the control <strong>of</strong> the harvesting contractor. Short rows decrease the efficiency <strong>of</strong><br />
a harvesting operation significantly because turn time is fixed. That is, less time is spent cutting cane<br />
for each turn when row length is reduced.<br />
Time lost waiting for haulouts relates to haulout capacity, speed <strong>of</strong> travel to the unloading node,<br />
unloading time and return time to near the harvester. This is therefore effected by:<br />
• haulout speed, loaded and unloaded on both field headlands and formed roads<br />
• distance to the delivery point<br />
• unloading time at the delivery point<br />
Field efficiencies are an important measurement in the analysis <strong>of</strong> harvest cost and harvest transport<br />
systems.<br />
The Australian cane industry has developed methodologies for measuring field efficiency. These<br />
include electronic systems using on-board electronic measuring equipment, data loggers and GPS<br />
systems. The typical field efficiencies for various crop sizes are shown in Table 2.8. These data are<br />
aggregated from the Maryborough, Mackay and Burdekin regions.<br />
Benchmarking <strong>of</strong> Australian harvesting operations has been by undertaken by Sandell and Agnew<br />
(2002) and Willcox (2004). Table 2.8 shows the percentage <strong>of</strong> time actually spent cutting cane from<br />
the total daily operation from two seasons in the Maryborough, Mackay and Burdekin regions. This<br />
shows that on average a little over 50% <strong>of</strong> the time the machine is actually cutting.<br />
Table 2.8 Field efficiency for various crop sizes (Willcox, 2004)<br />
Crop Size Crop Size Field Efficiency<br />
t/ha t/km row* %<br />
60 10.8 53<br />
80 14.4 52<br />
100 18.0 52<br />
58