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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

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