A WHOLE CROP HARVESTER FOR THE DEVELOPING-WORLD

A whole crop harvester has been developed in response to the demand from farmers in the developing world for a harvester to harvest the whole cereal crop, thresh and clean the grain, and process the straw into animal feed. Development started in 1983 with a single drum prototype which was tested in Egypt. It was established that a single drum could not achieve sufficient straw breakage without excessive grain damage. A test rig was subsequently built from which a multidrum design was developed. This was tested in Pakistan in 1985 and forms the basis of the current design. The current machine can be operated by a 40 kW tractor, provided the hydraulic lift capacity is sufficient. Power measurements show a typical power consumption of 9·6 kW for a throughput of 3 t/h whole crop (1·5 t/h grain). While spot throughputs of up to 4 t/h clean wheat have been recorded in the UK, it is expected that in Pakistan overall throughputs of around 1 t/h clean wheat will be more typical. With a 2 m wide cut, spot work rates of 0·6 ha/h and overall work rates of 0·4 ha/h are typical. Losses from the cleaner amount to 0·1-0·5% of clean grain, with a sample containing around 1% impurities. The separation efficiency of the threshing and separation drums is 98·99%, which means that 1-2% of the grain will pass to drum 3 and be processed to animal feed. Grain damage is typically around 2% but can be controlled by reducing cylinder speed. The broken straw processed by the harvester typically has a bulk density of 60 kg/m3 and a median length of 20 mm. The harvester is tractor mounted on Category 2 linkage. The table assembly, which is in-line for transport, rotates to the offset position for work. The table feeds a series of three drums which separates the grain and breaks the straw. Grain is cleaned by a cleaner, and bagged at the rear of the machine, while broken straw is bagged at the side or blown into a trailer. © 1997 Elsevier Science Ltd. All rights reserved.