2 November 2001

Deere doesnt do combines

in a small way

John Deere recently

launched a bundle of new

tractors and combine

harvesters. Andy Collings

took the opportunity to visit

the companys UK

headquarters at Langar,

Notts, and take a closer

look at the combines

MOST companies would be content to introduce one or maybe two combine harvesters in a season. John Deere has chosen to launch 10 for the 2002 season and, if that wasnt enough, there is also a new range of headers.

The new flagship model is the US-built 9880 STS which employs a threshing system not previously seen in the UK – a single core rotary system.

When the cut crop exits the intake elevator it passes through the Feed Accelerator Stone Trap (FAST) – a rotating cylinder which, as its name suggests, removes stones from the crop. No threshing takes place at this point.

The crop then enters the rotary separation area via a feeding system which splits the flow of the crop into three streams and, as a result, delivers it to different parts of the rotors circumference. This first section of the rotor can be likened to a conventional drum and concave – rasp bars on the 750mm diameter rotor separate the grain against a wire concave in a traditional manner.

The second, slightly larger diameter section of the rotor is equipped with tines which tease out grains from the straw. Crop movement along the rotor is achieved by placing angled deflectors on the housing ceiling.

Rotor drive is via a belt and variator pulley system – rotational speed can be varied from 210 to 1000rpm. Those who have had bad experiences replacing rotor drive belts need not fret, apparently. John Deere says a new belt can be fitted in less than 30 minutes.

Clear of the rotor, the crop is met by a final chance discharge beater which releases any remaining grains from the straw.

Meanwhile, grain and chaff is augered to the cleaning shoe and is dealt with conventionally by an air and sieve separation – albeit a high capacity system which can be set to deal with individual crop and harvesting conditions from the cab.

Power for the 9880STS is delivered by a Deere 12.5 litre Powertech engine rated at 465hp. Drive for components other than the rotor is initially by shaft with the whole threshing system clutched into action.

The STS has an 11,000 litre grain tank, 945 litre fuel tank and the option for a 30ft header.

For the operator, a plethora of electronic control systems help to maintain maximum output in a wide range of field and crop conditions. Pre-set header cutting height and automatic combine adjustment for specific crops are just for starters. A visual monitoring system for the settings of the cleaning shoe and a tachometer for ground speed, area harvested and operating speeds of components such as drum, fan or engine is also part of an extensive elecronics package.

The flagship combine – the 9880STS – complete with one of the new 600R headers which, available in widths from 14 to 30ft, are used throughout the John Deere combine ranges. Header features include a single drive shaft, quick coupler and 660mm-diameter auger. An epicyclic gearcase knife drive provides a true lateral motion rather than the arc movement created by wobble box drives.

John Deeres six-model 9000 WTS combine range is equipped with a rotor with retractable tines positioned over the latter third of the straw walkers to improve threshing performance. Five and six-straw walker models are included in the line-up which offers engine power from 206 to 336hp.