17 November 2000

ARTIC – POWER WITH AGILITY

Having completed all but a few hundred acres of its massive

autumn workload, one Oxon contractor is pleased with

the performance offered by John Deeres 425hp artic machine,

the 9400. Geoff Ashcroft reports on the tractors progress

WITH John Deeres most powerful articulated tractor – a 425hp 9400 model – used as the prime mover on 1410ha (3500 acres) of cultivations work, Oxon contractor A&R Parker has been able to keep ahead of the game this year with its cultivations workload.

Only a few hundred acres of linseed that were still to be combined prevented the firm from wrapping up its autumn drilling programme in good time.

"Theres no doubt that weve been able to take on additional work this season to fully utilise the big Deere and still keep up with the workload," explains Richard Surtees, who spends his days behind the wheel of the 425hp articulated machine. "If our customers could have cleared the crops from their fields, we would have finished cultivating and drilling in plenty of time."

The contracting firm bought its 9400 John Deere as an ex-demo machine last summer, to replace its previous 260hp JD8640 artic that was proving under-powered when discing on steep banks.

Despite buying more horsepower than was initially planned, the most powerful articulated Deere currently available has been on its knees on more than one occasion this autumn.

"We have been waiting for Gregoire Besson to build us a new 6m wide disc/tine/press combination, complete with conical discs to improve inversion and reduce smearing, but we had to hire a set of discs from the firm to see us through this autumn," he says. "We had to take what was available, with hindsight, they were just a shade too wide. In damp conditions, the extra draft of the discs saw wheel slip increase to unacceptable levels, so ballast went up from 40kg/hp up to 43kg/hp to reduce wheel slip to below 12%."

The hired discs amounted to a 6.5m set, complete with 13 sub-soiler tines, followed by a press roll – an outfit that proved just a bit too much on the slopes, even for a tractor capable of developing a peak power output of 455hp.

"Climbing some of the steep banks we are asked to cultivate, the combination was just a bit too much to pull. It has held back our output simply because we couldnt maintain 10-12kph all the time," says Mr Surtees. "But the powershift transmission has meant we could simply keep coming down the box and maintain progress when the going got really tough. I hope the narrower set of discs being built will allow us to maintain that critical forward speed when going up the slopes."

Yet for all its bulk, the Deere offers a light footprint when shod on 710/70 R38 dual J wheels running at 6psi, and it also has the ability to turn on a 12m headland, even with the 6.5m disc/press combination in tow.

Despite the reduced forward speed from the over-sized set of discs, the firm has still been able to cultivate an average of 40ha (100 acres) per 12 hour shift (including moves and refuelling), with spot work rates reaching 8ha (20 acres) per hour – enough to keep on top of the work load once fields were cleared and ready to cultivate.

"When weve been really busy, weve only had to run two eight hour shifts because 24-hour operation has not been required," he says. "In some instances, a 12-hour shift has seen enough ground cultivated to stay in front of a pair of Vaderstad drills pulled by our 260hp Deere 8640 and a Magnum Pro 7220."

Now into its second season with A&R Parker, and with about 800 hours on the clock, has the big Deere been the right choice?

"Yes, without a doubt," he adds. "Weve only had three hours of downtime all year, and that was caused by a burst intercooler hose. The machine has lived up to expectations and in some instances, it has exceeded them."

Fuel consumption, for example, is an area where the Deere has excelled itself.

"We were ready for an increase in the fuel bill, but were surprised to find it can use less than a gallon/acre on easy going land," says Mr Surtees. "However, in heavy going, it does have the ability to gulp through over three gallons/acre."

"Had we not bought the tractor for a keen second-hand price, we could not justify running it, even on almost 4000 acres of cultivations work," he says. "But the system we have works very well."

And recognising that disc harrows dont suit everyones field conditions, Mr Surtees expects to add ploughing to the 9400s workload.

"A 10-furrow reversible would just help keep our options open, and it would also mean winter ploughing can be offered, which could take some of the heat out of the autumn workload," he says. &#42

A&R Parkers operator Richard Surtees (below) finds the 425hp artic Deere a surprisingly agile tractor for its size. "The powershift transmission is essential for heavy draft work."

Hired Gregoire Besson 6.5m disc/tine/press combination proved power-sapping – even for a peak of 455hp – on the banks. New 6m version should ease the strain next season.