8 September 2001

Stepping on the power

Claas continues to push the performance potential of its Lexion range with more power and improved grain separation. Peter Hill reports

THAT combines on UK farms are polarising at the top end of the performance scale is clearly evident from latest Claas sales figures. The German manufacturers top two models, the Lexion 460 and 480, account for no less than two-thirds of the total number of combines the company placed on UK farms for this years harvest.

"Capacity and cost-efficiency are paramount as farmers try to minimise the cost of harvesting their grain," says Trevor Tyrrell of Claas UK. "Were still seeing farms rationalising their fleets, switching from three machines to just two, or from two combines to just one."

Little wonder, then, that the newest addition to the Lexion line-up slots neatly between the companys best sellers. The 470 uses twin-grain separation rotors like those in the range-topping 480 but packs them into a five straw-walker chassis. The result is a relatively narrow combine with top-notch performance.

Despite using the narrower of the Lexions two APS threshing and sieve set-ups, the newcomer is reckoned to pip the six-walker 460s output potential at 32 to 35t/hour in a package that can be driven along narrow roads with more confidence and less hassle.

"The 470 is really aimed at farmers and contractors who have to travel frequently between fields on the road," explains Paul Moss, Claas UK harvest machinery specialist. "With 800/55R32 tyres fitted, the 470 is 3.6m wide overall, 30cm less than the 460 and 480. And, of course, it can run on narrower tyres if this is still a problem."

Like all models in the Lexion range, threshing in the 470 model is done in three stages. First, a lugged drum takes out all the easily loosened grain, while accelerating the straw mat as it heads into the main threshing cylinder.

After the threshing cylinder has done its job, a beater drum takes out a bit more grain while dividing the straw so that it feeds cleanly into the two lengthways rotors. These have open concaves around three-quarters of each rotor housing, so that any loose grain is flung out by centrifugal force as the straw spirals its way to the back of the combine.

A new feature of this Roto Plus system, which is also included on 2002-spec Lexion 480 combines, is variator drive to the rotors. On current models, the operator has a choice of three speeds. But because switching from one to another involves slackening the drive belt and shifting it to another pulley, the rotors tend to be left running at the same speed for all conditions.

"The variator provides a greater range of infinitely variable rotor speeds, as well as push-button adjustment from in the cab," he says. "So drivers can now slow the rotors in dry, brittle conditions or speed them up when crops are a bit green or damp to get the best separation and maintain working speeds."

Grain removal is also the focus of two Evolution models in the Lexion range. On the 430 and 460, the two sets of familiar "walking finger" agitators above the straw walkers have been replaced by a single drum with a multitude of retracting tines.

"This is a much more active and aggressive system because of the large number of tines, the speed of the drum and the fact that the tines penetrate more deeply into the straw mat," says Paul Moss. "Weve seen output improvements of up to 10%, especially in green, damp or heavy yield crops, but with no loss of straw condition or quality – in fact, it sets up a really nice swath."

The Multi Separator System deploys 35 tines (compared with 10 fingers) on the five straw walker Lexion 430, and 44 tines (replacing 12 fingers) on the Lexion 460.

Lifting performance across the range is the increased power and torque that comes from changing to Cat diesel engines from Mercedes and Perkins motors. The engines are also said to be more fuel efficient thanks to electronic injection and management.