Biso’s 3D Varioflex Air i is the German firm’s first Vario header with a flexible knife. A key feature of the new table is that it can actively control the cutting height while maintaining the cutting angle, as we found out in a rather damp Slovakia

Although headers with a flexible knife were developed for groundhugging crops like soybeans, they are proving invaluable for getting under lodged cereals when conditions get tricky, just as last year. Most of these headers rely on a conveyor belt to direct the crop from the knife to the combine, as on Claas’s Convio Flex in last month’s practical test. However, the Austrian header maker Biso is remaining faithful to an intake auger with its new 3D Varioflex Air i.

To see how it works we headed to Slovakia to combine soybeans, but the pesky weather wasn’t playing ball. With conditions damp underfoot and the crop moisture too high, we were restricted to combining a short run. Even so, this was enough to examine the new combine front. Constant cutting angle The knife is linked to the table body by a parallelogram linkage, one for every 90cm, meaning our 10.70m header had a total of 12 linkages.

These allow the knife to adapt to the ground contours with 170mm of movement. Unlike headers with traditional single-arm attachment, the 3D Varioflex maintains a consistent cutting angle, which is good for crop flow and prevents it from bulldozing the soil. Biso points out that the minimum cutting height is 25mm, which should be sufficient for soybeans and peas and most other crops grown in Northern Europe.

Sections between the individual parallelogram linkages offer nearly the entire travel range. In theory Biso reckons that the system could compensate for even more dramatic changes in terrain, but the limiting factor is the amount of flex in the cutterbar itself. As a side note; Biso buys the cutting system from Schumacher, with the steel guards bolted to the top and bottom of the blade sections, a design that is claimed to offer the best flexibility.

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