With its double star roller said to be capable of producing seedbeds in heavy soils in a single pass, Rau’s ground-driven Sterntiller was heralded as an alternative to pto-driven tillage equipment. Last autumn we put the 6m trailed cultivator combination, complete with double star rollers, through its paces – in oilseed rape stubble
Star rollers are a simple but an ingenious idea. A total of 366 tines, welded in sets of four to a pair of shafts in a star-shaped pattern, are designed to mix the soil, create a good tilth and firm the soil to just below seed planting depth. The two shafts are aligned so that the ‘star’ tines intermesh, providing a degree of self-cleaning.
Designed to level up the soil surface between the tractor wheelings, the first component on this 6m wide trailed combination is a W-shaped, spring-loaded board. The whole of the combination is then divided into two 3m wide wing sections for an easier hydraulic fold.
The next part of the Rau machine comprises two rows of 20 ‘pig-tail’ spring tines. Set at 30cm centres and fitted with 20cm wide duck foot shares, these perform a good job of loosening and mixing the soil. Next in line are the double star rollers; each pair of star rollers is suspended on adjustable, spring-loaded rocker arms from the same frame as that used for the spring tines – a system that allows the star rollers to follow ground contours. Spring tension on the roller arms is adjusted using set screws and locking nuts.
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