Shock-resistant polymer bearings for tine arms in rotary swather

AGCO Feucht GmbH (then known as Fella-Werke GmbH) has been designing working machines for tractors for over 90 years. These include mowers, tedders and rakes. The function of the rake is to rake mown or already spread forage into a swath with eight, ten or twelve tine arms. All rakes from this supplier work exclusively with rotor technology, which has the advantage of a high area output, among other things. The most important function of the machine is the mounting of the tine arms as part of the complex control system. Two plain bearings are installed on each tine arm. If damage occurs here, the roundabout rake stops, which must not happen at harvest time under any circumstances.
During the peak season in summer, agricultural harvesters have to work smoothly for many hours every day for a few weeks. The external stresses are extremely high. The transport of the crop over the ground, but also the contact of the tines with the ground or collisions with obstacles such as bushes, hedges and stones, primarily generate radial forces. To prevent damage to the plain bearings in these situations, they must be impact-resistant and very robust. Added to this are dust and dirt and, finally, high-pressure cleaning. Rough operation and long service lives with possible corrosion of the steel parts place very high demands on the plastic plain bearings.
The machine manufacturer's ultimate goal was to find a compact and cost-effective solution.

Tribo-optimised polymer plain bearings made of the special material iglidur® G have been used as plain bearings for ten years now. These are economical all-round bearings, which - lubricant and maintenance-free - prove their strengths in simple swivelling and rotating movements, at very high loads and with high dirt
requirements. The system has been running smoothly since the series launch. The anti-rotation feature ensures that the bearing bush is one hundred per cent firmly seated in the mount. The advantages pay off for the agricultural machinery manufacturer: wear has been significantly reduced compared to metal plain bearings and there is less noise during operation. In addition, the cost-effectiveness is right, as there is no need to rework the housing bore for the plain bearings in the aluminium bearing tube. The plastic bearing with the conical outer side was simply adapted to the conical type of the housing bore. This also applies to the conical mounting holes of the aluminium bearing tubes, which are screwed to the cone of the gyro bells.
The company quickly realised that costs could be saved with plastic. Initially, the company turned plastic bushes itself and later had them injection moulded. As the choice of material was not right, the result was not right either. The right solution was then quickly found from the extensive igus® product range, which includes standard and special parts. The high abrasion resistance and dry-running properties of the polymer plain bearings, which have been tested thousands of times under everyday conditions in the igus® laboratory, were immediately convincing in agricultural practice.