Good road holding thanks to plastic bearings

• What was needed: iglidur ® J, drylin®-W
• Requirements: Low coefficient of friction, wear resistance
• Industry: Agricultural engineering

When it comes to nutrition, dairy cows are very demanding. This applies to the quantity, but even more so to the quality of the feed. They need around three per cent of their own weight in dry feed per day. As soon as their composition changes, the complex digestive system of ruminants reacts with a lower milk yield. One of the daily challenges for a farmer is therefore to produce a consistent feed quality and mixture from the individual components of grass, hay, silage and concentrated feed.
Professional farms use feed mixers for this task. Farmers who attach great importance to quality, efficiency and productivity often opt for vehicles from Mayer Maschinenbaugesellschaft mbh, which are produced in Tittmoning in Bavaria and sold worldwide under the brand name Siloking.

Siloking is regarded as an innovation leader in feeding technology and has recently developed a new generation of the top models among self-propelled feed mixer wagons - vehicles with their own drive and cab. The "SelfLine 4.0" series is characterised by a large number of innovations. These include energy-saving engines that comply with the latest international emissions regulations and are around 20 per cent more economical than their predecessors

The chassis of the mobile machines has also been redeveloped. The designers almost had to succeed in squaring the circle. In the barn, the vehicles have to be extremely manoeuvrable in a very confined space, while at the same time being able to cover long distances on the road. Correspondingly high demands are placed on driving safety and comfort. Siloking invests a great deal of expertise in vehicle development: more than ten per cent of the 280 employees at the Tittmoning site work in design and development. This made it possible to develop a new rear chassis with independent wheel suspension that fulfils the sometimes conflicting requirements in the best possible way

The respective wheel load is transferred via a hydraulic cylinder in the form of a hydropneumatic suspension from a suspension arm to the centre column. The lower control arm is designed as a guide control arm and only transmits lateral forces from the wheel. The arrangement of these two control arms gives rise to the term 'double wishbone axles'. In order to prevent self-steering behaviour of the wheels, it is necessary for the track rods to have the same length as the suspension and control arms. In order to realise the smallest possible track width, the steering cylinder attached to the piston rod is supported by a parallel guide with igus® plain bearings. To be more precise, these are maintenance-free cylindrical bearings of type FJUM-02-50 made of iglidur® J with incorporated lubricant. It is very wear-resistant and is characterised by its very good coefficient of friction and vibration-damping specification, among other things. The low moisture absorption ensures perfect operation even in humid environments. All in all, the suspension ensures that the self-propelled vehicle runs smoothly and stably both on poor roads and when travelling fast on the road.

Maximilian Hauser, designer of the wheel suspension, explains the selection criteria for the bearing: "A plain bearing is the better choice here than a linear guide with balls, where even lubrication is not guaranteed due to the short stroke." The bearings made of iglidur® J also proved to be wear-resistant in tests with high loads under adverse environmental conditions. The hard chrome-plated shaft with a diameter of 50 millimetres ensures an ideal counter-rotation pairing and forms a cost-effective solution in combination with the iglidur® J bearings.

The new independent wheel suspension is standard on the largest machine in the new series - the SelfLine 4.0 Premium 2215-22 - and is available as an option on the other models. But even the machines equipped with the traditional three-point chassis cannot do without igus® plain bearings. For example, the milling flap is mounted with igus® plain bearings to protect the milling drum, as are the angle sensors for the hydraulic levelling system. Another bearing from the igus® modular system is located directly in the driver's field of vision: the central 7-inch display and the operating unit for the programming scale are attached to a vertical drylin® W-linear guide and are therefore height-adjustable. The standard programming scale also shows how important the exact composition of the forage is: The milling head of the Siloking machines can be equipped with an NIR scanner, which uses the principle of near-infrared spectroscopy to record the dry matter content of the forage in real time during forage removal. This allows the farmer to make precise adjustments immediately and provide the cows with exactly the feed that they like best.