Up to 15 tons load - polymer plain bearings in root ball transplanters

• What was needed: Polymer plain bearing made of the material iglidur® G
• Requirements: Lubricant-free and a long service life; robust components that can withstand up to 150,000 N of force; resistant to high humidity and temperature fluctuations
• Industry: Landscaping and horticulture
• Success for the customer: The customer no longer has to carry out time-consuming production and lubrication himself; iglidur® G offers high pressure and wear resistance; the robust and at the same time elastic specification of the bearing completely prevents breakages

Tree transplanting machines, so-called bale cutters, enable smooth and time-saving use with a very good cost-benefit ratio. Today, it is impossible to imagine the landscaping sector without machines such as those from Opitz.
Plain bearings are used at various points on the machines. This also applies to the cardanic suspension of the hydraulic spading cylinders as well as to the hinges and the locking of the frame parts that move open and closed. In addition, slide bearings in the pivot points of the large machines, which are mounted on lorries, ensure a secure connection between the main arm and the swivel arm.
Functionality, durability and flexibility are the main considerations in the technical design of the bale lifters. For the slide bearings used in the machines, the focus was therefore primarily on freedom from lubricants and a long service life.
The spades in particular, which are continuously pressed into the soil with high force, require strong components. A spade from a larger machine can theoretically press down 15 tonnes, using 150,000 N of force.
Moisture and a wide temperature range also play an important role in the choice of components.
The previous solution was elaborately manufactured in-house from gunmetal. In addition to the high time expenditure associated with this, the bearings also had to be lubricated, which created a load for the environment. On the other hand, the gunmetal bearings required a relatively large installation space, as wall thicknesses of 2 mm are quite common.

Tribo-optimised cylindrical standard plain bearings made of the material iglidur® G in many available dimensions are used in the bale cutters. They are used in the hydraulic spade guides, various hinges and locks as well as in the connection between the main and swivel arm.
Polymer plain bearings made from the material iglidiur G eliminate the need for costly production and additional lubricants. This eliminates the environmental impact of additional lubricants when the bale cutter penetrates up to 2.5 m deep into the earth. iglidur® G impresses in this application with its high pressure and wear resistance. The service life of the bearing points could thus be increased.
Another decisive factor for the use of the polymer bearings: A gunmetal bushing fails at some point with the one-sided load, which leads to higher tolerances. The clearance increases until a bolt breaks. Despite the use of hardened bolts in the hinges, these are broken. The softer plastic material, on the other hand, yields elastically and breaks are completely avoided.
When the season finally comes to an end, the machine is normally hosed down with a steam jet and, at best, is stored indoors for the winter. And since the plain bearings are lubrication-free, no damage can occur at the neuralgic points due to the good dry-running properties.
For almost ten years now, the agricultural engineering company has relied on the igus® standard material iglidur® G. The all-round bearing is particularly resistant to external influences.