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

Tree transplanting machines, so-called root ball lifters, 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 in the most diverse areas of the machines. For example, in the gimbal suspension of the hydraulic spading cylinders as well as in the hinges and the locking mechanism of the frame parts that open and close. In addition, plain bearings in the pivot points of the large machines, which are mounted on trucks, ensure a secure connection between the main arm and the swivel arm.
Functionality, durability and flexibility are the main factors taken into account in the technical design of the root ball lifters. For the plain 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 downwards 15 tonnes, using 150,000N 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 an impact on the environment. On the other hand, the gunmetal bearings required a relatively large installation space, as wall thicknesses of 2mm are quite common.

Tribo-optimised cylindrical standard plain bearings made from the material iglidur G are used in the root ball lifters in a wide range of available dimensions. They are used in the hydraulic spade guides, various hinges and locking mechanisms as well as in the connection between the main arm 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 root ball lifter penetrates up to 2.5 metres into the ground. iglidur G impresses in this application with its high pressure and wear resistance. As a result, the service life of the bearing points was able to be increased.
Another decisive factor in the use of polymer bearings: A gunmetal bushing will eventually fail under 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 preferably stored indoors for the winter. And as the plain bearings are lubrication-free, no damage can occur at the critical points due to their good dry-operation properties.
For almost ten years now, the agricultural engineering company has been using the igus standard material iglidur G. The all-round bearing is particularly resistant to external influences.