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

Profile

• What was needed: Polymer plain bearing made of the material iglidur G
• Requirements: Lubrication-free and a long service life; robust components that can withstand up to 150,000 N of force; resistant to heavy moisture and temperature fluctuations
• Industry: Landscaping and horticulture
• Success for the customer: The customer no longer has to carry out costly production and lubrication themselves; iglidur G offers high resistance to pressure and wear; due to the robust and at the same time elastic property of the bearings, breakage points are completely avoided

The spades are pushed slowly into the soil. The polymer plain bearings are able to deal with dirt, moisture, etc.

Problem

Tree transplanting machines, so-called root ball cutters, enable a smooth and time-saving application with an excellent cost-benefit ratio. Today, it is impossible to imagine the landscaping sector without machines like those from Opitz.
Plain bearings are used in a wide variety of places on the machines. This is also the case with the gimbal suspension of the hydraulic spade cylinders as well as the hinges and the lock of the opening and closing frame parts. In addition, on the large machines that are mounted on lorries, plain bearings in the pivot points ensure a secure connection of the main arm with the pivoting arm.
The technical design of the root ball cutters takes into account above all functionality, durability and flexibility. For the plain bearings used in the machines, the focus was therefore primarily on freedom from lubricants and a long service life.
Especially the spades, which are continuously pushed into the soil with high force, need strong components. A spade of a larger machine can theoretically push down 15 t, using up 150,000 N of force.
In addition, the issues of humidity and broad temperature spectrum play an important role in the choice of components.
The previous solution was elaborately manufactured in-house from gunmetal. In addition to the time-consuming work involved, the bearings also had to be lubricated, which had a negative impact on the environment. On the other hand, the gunmetal bearings required a relatively large installation space, as wall thicknesses of 2 mm are quite common.

Solution

Tribo-optimised cylindrical standard plain bearings made of the iglidur G material are used in many available dimensions in the root ball transplanters. They are used in the hydraulic spade guides, various hinges and locks as well as in the connection between the main arm and the pivoting arm.
Polymer plain bearings made of the material iglidur G can eliminate the need for costly production and additional lubricants. This eliminates the environmental impact of additional lubricants when the root ball cutter penetrates up to 2.5 m deep into the earth. iglidur G impresses in this application with a high resistance to pressure and wear. Thus, the service life of the bearing points could be increased.
Also decisive for the use of the polymer bearings: A gunmetal bushing will eventually fail under the one-sided load, which leads to higher tolerances. The clearance continues to grow, until a bolt gets broken. Despite the use of hardened bolts for the hinges, they are broken. The softer plastic material, on the other hand, yields elastically, and breaking points are completely avoided.
When the season ends, the machine is usually sprayed with a steam cleaner and is best stored indoors in winter. And since the plain bearings are lubrication-free, no damage can occur in storage due to the good dry running properties at the critical points.
For almost ten years now, the agricultural technology company has relied on igus' standard material iglidur G. The all-rounder bearing is very resistant to external influences.

Up to 1000 trees can be transplanted in a day with a root ball transplanter.

When digging with the root ball transplanter, the roots are cut neatly.

Moisture and soil have no influence on the functioning of any of the individual machine components.

Polymer plain bearings in the various hinges, locks and hydraulic cylinders of the root ball transplanters.