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Loads up to 15 tons

Maintenance-free standard polymer plain bearings for root ball transplanters

Root ball transplanters are indispensable tools for tree nurseries and for garden and landscaping businesses. They gently transplant trees of any size. Hydraulic cylinders are used to slowly, but with immense force, push the spades into the soil, cleanly severing the roots. Maintenance-free polymer plain bearings demonstrate their strengths in all areas that involve rotating and swiveling movements. They are maintenance-free, work under dry-running conditions and are particularly insensitive to dust and dirt.

"When a tree nursery transplants up to 1,000 trees each day, a root ball transplanter is always involved. The equipment must be rugged and reliable“, explains Roland Schlesag, General Manager at Optimal-Vertrieb Opitz GmbH, a family-owned business with 15 employees. "Our compact root ball transplanters are in use world-wide. “ We have been making these at our Thalmässing facility for almost 40 years. From A, as in Azerbaijan, to Z, as in Zambia, we make sure that trees are no longer tediously transplanted with time-consuming manual labor, but by machinery instead. "Our machines are extremely rugged", claims the General Manager. "For many years, this has been assured by maintenance-free polymer plain bearings. These are used in the hydraulic spade guides, various hinges and locks and also in the linkage between the primary and pivot arm. This allows us to guarantee low maintenance expenses and longer service intervals to our customers. “

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

For nearly ten years, the agricultural engineering company has been relying on iglide® G300 from igus® GmbH, Cologne. The all rounder bearing is particularly insensitive to external influences. More than 650 dimensions are available from stock. "And we make full use of this spectrum", states the mechanical engineer, Reiner Irsigler. "There is almost no dimension that we do not use in our broad model range. In addition, the price/performance ratio is also spot-on, which of course makes economic sense. “

Engineering and mobility

Dieter Opitz, the company's founder, set a milestone for the garden and landscaping industry by developing and producing modern technology for transplanting purposes. The machines were developed in the sixties and brought about enormous labor savings. Today, tree nurseries and landscaping businesses could not operate without these machines. Cleanly severed roots, tree conforming root ball shapes, gentle work in rows and reliable transportation: the tree transplanters ensure smooth and time saving operations at a very favorable cost/benefit ratio.

In addition to functionality, reliability and flexibility are among the crucial characteristics taken into account during the technical design phase. These are particularly compact machines that can be mounted on a variety of hauling equipment depending on need, and can be maintained with a minimum of effort. Even fully customized special purpose equipment is possible.

Today, an appropriate solution is available for any tree. The product range comprises twelve tree transplanters. They can dig root balls ranging in diameter from 36 cm to 2.50 m with a root ball depth from 30 cm to 1.50 m. Transplanting campaigns are generally scheduled for the spring and the fall. "When the season ends, the machine is normally cleaned with a steam jet and at best stored in a hall", Roland Schlesag states. "Since plain bearings are self-lubricating, the trouble spots will not incur storage damage due to the good dry-running properties. We rely on hard-chromed materials for the bolts. We believe that this is the ideal pairing that guarantees rugged machine engineering. “

Plain bearings for rotating and swivel movements

The ideal root ball transplanter will handle trees with considerable care. Their low working height permits trees to be removed without causing damage. The root ball matches the shape of the natural root growth. The favorable spade geometry and clean cut facilitates an accurate shape. The root ball stays intact, as it is fully enclosed by the spade. The low weight of the mounted equipment limits damage to the soil and roots.

Agricultural engineering requirements place particular emphasis on the absence of lubricants and long service life. Root ball transplanters place loads on iglide® G300 plain bearings primarily during swivel movements. In detail, this involves gimbal mounted hydraulic spade cylinders, as well as hinges and locks for the opening and closing frame components. On large machines that are mounted on trucks, plain bearings in the joints also ensure a secure connection of the primary arm with the swivel arm.

The highest loads are placed on the machine elements in the areas of the gimbal mounted spade cylinders when the four spades are steadily pushed into the soil with considerable force. A spade on one of the larger machines can theoretically push down with a force of 15 t. The means that a force of 150,000 N is applied by the hydraulics: the equipment is not treated with kid gloves.

The transplanting hole is dug using the root ball transplanter. The transplanting hole is also dug using the root ball transplanter.
The roots are cleanly severed when the root ball transplanter digs out the tree. The roots are cleanly severed when the root ball transplanter digs out the tree.

"We have had nothing but the best experience in this area with the plain bearings", states Reiner Irsigler in this regard. "They will hold up to the enormous surface pressures over time. This is in addition to their lack of lubricants, which is proving itself in daily use, whereas the soil permanently bonds to lubricated machine elements. Over time, the soil incrementally penetrates the bushings, creating friction and ultimately resulting in a failure. “

Moisture and soil have no influence of any kind on the functionality of the individual machinery components. Moisture and soil have no influence of any kind on the functionality of the individual machinery components.

The areas where the spades enter into the soil are also subject to any imaginable abrasive loads. Moisture and a broad temperature spectrum are topics that can also not be ignored. "The tree transplanting campaign that took place in the winter of 2011/2012 in the Stuttgart Schlosspark as part of the new rail station construction was subject to a very tight timeline. In addition, the temperatures were in a deep freeze“, Roland Schlesag recalls an actual episode. "None of the machines we used experienced malfunctions of any kind. “ In addition, the tribo-optimized plain bearings are able to handle any edge load without difficulty, for instance when the spades impact rocks.

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

No more in-house production

"In the past, we laboriously manufactured the required bearings in-house from red brass, which naturally impacted the installation space", Reiner Irsigler reminisces. "For one, wall thicknesses of 2 mm were simply not possible. We also constantly needed to produce ahead of schedule, which was economically not feasible over the long haul. Today, it only takes a phone call and the required components are available on site within one business day. " This allows us to avoid the grease nipples at the machine's trouble spots, as well as the costly storage of components produced in-house. "The iglide® bushings are shipped directly from stock. They are mature, tested and meet our high requirements profile", the General Manager confirms.

The root ball transplanter uses tribo-optimized cylindrical standard plain bearings made from iglide® G300 materials in a host of available dimensions. These are simply ordered from the catalog. The application spectrum is always the same on all machines, allowing the agricultural engineering firm to rely on standard solutions. "It simply works", comments Dirk Lanuschni, the responsible igus® sales consultant. "The iglide® G300 material is known as an all rounder. It comprises a broad spectrum of possible applications and is characterized by high wear-resistance and low friction values. “

This also includes another engineering detail that plays an important role and underscores the versatility of polymer plain bearings: "At some point the single-sided load will cause a red brass bushing to wear, which impacts tolerances. The clearance continues to increase until a bolt fails. Even though we used to use hardened bolts, for instance in the hinges, they still failed", the mechanical engineer recalls. "Bolt failures are now a thing of the past. The softer plastic material yields elastically, which completely avoids the notch damage that is the starting point for a failure. “

Heavy-duty applications for iglide® G300 plain bearings

In this application, the tribo-optimized iglide® G300 plain bearings demonstrate their versatility under the most adverse conditions. In spite of all adversities, they prove their long service life primarily in the hydraulic cylinders of the spades, when these are slowly pushed into the soil. "We provide engineering for professionals. Our objective is to produce quality made in Germany for our customer world-wide", Roland Schlesag confirms in conclusion. "And the maintenance-free and dry-running plain bearings have an important role to play in this. “

From left: Uwe Sund (igus® GmbH), Roland Schlesag (General Manager at Optimal-Vertrieb Opitz GmbH), Dirk Lanuschni (igus® GmbH), Reiner Irsigler (Mechanical Engineer at Optimal-Vertrieb Opitz GmbH).
3D rendition of the guide box: a host of applications for polymer plain bearings. 3D rendition of the guide box: a host of applications for polymer plain bearings.

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