Case story

ROPA potato harvester: Accurate positioning with electric actuators

In 1972, Hermann Painter surprised, thrilled and amazed the professional world with his first self-propelled sugar-beet harvester. Armed with his ideas, inventiveness and resolve, he went on to found the company ROPA.

Today, the company is located in Lower Bavaria and now sells more than just harvesters and cleaning loaders for sugar beets. For several years now, ROPA has been focusing on the potato market.
By developing the two-row trailed potato harvester, Keiler (wild boar) II, ROPA has remained true to its corporate philosophy and has broken new grounds.

The degree of automation in this machine is, by comparison to other machines, extremely high. Alongside the numerous hydraulic options, such as the automatic axle displacement or the automatic ridge pressure regulation, electric linear actuators handle tasks such as adjusting deflection rollers, finger combs and pintle belts. Seven LINAK electric linear actuators ensure precise movement for the harvester.

The engineers from ROPA designed the machine from scratch. It is probably unique in having this number of adjustment options to optimise the harvesting process. Regardless of the power take-off rotation speed, many elements can be adjusted hydraulically. In applications where high positioning accuracy is a must, electric actuators are used over hydraulic cylinders.

“It is especially in those adjustments where you have to set a very fine dosage, such as adjusting deflection rolls or in transition areas of cleaning elements, that we chose to use electric actuators,” explains Dr. Rupert Geischeder, an experienced division manager, responsible for the entire potato harvester product range.

ROPA potato harvesters with LINAK actuatorsLINAK electric actuators are used to position multiple cleaning elements and deflection rolls.
 

For this application area, ROPA only uses the LINAK LA36 actuator. They are known for their strength, robustness, and their various control options. One of these precise positioning adjustments is down to the pintle belts. The pintle belts remove the soil from the harvested potatoes. The accurate electrical positioning of the pintle belts makes the harvesting process simple and comfortable via a touch panel.

The staff working on the potato harvester is not only able to adjust the pintle belts electrically, but also other cleaning elements as well. Thanks to the infinite step-free positioning options, the resistance paddles needed to remove the greens can be adjusted, so that even when the potato greens are lush, the crop loss is kept to a minimum.

Dirt, dust, water and varying temperatures - the electric actuator has to function properly despite these harsh environments. Downtime during the harvest season would have severe financial consequences for the farmer.

 “LINAK sets the benchmark in terms of robustness of electric variable actuators”, explains Dr. Rupert Geischeder.

In fact, use in hostile environments was a core priority for the Danish manufacturer when developing the linear actuator LA36. The LA36 fulfils protection class IP66 in a dynamic state and IP69K in a static state.

“The actuator is already being used in many applications in the agricultural market, and has therefore proven itself,” says Günther Rappl, LINAK sales manager for Bavaria.

ROPA potato harvesters with LINAK actuatorsThe linear actuator LA36
 

The linear actuator LA36 is not the only LINAK actuator to meet these high protection classes. A further special feature of the ROPA potato harvester is the control of the actuator. The replacement of a hydraulic cylinder with an electric actuator should be as simple as possible. This also applies to the computer output capacity.

“We had to meet certain requirements for this application, and we have done this, together with LINAK”, says Dr. Rupert Geischeder.

The keyword is pin control. Because of the complexity of the machine, the outputs of the control boxes were for the most part occupied. It therefore had to be possible to control the actuator, so running out/running in, with a single wire control.

“We have developed a custom software that makes the single wire control possible,” explains Günther Rappl. ”This makes it possible to control the electric actuator like a hydraulic cylinder.”

 

Electricity replaces hydraulics

As well as robustness and customised control, electric actuators offer additional advantages. For example, the weight plays an increasingly important role. When implementing a movement system in such a large machine, the electric solution saves valuable weight compared to a hydraulic system. Electric actuators also receive a high score in the area of maintenance-free systems. It was not only the positive attributes of an electric actuator that convinced ROPA, but also the close cooperation with the product developers at LINAK.

“We decided to use LINAK actuators, because we have a high degree of trust in the robustness of the product and also in LINAK‘s experience with agricultural machinery movement,“ he concludes.

ROPA potato harvesters with LINAK actuatorsDr. Rupert Geischeder is responsible for the entire potato harvester product range
 
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Electric linear actuator solutions for agricultural machinery from the LINAK TECHLINE segment

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