1. bookVolume 72 (2022): Issue 3 (September 2022)
Journal Details
License
Format
Journal
eISSN
2719-5430
First Published
30 Mar 2016
Publication timeframe
4 times per year
Languages
English
access type Open Access

Draft force reduction by an electrification unit on implements

Published Online: 23 Jun 2022
Volume & Issue: Volume 72 (2022) - Issue 3 (September 2022)
Page range: 105 - 111
Received: 27 Jul 2021
Accepted: 07 Dec 2021
Journal Details
License
Format
Journal
eISSN
2719-5430
First Published
30 Mar 2016
Publication timeframe
4 times per year
Languages
English
Summary

Electrification is done in newer tractors hesitantly. There will be an increase in the need for electrified mounted implements and application units. Semi-liquid manure and degestate from biogas crops are increasingly injected directly into the soil. This technique reduces nutrient losses and ammonia emissions. In the case of loamy soils and clay, a high draft force is needed for slurry deposition into the soil. With the development and testing of an application unit with reduced working width of 3 m, the draft force reduction was found to be lower by nearly one third. The field trials have been performed in two steps: first, a prototype with spiked roller and star packer as a traction element on the roller unit in 3-m working width and second, a final slurry grubber with 6-m working width and cutting coulter on the traction roller. We tested both devices with and without powering the electrified traction roller. These field tests took place on six fields near Freising in Germany. Results showed that firstly, draft force reduction up to 35% was achieved with a powered traction roller on the mounted implement having 20% slippage on the traction roller. These values were obtained by pulling a tractor with the electrified implement by another tractor in a horizontal ground level. Second, we observed a different variation range of the values among the three test fields. This results from differences in the soil structure on the test fields having pebbles and stones near the soil surface or bigger stones down the working depth of 22.5 cm. The presented results show new kinds of working scenarios and operation modes for agriculture. Electrification can be an advantage in taking care of nutrient losses and ammonia emissions as it leads to a draft force reduction on heavy soils.

Keywords

Schlagwörter

Introduction

Electrification has high potential efficiency in agriculture (Aumer, 2008). The faster the tractor manufacturers apply this new technology, the faster attachment with this technology will be required. Big players like John Deere tend to show more tractors that are electric on exhibitions in the future (Koerhuis and van Hattum, 2020). As Renius (1994) mentioned, tractors’ weight should be as low as possible. Putting a part of the electrification components on the implement seems to be a proper solution. Several research groups are working on electrification of field work. Global player companies in electrification focus on electrification in agriculture (ZF 2019). Our study shows the possible application scenario based on an electrified slurry grubber, similar to the implements of Vogelsang (2020). For this purpose, we did extensive field tests, which were carried out both with and without electrical support from the attachment. In contrast to Wiecha et al. (2019), we compare the results of three different fields in two test seasons.

For tilling loamy soils and clay, a high draft force is needed by the tractor, as presented in the study of Ranjbarian et al. (2017) for different implements. Slurry penetration into loamy soils and clay is a new kind of work mode. The goal of this method is to prevent nutrition losses and emissions. Focusing on so-called strip-till implements, it is unusual to use them on heavy field conditions because of the pulling force needed. With the help of a traction roller built in front of the slurry grubber, the implements become their own traction unit, reducing the hole traction force needed for the tractor. New working scenarios on heavy soils with a high potential for reducing emissions will become realistic and applicable if this study is able to show a significant draft force reduction with the use of an electrified traction roller.

Materials and methods
Constructive elements of the prototype

In all field trials and construction of the electrified slurry grubber, we followed the work of Wiecha et al. (2019b). The slurry-injecting prototype was designed with a traction roller and a continuous traction element. The traction elements were star packers. Because of its weight, we constructed the roller near the mounting of the implement. A set of seven furrow grubbers with slurry-injecting application unit was mounted to the following frame before recompacting the soil with a closing unit.

In accordance with Lindner et al. (2011), a generator mounted to the front power take-off (front p.t.o.) of the tractor was used for generating a voltage of 650 V. An inverter regulated this voltage to the needs of the ZF electric motor, which had the technical specifications of a maximum of 400 V, 230 A, 125 kW, and up to 10300 rpm with a gear ratio of 35.84. A radar sensor manufactured by DICKEY corporation model 4282089M2 measured the speed over ground. We calculated the rotation speed of the traction roller at every moment of driving from the values taken from the radar sensor. System control was done by the steering software on a laptop. The software package was ControlDesk 6.2 by dSPACE-embedded systems. The rotation speed was set to 20% slippage on the traction roller through ControlDesk software. The draft force sensor was manufactured with draft force cell “HBM U1” by Ingenieurbüro Rottmaier in Erding, Germany and had a draft force limitation to 200 kN. It had a working load of 240 kN and a compound error of <±0.03% from the final value (reference temperature was 23°C). The logging speed was set to 10 values per second for the draft force sensor and the radar sensor.

Figure 1 shows the setup of one of the field trials.

The setup of the measuring unit on the field. The prototype has 3-m working width.

Abbildung 1. Die Konfiguration der Feldversuche. Der Prototyp hat 3 m Arbeitsbreite.

In Figure 1, from right to left, we see Fendt 818 (old type) with an additional front ballast of 1.2 t for better pulling. Afterward, the draft force unit was tied together with loops to the second Fendt Vario 818 (newer type). On the second Fendt to the front PTO, we placed the electric generator. The second tractor carried electrified slurry grubber.

Under very dry conditions between March and May 2019, three fields with heavy soil types were identified for receiving clear data in the draft force trials. The size of the fields near Freising in Germany ranged from 3 to 12 ha. With the soil types D = soil on Pleistocene sediments, L = loam, and SL = sandy loam, the fields are located under the following global positioning system coordinates:

– Field 1: 48°25′45.5″N 11°40′16.2″E; L4D, 59/52 (land value)

– Field 2: 48°24′02.1″N 11°42′40.5″E; L4D, 65/61

– Field 3: 48°25′27.6″N 11°40′00.2″E; SL4D, 50/46

On every field, the area of plane ground was used for driving. Drive speed was set to 8 km h−1 in all field trials in this study. In the data, we used a single driving lane with and without electrification near one another in the same direction of every field. Data logging started on reaching a speed of 8 km h−1 and stopped at the moment the speed was reduced. We drove the whole lane with this speed until the end of the field. Turns and stops were not included in the results.

Speeding up between 1 and 8 km h−1 was also discarded as changes of slope. The data were tracked in LabView software 2016 using an NI-USB 6001. All seven furrow grubbers were adjusted to a working depth of 22.5 cm. The depth was manually checked by hand before starting to drive. The slippage on the traction roller was set to 20%.

Constructive elements of the final implement

The final slurry grubber was designed to meet the case of cultivating maize in 75-cm row spaces. On the traction roller, a rotating coulter was mounted for cutting the upper soil layer in front of each single grubber furrow. Now, steering software was implemented in the ISOBUS terminal. An identical slippage of 20% on the traction roller was adjusted by using the terminal. In contrary to the prototype, two electric motors from NIDEC type PEV50-8-D011, one on each side of the implement, were used. With a voltage of 540 V DC, the motor was able to reach a peak power of 85 kW, a maximum torque of 320 N m, and a rotation speed of up to 6000 rpm. Figure 2 shows the setup on the field with the final implement. As described before, the sensor manufactured by DICKEY corporation model 4282089M2 and the draft force unit of Ingenieurbüro Rottmair (Erding, Germany) were used during the tests with the final implement.

The setup on the field with the final implement with 6-m working width.

Abbildung 2. Die Konfiguration der Feldversuche mit dem finalen Demonstrator in 6 m Arbeitsbreite.

The pulling tractor was a Claas Axion 870 with mounted draft force measuring unit, followed by the Fendt 818 Vario with front PTO generator and the mounted implement with 6-m working width (Figure 2). The fields with their soil types were located under the following coordinates:

– Field 4: 48°25′26.1″N 11°40′00.3″E; SL4D, 50/46

– Field 5: 48°24′02.1″N 11°42′40.5″E; L4D, 65/61

– Field 6: 48°25′43.1″N 11°40′10.7″E; L4D, 63/55

Conditions on the fields between February and April 2021 were humid in the early spring. The decision for using the fields and the driving area within the fields was made by the factor of driveability. On the fields 4–6, identical preceding crop and intercrop was ensured. As in the case of fields 1–3 from prototype tests, all fields were untilled before. Logging the data was done by LabView 2016 and the NI-USB 6001 box. Frequency of logging and description of cutting the data in the point of driving speed were also identical to the prototype test in 2019.

Statistical test

For the field tests in 2019 and 2021, we used the Welch’s t-test performed in R (R Core Team 2014). This test is used to find the means of two independent data groups. In our case, one group of data represents the draft force values without electrification and the second group of data represents the values with electrification.

Results and Discussion
Values received for all tests

From the six fields, we received totally N = 6521 draft force values. In Table 1 are shown the values per field, with and without electrification. The number of values per field depends on the length of the driving lanes during the field trials. With the final implement, the space requirement of turning around the field with two tractors tied together is bigger. Due to this, the n-values of these trials are lesser.

n values of traction force received per field

Tabelle 1: Erzielte Anzahl an Zugkraftwerten für jedes Versuchsfeld

Field and setupn
Prototype, 3-m working width
Field 1 without electrification635
Field 1 with electrification473
Field 2 without electrification296
Field 2 with electrification495
Field 3 without electrification1468
Field 3 with electrification1178

Final implement, 6-m working width
Field 4 without electrification600
Field 4 with electrification360
Field 5 without electrification140
Field 5 with electrification137
Field 6 without electrification379
Field 6 with electrification360

Total6521
Results of the prototype tests

Figure 3 shows that in all three cases, the draft force reduction between the left boxplot with no electrification and the right boxplot with electrification is significant. Fields 1 and 2 show a higher variation of values under electrification, which was not expected. With an electrification assistance, a smoother run of the implement was anticipated. The next step is to evaluate the significance by Welch’s two-sample t-test using R software for each field.

Boxplot of the draft force reduction with the prototype on three fields. n. e. = with no electrification, e. = with electrification

Abbildung 3. Boxplot der Zugkraftreduzierung mit dem Prototyp auf drei Feldern, n. e. = nicht elektrifiziert, e. = elektrifiziert

Table 2 shows the output of every t-test done separately for every field. In all three cases, the p-value is lower than 0.05, which shows significance. Obviously, there is no explanation for the broader variance under electrification. One reason could be that the test vehicle naturally has additional sensors installed on the traction roller and the traction roller is, therefore, more flexibly mounted in order to deliver values during measuring. The measured values from the traction roller itself are not included in this investigation, as the traction force savings of the overall tractor–implement setup have to be shown. Table 3 presents the draft force consumption of the first prototype.

Summary of the three t-tests of the electrified and non-electrified value groups

Tabelle 2. Zusammenfassung von drei T-Tests der elektrifizierten und nicht-elektrifizierten Wertegruppen

tdfp
Field 125.074632.97<2.2e-16
Field 233.341774.15<2.2e-16
Field 367.5962132.00<2.2e-16
Results of the final implement test with 6-m working width

As seen in Figure 4, in the case of field 4 and field 6, the draft force reduction is clearly measurable. Regarding the middle of Figure 4, field 5 seems to be different. The received values of field 5 are close to each other and show a draft force reduction of nearly 5%. Looking at the field itself, the soil type is less heavy and dries faster during spring because of strong wind blowing in a largely free and exposed location. After laying down the heavy implement on the soil surface, the soil seemed to smear under the pressure of the rotating roller. Due to a long period of humidity, no better conditions could be used for this field during the tests. Again, two-sample t-test is used for verifying the data. The results are presented in Table 4.

Results of the final implement with 6-m working width. n. e. = with no electrification, e. = with electrification

Abbildung 4. Ergebnisse mit dem finale Anbaugerät in 6 m Arbeitsbreite, n. e. = nicht elektrifiziert, e. = elektrifiziert

On comparing Tables 3 and 5, it is observed that the received draft force reduction is smaller with the final implement than with the early prototype. This may be due to several reasons. First, the area of traction symbolized by the contact surface between soil and the roller is relatively big. The final implement with its 6-m working width has to pull eight grubber furrows (the prototype with its 3-m working width carried seven grubber furrows). Therefore, the draft force consumption by the final implement could be smaller.

Draft force consumption of the prototype with 3-m working width

Tabelle 3. Zugkrafteinsparung mit dem Prototyp in 3 m Arbeitsbreite

Mean without electrification (kN)Mean with electrification (kN)Saving in kNPercent of reduction
Field 151.1939.8211.3722.21
Field 238.3527.5510.8028.16
Field 341.6327.0314.6035.07

Summary of the three t-tests of the electrified and non-electrified value groups with the final implement

Tabelle 4. Zusammenfassung von drei T-Tests der elektrifizierten und nicht-elektrifizierten Wertegruppen des finale Anbaugerätes

tdfp
Field 456.703926.28<2.2e-16
Field 56.0096271.275.973e-09
Field 624.84733.34<2.2e-16

Draft force consumption of the final implement with 6-m working width

Tabelle 5. Zugkrafteinsparung mit dem finale Anbaugerät mit 6 m Arbeitsbreite

Mean without electrification (kN)Mean with electrification (kN)Saving in kNPercent of reduction
Field 440.9332.928.0119.57
Field 536.3434.591.754.82
Field 640.2332.817.4218.44

Second, the traction elements on the prototype roller were designed to have a good formfit with the soil for perfect transfer of the traction force. In contrast, the coulter element on the electrified roller of the final implement was designed to cut into the soil for making an easier way for the following grubber furrows. The aim was to reduce the draft force not only through traction, but also through opening the soil before.

Third reason could be the amount of metal penetrating the soil and the amount of metal laying on top of the soil. Elements of flat metal rotating on the soil surface do not transfer traction. Only the traction elements that go down into the soil transport the soil to the rear. In case of the final implement, only a few centimeters of metal are intruding the soil. Therefore, traction support could not be as good as on the traction roller of the first prototype.

Conclusions

The present study on electrified implements mounted on farm equipment shows a clear outcome in draft force reduction. The statistical significance is demonstrated on six fields and in 2 years with extremely different weather and soil conditions. As a result, strip-till implements can be built now with traction support for working scenarios on heavy soils. With a focus on traction transfer, we achieved up to 35% draft force reduction. Making an implement with the focus being on cutting into the soil, we achieved nearly 20% draft force reduction. At the moment, tractor manufactures have not fully decided about using built-in electrical generators on their tractors. The heavy weight pressing down the soil surface and the high construction costs should also be considered. This slows down the acceptance of such devices on the market.

On comparing the study of Ranjbarian et al. (2017) and the results of our work, it is found that the weather and climate conditions of every single field seem to have an impact on draft force reduction. Even a windy weather for a couple of days before the field test might change the conditions of the upper soil layer, and therefore the conditions for traction with the roller. This opens up a wide range of influencing factors, which results in a need for much more driving tests for the attachment.

Figure 1

The setup of the measuring unit on the field. The prototype has 3-m working width.Abbildung 1. Die Konfiguration der Feldversuche. Der Prototyp hat 3 m Arbeitsbreite.
The setup of the measuring unit on the field. The prototype has 3-m working width.Abbildung 1. Die Konfiguration der Feldversuche. Der Prototyp hat 3 m Arbeitsbreite.

Figure 2

The setup on the field with the final implement with 6-m working width.Abbildung 2. Die Konfiguration der Feldversuche mit dem finalen Demonstrator in 6 m Arbeitsbreite.
The setup on the field with the final implement with 6-m working width.Abbildung 2. Die Konfiguration der Feldversuche mit dem finalen Demonstrator in 6 m Arbeitsbreite.

Figure 3

Boxplot of the draft force reduction with the prototype on three fields. n. e. = with no electrification, e. = with electrificationAbbildung 3. Boxplot der Zugkraftreduzierung mit dem Prototyp auf drei Feldern, n. e. = nicht elektrifiziert, e. = elektrifiziert
Boxplot of the draft force reduction with the prototype on three fields. n. e. = with no electrification, e. = with electrificationAbbildung 3. Boxplot der Zugkraftreduzierung mit dem Prototyp auf drei Feldern, n. e. = nicht elektrifiziert, e. = elektrifiziert

Figure 4

Results of the final implement with 6-m working width. n. e. = with no electrification, e. = with electrificationAbbildung 4. Ergebnisse mit dem finale Anbaugerät in 6 m Arbeitsbreite, n. e. = nicht elektrifiziert, e. = elektrifiziert
Results of the final implement with 6-m working width. n. e. = with no electrification, e. = with electrificationAbbildung 4. Ergebnisse mit dem finale Anbaugerät in 6 m Arbeitsbreite, n. e. = nicht elektrifiziert, e. = elektrifiziert

Figure 1

The setup of the measuring unit on the field. The prototype has 3-m working width.Abbildung 1. Die Konfiguration der Feldversuche. Der Prototyp hat 3 m Arbeitsbreite.
The setup of the measuring unit on the field. The prototype has 3-m working width.Abbildung 1. Die Konfiguration der Feldversuche. Der Prototyp hat 3 m Arbeitsbreite.

Figure 2

The setup on the field with the final implement with 6-m working width.Abbildung 2. Die Konfiguration der Feldversuche mit dem finalen Demonstrator in 6 m Arbeitsbreite.
The setup on the field with the final implement with 6-m working width.Abbildung 2. Die Konfiguration der Feldversuche mit dem finalen Demonstrator in 6 m Arbeitsbreite.

Figure 3

Boxplot of the draft force reduction with the prototype on three fields. n. e. = with no electrification, e. = with electrificationAbbildung 3. Boxplot der Zugkraftreduzierung mit dem Prototyp auf drei Feldern, n. e. = nicht elektrifiziert, e. = elektrifiziert
Boxplot of the draft force reduction with the prototype on three fields. n. e. = with no electrification, e. = with electrificationAbbildung 3. Boxplot der Zugkraftreduzierung mit dem Prototyp auf drei Feldern, n. e. = nicht elektrifiziert, e. = elektrifiziert

Figure 4

Results of the final implement with 6-m working width. n. e. = with no electrification, e. = with electrificationAbbildung 4. Ergebnisse mit dem finale Anbaugerät in 6 m Arbeitsbreite, n. e. = nicht elektrifiziert, e. = elektrifiziert
Results of the final implement with 6-m working width. n. e. = with no electrification, e. = with electrificationAbbildung 4. Ergebnisse mit dem finale Anbaugerät in 6 m Arbeitsbreite, n. e. = nicht elektrifiziert, e. = elektrifiziert

Figure 1

The setup of the measuring unit on the field. The prototype has 3-m working width.Abbildung 1. Die Konfiguration der Feldversuche. Der Prototyp hat 3 m Arbeitsbreite.
The setup of the measuring unit on the field. The prototype has 3-m working width.Abbildung 1. Die Konfiguration der Feldversuche. Der Prototyp hat 3 m Arbeitsbreite.

Figure 2

The setup on the field with the final implement with 6-m working width.Abbildung 2. Die Konfiguration der Feldversuche mit dem finalen Demonstrator in 6 m Arbeitsbreite.
The setup on the field with the final implement with 6-m working width.Abbildung 2. Die Konfiguration der Feldversuche mit dem finalen Demonstrator in 6 m Arbeitsbreite.

Figure 3

Boxplot of the draft force reduction with the prototype on three fields. n. e. = with no electrification, e. = with electrificationAbbildung 3. Boxplot der Zugkraftreduzierung mit dem Prototyp auf drei Feldern, n. e. = nicht elektrifiziert, e. = elektrifiziert
Boxplot of the draft force reduction with the prototype on three fields. n. e. = with no electrification, e. = with electrificationAbbildung 3. Boxplot der Zugkraftreduzierung mit dem Prototyp auf drei Feldern, n. e. = nicht elektrifiziert, e. = elektrifiziert

Figure 4

Results of the final implement with 6-m working width. n. e. = with no electrification, e. = with electrificationAbbildung 4. Ergebnisse mit dem finale Anbaugerät in 6 m Arbeitsbreite, n. e. = nicht elektrifiziert, e. = elektrifiziert
Results of the final implement with 6-m working width. n. e. = with no electrification, e. = with electrificationAbbildung 4. Ergebnisse mit dem finale Anbaugerät in 6 m Arbeitsbreite, n. e. = nicht elektrifiziert, e. = elektrifiziert

Summary of the three t-tests of the electrified and non-electrified value groupsTabelle 2. Zusammenfassung von drei T-Tests der elektrifizierten und nicht-elektrifizierten Wertegruppen

tdfp
Field 125.074632.97<2.2e-16
Field 233.341774.15<2.2e-16
Field 367.5962132.00<2.2e-16

Draft force consumption of the prototype with 3-m working widthTabelle 3. Zugkrafteinsparung mit dem Prototyp in 3 m Arbeitsbreite

Mean without electrification (kN)Mean with electrification (kN)Saving in kNPercent of reduction
Field 151.1939.8211.3722.21
Field 238.3527.5510.8028.16
Field 341.6327.0314.6035.07

Draft force consumption of the final implement with 6-m working widthTabelle 5. Zugkrafteinsparung mit dem finale Anbaugerät mit 6 m Arbeitsbreite

Mean without electrification (kN)Mean with electrification (kN)Saving in kNPercent of reduction
Field 440.9332.928.0119.57
Field 536.3434.591.754.82
Field 640.2332.817.4218.44

n values of traction force received per fieldTabelle 1: Erzielte Anzahl an Zugkraftwerten für jedes Versuchsfeld

Field and setupn
Prototype, 3-m working width
Field 1 without electrification635
Field 1 with electrification473
Field 2 without electrification296
Field 2 with electrification495
Field 3 without electrification1468
Field 3 with electrification1178

Final implement, 6-m working width
Field 4 without electrification600
Field 4 with electrification360
Field 5 without electrification140
Field 5 with electrification137
Field 6 without electrification379
Field 6 with electrification360

Total6521

Summary of the three t-tests of the electrified and non-electrified value groups with the final implementTabelle 4. Zusammenfassung von drei T-Tests der elektrifizierten und nicht-elektrifizierten Wertegruppen des finale Anbaugerätes

tdfp
Field 456.703926.28<2.2e-16
Field 56.0096271.275.973e-09
Field 624.84733.34<2.2e-16

Aumer, W., Lindner, M., Geißler, M. and Th. Herlitzius (2008): Elekrischer Traktor: Vision oder Zukunft? Landtechnik 63, 14–15.AumerW.LindnerM.GeißlerM.HerlitziusTh.2008Elekrischer Traktor: Vision oder Zukunft?Landtechnik631415Search in Google Scholar

Koerhuis, R. and B. van Hattum (2020): John Deere: ‘We believe in electric tractors. 100%’. In: Future Farming, Machinery Background, 12.03.2020. Available under: https://www.futurefarming.com/Machinery/Articles/2020/3/John-Deere-We-believe-in-electric-tractors-100-552869E/, last checked 10.10.2020.KoerhuisR.van HattumB.2020John Deere: ‘We believe in electric tractors. 100%’In: Future Farming, Machinery Background, 12.03.2020. Available under: https://www.futurefarming.com/Machinery/Articles/2020/3/John-Deere-We-believe-in-electric-tractors-100-552869E/, last checked 10.10.2020.Search in Google Scholar

Lindner, M., Aumer, W., Geißler, M. and Th. Herlitzius (2011): Herausforderungen bei der Elektrifizierung von Geräten in der Landwirtschaft. In: Hybridantriebe für mobile Arbeitsmaschinen: 3. Fachtagung, 17. Februar 2011, 107–116.LindnerM.AumerW.GeißlerM.HerlitziusTh.2011Herausforderungen bei der Elektrifizierung von Geräten in der LandwirtschaftIn:Hybridantriebe für mobile Arbeitsmaschinen: 3. Fachtagung17. Februar 2011107116Search in Google Scholar

Murugan, R., Koch, H. J. and R. G. Joergensen (2014): Long-term influence of different tillage intensities on soil microbial biomass, residues and community structure at different depths. Biology and Fertility of Soils 50–3, 487–498.MuruganR.KochH. J.JoergensenR. G.2014Long-term influence of different tillage intensities on soil microbial biomass, residues and community structure at different depthsBiology and Fertility of Soils50–348749810.1007/s00374-013-0871-xSearch in Google Scholar

R Core Team (2014): R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. Available under: http://www.R-project.org/R Core Team2014R: A language and environment for statistical computingR Foundation for Statistical ComputingVienna, AustriaAvailable under: http://www.R-project.org/Search in Google Scholar

Ranjbarian, S., Askari, M. and J. Jannatkhah (2017): Performance of tractor and tillage implements in clay soil. Journal of the Saudi Society of Agricultural Sciences 16, 154–162.RanjbarianS.AskariM.JannatkhahJ.2017Performance of tractor and tillage implements in clay soilJournal of the Saudi Society of Agricultural Sciences1615416210.1016/j.jssas.2015.05.003Search in Google Scholar

Renius, K. (1994): Trends in Tractor Design with Particular Reference to Europe. Institute of Agricultural Machinery. Journal of Agricultural Engineering Research 57, 3–22.ReniusK.1994Trends in Tractor Design with Particular Reference to Europe. Institute of Agricultural MachineryJournal of Agricultural Engineering Research5732210.1006/jaer.1994.1002Search in Google Scholar

Vogelsang GmbH & Co. KG (2020): Fortschrittliche Strip Till-Technik. Available under https://www.vogelsang.info/index.php?eID=dumpFile&t=f&f=2844&token=7130bfbb7c8f7a101573d0a3206fd6bb206ddbaa, last checked 10.10.2020.Vogelsang GmbH & Co. KG2020Fortschrittliche Strip Till-TechnikAvailable under https://www.vogelsang.info/index.php?eID=dumpFile&t=f&f=2844&token=7130bfbb7c8f7a101573d0a3206fd6bb206ddbaa, last checked 10.10.2020.Search in Google Scholar

Wiecha, J. G., Bernhardt, H., Bögel, T. and Th. Herlitzius (2019a): Reducing draft force on mounted implements by an electrified traction roller – Traction assistance on a slurry-injecting grubber. In: LAND.TECHNIK AgEng 2019 – The Forum for Agricultural Engineering Innovations. Düsseldorf: VDI Verlag 2019, 495–502.WiechaJ. G.BernhardtH.BögelT.HerlitziusTh.2019aReducing draft force on mounted implements by an electrified traction roller – Traction assistance on a slurry-injecting grubberIn:LAND.TECHNIK AgEng 2019 – The Forum for Agricultural Engineering InnovationsDüsseldorfVDI Verlag2019,49550210.51202/9783181023617-495Search in Google Scholar

Wiecha, J. G., Bögel, T., Herlitzius, Th. and H. Bernhardt (2019b): Electrification of Mounted Implements – Conceps of Traction Assistance. In: Proceedings of the 47th Symposium “Actual Tasks on Agricultural Engineering”, University of Zagreb, Croatia, 51–60WiechaJ. G.BögelT.HerlitziusTh.BernhardtH.2019bElectrification of Mounted Implements – Conceps of Traction AssistanceIn:Proceedings of the 47th Symposium “Actual Tasks on Agricultural Engineering”University of Zagreb, Croatia5160Search in Google Scholar

ZF Friedrichshafen AG (2019): The Future of Farming. Available under https://www.zf.com/products/media/industrial/agriculture/downloads_3/Agritechnica_Vademecum_2019_Screen.pdf.ZF Friedrichshafen AG2019The Future of FarmingAvailable under https://www.zf.com/products/media/industrial/agriculture/downloads_3/Agritechnica_Vademecum_2019_Screen.pdf.Search in Google Scholar

Recommended articles from Trend MD

Plan your remote conference with Sciendo