Fakultät Agrarwissenschaften

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Die Fakultät entwickelt in Lehre und Forschung nachhaltige Produktionstechniken der Agrar- und Ernährungswirtschaft. Sie erarbeitet Beiträge für den ländlichen Raum und zum Verbraucher-, Tier- und Umweltschutz.

Homepage: https://agrar.uni-hohenheim.de/

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Die Abscheidefunktion von Hordenschüttler und Reinigungsanlage in Mähdreschern
(1993) Böttinger, Stefan
Das Durchsatzoptimum von Mähdreschern wird bei dem maximalen Gutdurchsatz mit noch akzeptablen Kornverlusten der Trennelemente Hordenschüttler und Reinigungsanlage erreicht. Dem Mähdrescher-Fahrer müssen Hilfsmittel für das Erkennen des Durchsatzoptimums zur Verfügung gestellt werden, da es in Abhängigkeit der Stoffeigenschaften des Erntegutes stark schwankt. Es werden physikalische Modelle für die Trennprozesse im Mähdrescher aufgestellt und die mathematische Beschreibung der Kornabscheidung über der Länge der Trennelemente daraus abgeleitet. Aus Messwerten der Kornabscheidung an verschiedenen Stellen eines Trennelementes werde aktuelle Parameter der Abscheidefunktion bestimmt und verschiedenen Prozesskenngrößen berechnet. Die Korrelation zwischen den berechneten Prozesskenngrößen und dem Betriebsverhalten der Trennelemente wird im labor- und Feldversuch experimentell untersucht.
Adaptive operator systems in tractors
analysis of potentials and methods for specification and evaluation
(2024) Schempp, Timo Thomas
Der Ackerschlepper wird in der Landwirtschaft, auf dem Bau, im Forst und im Kommunalbereich als Universalmaschine eingesetzt. Dazu wird er wechselnd mit einer Vielzahl von Maschinen gekoppelt, um diese zu betreiben. Es ergeben sich wechselnde Bedienszenarien mit unterschiedlichen Anforderungen an die Bedienung der gekoppelten Maschinen. Heutige Bediensysteme sind statisch und müssen daher als Kompromisslösung für diese unterschiedlichen Anforderungen an die Bedienung eingeordnet werden. Adaptive Bediensysteme können sich hingegen an wechselnde Bedienszenarien anpassen. Diese Arbeit beleuchtet den Stand der Technik der Bediensysteme in Ackerschleppern allgemein und explizit an drei ausgewählten Beispielen. Ferner werden zwei Methoden beschrieben, mit denen ein adaptives Bediensystem spezifiziert werden kann. Für die Bewertung der kognitiven und physischen Ergonomie von Bediensystemen allgemein werden zwei weitere Methoden vorgestellt. Alle Methoden sind für einen auf dem V-Modell basierenden Entwicklungsprozess geeignet. Die beschriebenen Ergebnisse einer theoretischen und praktischen Potentialanalyse motivieren den Einsatz adaptiver Bediensysteme im Ackerschlepper. Die theoretische Potentialanalyse stützt sich auf die Grundlagen der Ergonomie und auf die Art und Weise wie die Funktionen in einem Ackerschlepper genutzt werden. Die praktische Potentialanalyse stützt sich auf die Auswertung und Analyse von Messdaten aus dem Feld mit fast 500 Arbeitsstunden aus 14 Bedienszenarien. Ferner beschreibt diese Arbeit die Anwendung der Methoden zur Spezifikation, das entwickelte und funktionsfähige adaptive Bediensystem und die Anwendung der Bewertungsmethoden, die für das adaptive Bediensystem eine signifikante Verbesserungen der physischen und kognitiven Ergonomie zeigen.
Agrarlexikon mit den wichtigsten Begriffen zur Landwirtschaft im europäischen Umfeld
Bedeutung in deutscher und englischer Sprache erklärt
(2017) Hartmann, Peter; Raupp, Manfred G.
Agriculture in responsibility for our common world
(2022) Raupp, Manfred G.; Thomas, Angelika; Schüle, Heinrich; Carabet, Alin Flavius; Salasan, Cosmin; Fora, Ciprian George; Weinmann, Markus; Madora GmbH; University of Hohenheim, Institute of Crop Science; Klara Bradacova
The vocational training course program “Agriculture in Responsibility for our common World” organised within the frame of the Banat Green Deal Project “GreenERDE” (Education and Research in the context of the digital and ecological transformation of agriculture in the Banat Region and Baden-Württemberg - towards resource efficiency and resilience) and delivered between June 2021 and May 2022 targets the knowledge and experience transfer to the farmer community in the Banat Region, Romania and other parts of the world. Current and future challenges, such as the ecological conversion and digital transformation of agricultural production, but also social, economic and cultural aspects haven been addressed transcending prevailing patterns. The innovative and relevant knowledge originating from practice, experiments, research or development projects throughout Europe and other continents is presented in a training format for interested participants.
Anforderungs- und einsatzgerechte Auslegung von Fahrantrieben mobiler Erntemaschinen
(2019) Häberle, Steffen
Fahrantriebe mobiler Erntemaschinen werden im Rahmen einer fortschreitenden Automatisierung zunehmend zum integralen Bestandteil der Prozessführung. Komplexe Anforderungen, die sich aus deren Einsatz ergeben, haben zu einer Etablierung hydrostatischer Fahrantriebe geführt. Der zunehmende legislative Druck und die steigenden Vermarktungschancen kraftstoffsparender Technologien rücken die Effizienzbewertung von Antriebssystemen stärker in den Fokus der Forschung und Entwicklung. Standardisierte Bewertungssysteme lassen sich bei mobilen Arbeitsmaschinen, wegen deren Heterogenität und Vielfältigkeit ihrer Aufgaben, allerdings nur schwer umsetzen. Die vorliegende Arbeit zeigt einen allgemeingültigen methodischen Ansatz zur Effizienzbewertung anhand von Lastkollektiven und eines Simulationsmodells auf. Dieser lässt sich auf alle mobilen Arbeitsmaschinen mit quasistationären Lastanteilen anwenden. Am Beispiel eines Mähdreschers werden typische Einsatzbedingungen mit gemessenen Einsatzprofilen und Lastkollektiven ermittelt und in den Gesamtkontext möglicher Nutzungsszenarien kategorisiert. Mittels eines Antriebsstrangmodells wird damit die Energieausnutzung des Fahrantriebs, entsprechend den Einsatzbedingungen, berechnet. Basierend auf diesen Ergebnissen und einer detaillierten Anforderungsanalyse sind neue Antriebslösungen erarbeitet und entsprechenden Leistungsklassen zugeordnet worden. Für einen Referenzmähdrescher wird ein methodisch ausgewähltes Fahrantriebskonzept, ein sogenannter Summierungsantrieb, ausgelegt und modellbasiert bewertet. Die berechneten Ergebnisse der optimierten Antriebsvariante zeigen deutliche Verbesserungen der Energieausnutzung bei einem erhöhten Kundennutzen.
Behavioral economic impact on animal health surveillance system in Thailand (correct version of the dissertation)
(2021) Kewprasopsak, Tossapond
Zoonotic diseases are a continuously significant threat to global human and livestock health (causing millions of deaths yearly). Zoonotic diseases are not only a human health threat, but also a threat to animal health and welfare. Moreover, they have a high impact on national economies and food security due to productivity and production reduction. Expanding worldwide travel and global trade increases the importance of the threat of zoonotic diseases. The increase in global meat consumption contrasts with the escalating instability of the global meat market, which is affected by the increase of livestock densities, changes in production intensity, and slaughtering systems, causing animal disease outbreaks to spread widely. This study focuses on the animal disease surveillance system in Thailand as an important world meat exporter. In 2014, the Participatory One Health Disease Detection project, or PODD was set up by the veterinary inspection authorities to test animal epidemic control systems using smartphone applications in the Chiang Mai province in northern Thailand The main objectives of this study are (i) to evaluate the economic impact of the PODD system on farmers by impact assessment (n = 177) (ii) to demonstrate the impact of monetary and non-monetary incentives on the PODD reporters by the experimental approach (n = 17), (iii) and to present the effect of the socioeconomic factors and behavioral bias on farmers animal disease reporting behavior with the logit model (n = 467). Focusing on the first objective, the results of this study concluded that there is an impact on the farmers. The technology alone cannot improve animal health security in the short-term. In the second objective, the results concluded that, in the case of the PODD reporters, the decision of using monetary incentives to motivate most of the PODD reporters has a negative impact in the long-term. Losing reporter motivation and effort reflected to the low efficiency of the digital surveillance system of PODD and no impact on farmers. Concerning In the last objective, the results concluded that the optimistic bias of farmers has a very high impact on their decision making about reporting animal diseases on their farm. Just one infected farm in the case of dairy milk farmers can spread the foot-and-mouth disease to other farms. The new digital animal health surveillance system alone is not enough to reduce the impact of animal diseases of farmers. Suitable motivation for the reports and awareness of farmers optimistic bias in animal disease reporting cannot be neglected in digital animal disease surveillance system improvement. Overall, it can be concluded that the digital animal disease surveillance system is a powerful instrument for reducing the impact of animal diseases and increasing food safety and security. However, application of this advanced technology still needs time to demonstrate the impact and to be broadly adopted by users. In terms of motivation, the monetary incentive can increase the effort of report in the short run but it comes at a high cost and has a negative impact in the long-term. While the social incentive costs less and is more effective in the long-term. Where farmers animal disease reporting behavior is concerned, the optimistic bias is the highest influential factor on the farmers’ reporting decisions, in an inverse correlation.
Bildung und Forschung im Kontext der digitalen und ökologischen Transformation des Agrarbereichs im Banat und Baden-Württemberg - auf dem Weg zu Ressourceneffizienz und Resilienz
(2023) Weinmann, Markus; Landtag und Staatsministerium Baden-Württemberg , Universität für Lebenswissenschaften " König Michael I " in Timisoara; Raupp, Manfred G.; Ludewig, Uwe; Flad, Angelika
The Banat Green Deal project "GreenERDE" (Education and Research in the context of the digital and ecological transformation of agriculture in the Banat Region and Baden-Württemberg - towards resource efficiency and resilience) aimed to strengthen the the competitiveness of the agricultural sector in the Romanian Banat, Baden-Württemberg and neighboring regions with innovative technical and at the same time socio-cultural connect interesting content. The advanced training program “Farming in Responsibility for Our Common World” carried out as part of this project aims at the transfer of knowledge and experience among farmers and other interested persons. Current and future challenges, such as ecological conversion and the digital transformation of agricultural production, but also social, economic and cultural aspects were addressed. Innovative and relevant knowledge from practice, research or development projects throughout Europe and other continents is presented.
Bio-effectors for improved growth, nutrient acquisition and disease resistance of crops.- 2nd unrevised edition
(2019) Weinmann, Markus; Madora GmbH, Luckestr.1, D-79539 Lörrach; Raupp, Manfred G.
Recent scientific approaches to sustain agricultural production in face of a growing world food demand, limited natural resources, and ecological concerns have been focusing on biological processes to support soil fertility and healthy plant growth. In this context, the use of “bio-effectors”, comprising living (micro-) organisms and active natural compounds, has been receiving increasing attention. In contrast to conventional fertilizers and pesticides, the effectiveness of “bio-effectors” is essentially not based on the substantial direct input of mineral plant nutrients, neither in inorganic nor organic forms, nor of a-priori toxic compounds. Their direct or indirect effects on plant performance are rather based on the functional implementation or activation of biological mechanisms, in particular those interfering with soil-plant-microbe interactions. The general objective of the present research work was to improve the empirical and conceptual understanding concerning the utilization of bio-effectors in agricultural practice, following the principles of plant growth stimulation, bio-fertilization and bio-control. One main aspect of investigation was the application of bio-effectors to improve the efficiency of phosphorus (P) acquisition by the plant. Promising bio-preparations based on microbial inoculants (e.g. Bacillus, Pseudomonas, Trichoderma species) as well as natural compounds (e.g. algae extracts, humic acids) were tested in screening assays, greenhouse, and field experiments to characterize their potential effectiveness under varying environmental conditions. The most significant effects on plants appeared under severely low phosphate availability, but even under controlled conditions, bio-effectors required a narrow range of conductive environmental settings to reveal their potential effectiveness. Another focus of research was the application of bio-effectors to control soil borne pathogens, which typically appear in unsound crop rotations. Emphasis was set on take-all disease in wheat induced by the fungus Gaeumannomyces graminis. While the effectiveness of oat precrops to control take-all in subsequent wheat has been attributed to microbial changes and enhanced manganese (Mn) availability in soils, the take-all fungus is known to decrease the availability of Mn by oxidation. Against this background, the effectiveness of oat precrops and alternative crop management strategies to improve the Mn status and suppress the severity of take-all in wheat was investigated under controlled and field conditions. In conclusion, none of the tested supplemental treatments, such the application of microbial bio-effectors, stabilized ammonium or manganese fertilizers, could fully substitute for the multiple effectiveness of oat precrops, which was further confirmed by the results of a field experiment. Finally, some general conclusions and perspectives are summarized. Selected bio-effectors showed a strong capacity to improve the nutrient acquisition and healthy growth of crop plants under controlled conditions, but not in field experiments. However, even under controlled conditions the strongest effects occurred when plants were exposed to abiotic or biotic stresses, such as severely limited P availability or pathogen infestation of the soil substrate, still restricting plant growth to unproductive levels. Facing this situation, there is no perspective to improve the field efficiency of promising bio-effectors applications as a stand-alone approach. The only chance to develop viable alternatives to the conventional use of fertilizers or pesticides, for an ecological intensification of agriculture that maintains high yield levels, seems to be a reasonable integration of bio-effectors into the whole crop management of sound agricultural practice.
Biofector Herbarium Raupp
(2020) Hartman, Peter; Raupp, Manfred G.
Dynamisches Verhalten von Ackerschlepperreifen in Vertikal- und Längsrichtung auf fester Fahrbahn
(1997) Plesser, Joachim
Der Anteil von Transportfahrten von Ackerschleppern nimmt durch betriebsbedingte Veränderungen der landwirtschaftlichen Betriebe immer mehr zu. Zur schnellen Durchführung der Transporte stiegen deswegen die Höchstgeschwindigkeiten der Schlepper in den letzten Jahren immer mehr an. Die Fahrsicherheit und der Fahrkomfort der Ackerschlepper wird dabei insbesondere im oberen Geschwindigkeitsbereich maßgeblich vom Schwingungsverhalten der großvolumigen Niederdruckreifen bestimmt. Da der Standardschlepper in der Regel keine Aufbaufederung besitzt, sind es vor allem die Reifen, die die Fahreigenschaften beeinflussen. Um das Fahrverhalten verbessern zu können, sind zunächst die Federungs- und Dämpfungscharakteristiken für die vorliegenden Betriebsbedingungen zu ermitteln. An einem Bandlaufprüfstand werden an drei Versuchsreifen umfangreiche Reifenuntersuchungen bei Variation des Reifendrucks, der Radlast, der Reifentemperatur und der Fahrgeschwindigkeit durchgeführt. Das Fahrverhalten wird dabei durch ein von Langenbeck für die Vertikalrichtung vorgeschlagenes nicht-lineares Reifenmodell beschrieben. Dieses Modell wird weiterentwickelt und auf die Reifenlängsrichtung übertragen. Wesentliche Aussagen des Modells sind die nicht-lineare Federkennlinie und die degressiv abfallende Dämpfung bei zunehmender Geschwindigkeit. Das nicht-lineare Federverhalten sowie der degressive Abfall der Dämpfung läßt sich sowohl für die Vertikal- als auch für die Längsrichtung feststellen. Aus den Meßergebnissen werden die die Federungs- und Dämpfungseigenschaften beschreibenden Modellparameter ermittelt.
Einfluss der mechanischen und pneumatischen Anregung auf die Entmischung und Abscheidung in der Mähdrescherreinigungsanlage
(2021) Beckmann, Konstantin
Due to the legal limitation of the maximum machine width the throughput increase is realized by further developing of the process technology. This requires precise knowledge of the ongoing processes. The aim of this work is the metrological investigation of the combine cleaning system according to the white-box model by analyzing the process sequence of the sub-processes.This enhances process understanding and enables the validation and verification of DEM-CFDsimulations. The evaluation of the segregation and separation process is based on the movement behavior of grain and straw. For this purpose, 2D high-speed x-ray images, static 3D reconstructions and 2D high-speed camera images are analyzed. The segregation in the lower layers is limited by the compression of the material layer due to its own weight. Due to the higher porosity the segregation of the grain near the wall is slightly faster. Additional relative movements of the material based on the superimposed conveying process. The resulting voids are used for a faster segregation. The influence decreases with increasing mechanical and pneumatic excitation in vertical direction. The influencing factors on the movement behavior of the material in the cleaning system is investigated with a test-rig. In the unloaded state the airflow decreases along the sieve. Due to higher sieve loads the airflow is flatter. Therefore the maximum air speed under the lower sieve is shifted to larger sieve lengths. The front area of the upper sieve is less loaded. The air passes by these areas and causes an increase of the air speed. High air speeds in the winnowing steps result in a high grain separation. A high component of the air velocity in the conveying direction between the sieves causes a shift of the separation on the lower sieve to longer lengths. The air throughput must be within the limits between a sufficient material fluidisation and a low conveying process on the sieves. In addition to identifying development potential, the results are used to verify DEM-CFDsimulations. There are deviations of movement behavior between grain and straw. Nevertheless,the influencing factors can also be examined qualitatively on the basis of the simulations.
Einfluss dynamischer Radlastschwankungen und Schräglaufwinkeländerungen auf die horizontale Kraftübertragung von Ackerschlepperreifen
(2006) Schlotter, Volkmar
Given the large variation of application conditions of tractors and agricultural machinery, the force transmission between tyre and ground is of particular importance for the efficiency in agricultural use. For a proper assessment of the tyre the exact knowledge of the tyre force behaviour in vertical, longitudinal and lateral direction is required as well as their inter-dependences. Besides the steady-state behaviour the dynamic behaviour of the force transmis-sion is of high relevance. This thesis centres on the investigation of the lateral-force behaviour which is highly important for cornering, for driving on slopes, and also for vehicle roll. The steady-state and transient behaviour of the lateral force has been investigated using the Single Wheel Tester of Hohenheim University. Comparative tests for the longitudinal force transmission have been carried out. The focus was the assessment of dynamic behaviour under the influence of transient parameters particularly on rigid surfaces. The investigations for the steady-state lateral-force transmission show higher lateral forces for wider tyres especially in case of small slip angles. Tyre load has a strong influence on the cornering stiffness. A large increase in tyre load can lead to doubling the cornering stiffness. For small slip angles the lateral force tends to a maximum or even declines with increasing tyre load, so that for the same lateral force larger slip angles are required. The test results with non-steady-state slip angle excitation reveal a time delay in the lateral-force generation. This behaviour can be described by a time constant. An increase of the tyre inflation pressure from 0.5 bar to 1.6 bar leads to a decrease of the time constant by more than one third. A hyper-bolic decrease of the time constant with increasing driving speed confirms a stroke-dependency and leads in consequence to the introduction of a relaxation length. The relaxa-tion length derived from the measurements shows an increase with reduced tyre inflation pressure and rising tyre load. The values for the relaxation length are in a range of approx. 0.5 m to 1.6 m. A strong dependence on the respective method of measurement was found this means that measured values should always be reported in connection with the employed measurement method. With longitudinal force measurements the longitudinal stiffness, analogous to the cornering stiffness, was determined. For the longitudinal stiffness of the traction force values nearly twice as high are determined compared to the longitudinal stiffness of the braking force. For both parameters a nearly linear increase with the tyre load was found. The comparison of lug-excited and surface-excited tyre load fluctuations indicates a dominant influence of the lug excitation and the radial run-out of the wheel compared to stochastic excitations on road surfaces. For stochastic excitations in form of a bump the tyre load fluc-tuations are strengthened. A different behaviour of the lateral force with positive and negative gradient of the tyre load can be seen. Therefore the mean lateral forces are decreased for stochastic excitations. With low frequency excitations of the tyre load up to 2 Hz realised with the Single Wheel Tester the mean lateral force decreases by up to around 6%. The transient response of the lateral force has been determined using sinusoidal excitation of the tyre load. The relaxation length of 0.40 m to 0.75 m for tyre load excitation is lower than the relaxation length for slip angle excitation. Here as well a decrease with increasing tyre inflation pressure can be observed. Comparison with the results for the longitudinal force transmission under the influence of tyre load fluctuations shows that the time constant of the traction force amounts to only approx. one third of the time constant of the lateral force: the traction-force transmission reacts faster to tyre-load fluctuations than the lateral force transmission. Simulation of stationary lateral forces with various models shows good accordance with the measured results. For interdependent longitudinal and lateral forces the Slip-Drift-Model with appropriate adaptation of the input parameters shows good results. For modelling the non-steady-state lateral force transmission the Maxwell model was used. The spring and damping parameters have been determined with the results of measurements. An increase of the lateral tyre stiffness due to increasing tyre inflation pressure or reduced tyre load can be seen. The damping constant is strongly reduced with increasing driving speed, whereas the tyre load and the tyre inflation pressure have only a slight influence. The lateral damping constant is considerably higher than the vertical damping constant.
Entwicklung innovativer Pflanzenschutzprodukte und -verfahren als umweltfreundliche Alternativen zur Bekämpfung von Mehltaupilzen
Bericht im Rahmen des Forschungsprojektes: „Silizium als Aktivator bei Kulturpflanzen“
(2019) Raupp, Manfred G.; Weinmann, Markus; Arbeitsgemeinschaft industrieller Forschungsvereinigungen „Otto von Guericke“ e. V. (AiF) Projekt GmbH, Berlin; Madora GmbH, Lörrach; Römheld, Volker; Neumann, Günter; Blaich, Rolf; Merkt, Nikolaus
Powdery mildews are among the most important diseases in many crop plants. In all sectors of crop production (agriculture, viticulture, horticulture and orchards) powdery mildew fungi can cause severe damage under field as well as greenhouse conditions. Although organic synthetic fungicides have been used to combat powdery mildews in conventional and integrated agriculture for decades, organic farming lacks effective alternatives to the ecologically questionable sulfur fungicides. Yet, also for integrated or conventional crop production, alternatives or supplements for a reduction and more effective use of synthetic fungicides would be desirable to optimize the production of high quality food with the help of environmentally friendly means. Objective of the present work was the development of innovative crop protection products and application strategies to combat powdery mildew fungi with respect to the knowledge on resistance-enhancing effects of an improved silicon (Si), manganese (Mn) and zinc (Zn) supply to the plants. Furthermore, various plant extracts have recently received renewed attention. Among other active natural agents, garlic (Allium sativum L.) is known for its fungitoxic effect and at the same time high Mn and Zn contents. With the present work, an overview of possible approaches to control powdery mildew in grapevine by use of Si, Mn, Zn and plant extracts from garlic has been elaborated in greenhouse experiments. In this regard, the physiological significance of Si, Mn and Zn for the expression and strengthening of plant own resistance mechanisms was distinguished from the effectiveness of spray applications for forming passive silicate crusts as mechanical infection barriers. The physiological Si status of the plants could be clearly improved only by soil rather than foliar application of silicates. Regarding the soil application of silicates, however, no practical applications are known, how silicon fertilizers can be distributed under field conditions in the soil and brought into the rhizosphere to continuously ensure high rates of Si uptake. There is also still considerable uncertainty whether the soil application of silicates in non-Si accumulators, such as grapevines, can result in sufficient Si uptake for an effective expression of resistance mechanisms. The most impressive effects in the control of powdery mildew were achieved with the spray application of potassium silicate in combination with wetting agents to form silicate crusts on the leaf surface. The positive influence of Mn and Zn on the effectiveness of spray applications of potassium silicate and the adequate compatibility of Mn and Zn chelates with potassium silicate suggest that the interactions between Si, Mn and Zn should be considered for further product development. The application of garlic extract did not result in sufficient efficiency, although protective and curative properties could be observed. Allicin, supposed to be the active ingredient of garlic extract, has a broad spectrum of antimicrobial activity and is one of the few agents for which no development of resistance has been found in microorganisms so far. Therefore, the interest in this agent for the development of biological plant protection products is expected to increase.
Entwicklung und Applikation eines instationären Reifenmodells zur Fahrdynamiksimulation von Ackerschleppern
(2009) Ferhadbegovic, Bojan
The driving speed of modern agricultural tractors increased continuously during the last years. Nowadays, a maximum driving speed of 50 km/h is standard for agricultural tractors in Germany. To be able to drive safely at such high speeds, the agricultural tractors are equipped with a suspended front axle. However, a rear axle suspension for standard tractors is still too expensive and has thus not prevailed yet. The increasing percentage of transportation duties and the efforts to increase the productivity generate a high demand for even faster agricultural tractors. Therefore, the first standard tractor with a maximum driving speed of 60 km/h was presented in 2005. This speed was achievable without a major change of the vehicle?s basic design. However, even higher driving speeds will require substantial modifications of the vehicle?s concept and are thus not expected very soon. Since the agricultural tractors are designed mainly for the field work, their driving dynamics characteristics on the road are not always perfect. The high vehicle masses, possible insufficiencies in the construction and interaction of various vehicle components together with the missing rear axle suspension can lead to critical behaviour of the vehicle, especially during high speed cornering. The entire suspension on the rear axle is accomplished by the tyres. Since the agricultural tyres are mainly designed for carrying high loads and generating high draft forces on soft soil, their driving dynamics properties on the road are rather insufficient. They usually have a radial run-out with an amplitude of 1-2 mm. Due to the rather low damping of the agricultural tyres, this rather small run-out can cause vibrations with a quite high amplitude, especially if the excitation is close to the eigenfrequency of the vehicle. Furthermore, the tyre inflation pressure varies between 0.8 and 2.0 bar - which is a relatively large span - making the vehicle setup more difficult. To analyse the driving dynamics of agricultural tractors and to identify possible problems and insufficiencies at an early stage of development simulation models are used. A very important part of a vehicle model is the tyre model. Being the link between the vehicle and the ground, the tyre has a high influence on the vehicle behaviour. It is therefore essential to use an accurate tyre model. Most of the commercially available tyre models today are optimized for passenger car tyres and are thus of limited use for soft and large agricultural tyres. In this doctoral thesis at the University of Hohenheim a dynamic model for agricultural tyres on rigid surfaces was developed ? the Hohenheim Tyre Model. It is a hybrid model since it needs physical parameters like spring and damper coefficients as well as empirically obtained data for the tyre-ground-characteristics. The Hohenheim Tyre Model uses the wheel speeds and the speed of the tyre tread to calculate the deflection velocity and the deflection of the tyre and subsequently uses both values as inputs for spring-damper-elements. The force calculated in these so-called Voigt-Kelvin-Elements is finally used to determine the slip and the slip angle of the wheel. The tyre model was created in MATLAB/Simulink and can be coupled to any multi-body-software. The model allows to calculate the transient tyre behaviour in three dimensions with a low computational effort, which makes it adequate for driving dynamics simulation. It takes the nonlinearities of the tyre into account and calculates the forces for pure longitudinal or lateral slip as well as for combined slip conditions.
Experimental investigations on tractor tire vibration properties
(2017) Brinkmann, Christian
Vehicle vibrations have raised articulate awareness in agricultural industry during the last years. Especially, the legal basis with the EU directive 2002/44/EC and its implementation into national law with the corresponding ordinance have sensitized the manufacturers concerning the vibration behaviour of their vehicles accompanied with an increasing demand for ride comfort by the customers. Furthermore, vehicle components’ stress due to vibration and shock is also significantly dependent on the tire’s vibration characteristics. Only an optimized design and combination of the vehicle components can reduce vibrations and improve ride comfort and endurance strength. In this thesis mechanical vibrations in the ride comfort frequency range between 10 Hz and 80 Hz are regarded. For the investigations a new mechanical shaker device has been developed and single frequency force excitations in the mentioned frequency range can be applied to a rolling tire. From excitation and response of the system it is possible to identify the vibration modes of the rolling tire. The shaker is designed to be applied both to a flat-belt test stand and a research tractor. Additionally, uniformity and cleat tests have been conducted with the research tractor in order to compare shaker, tire and impact excitations.
Experimenteller Beitrag zum Schräglauf- und Lenkmomentverhalten rollender Reifen landwirtschaftlicher Fahrzeuge auf starrer und nachgiebiger Fahrbahn
(1991) Heine, Adolf
Beim Einsatz landwirtschaftlicher Fahrzeuge können zwei Fahrzustände mit schrägrollenden Reifen unterschieden werden. Die Spurhaltung beim Fahren am Hang oder beim Pflügen erfolgt durch konstant (stationär) schräglaufende Reifen, wohingegen Lenkvorgänge zur Änderung der Fahrtrichtung als instationäre Fahrzustände anzusehen sind, weil sich der Reifenschräglauf hierbei ständig ändert. Um das instationäre Schräglaufverhalten der Reifen landwirtschaftlicher Fahrzeuge auf starren und nachgiebigen Fahrbahnen untersuchen zu können, wurde als Versuchseinrichtung ein Einachsanhänger mit stufenlos gegeneinander einlenkbaren Versuchsreifen und einer Fünf-Komponenten-Kraft- und Momentmessnabe entwickelt.
Exportstrategien und deren Anforderungen an Management und Organisation
(2019) Raupp, Manfred G.
Gerbers biographisches Lexikon der Agrarwissenschaften
Persönlichkeiten aus Land- und Forstwirtschaft, Gartenbau und Veterinärmedizin ; Festausgabe zum 90. Geburtstag von Th. Gerber
(2021) Boettcher, Hartmut; Raupp, Manfred G.; Gerber, Theophil
Grundlagenuntersuchungen am Mähdrescher-Vorbereitungsboden mit pneumatischer Unterstützung
(2017) Schwarz, Michael
Nowadays the cleaning unit in combines is often the power limiting assembly unit. There are no additional accelerating fields acting to segregate and separate grain besides gravitational acceleration. A strengthened pre separation of the material mixture acting in front of the winnowing step in the combine can increase the power of the cleaning unit without additional accelerating fields. A pneumatically supported separation process at the preparation floor is a promising measure. The target is to generate a fluidized bed. Conveying and segregation at the preparation floor are modeled following different approaches. The analytical description of the conveying at the pneumatically supported preparation floor by means of extended point mass approaches in conjunction with a stochastic description of the segregation is suitable for conventional modeling approaches for complex process engineering processes to a limited extent. For the experimental evaluation of the conveying and segregation a test rig with an additional fan at the preparation floor is developed. The test rig allows the determination of grain losses, cleanliness, return and separation characteristic in the cleaning unit. As typically handled in combines the feeding of the material is handled via the preparation floor and return pan. In order to be able to assign the grain losses to the point of delivery, the grains transported on the return pan are coloured. To evaluate the segregation at the preparation floor, the average height of the grain above the preparation floor is to be determined. This determination is done by means of a high-speed camera recording with subsequent particle tracking. The investigations at the preparation floor without pneumatically support show that the segregation at the preparation floor is restricted at high throughputs. Furthermore, it demonstrates that upon increasing throughput the proportion of the grains in the share of grain losses from the return pan increases disproportionally higher than the total grain losses. The design notes derived therefrom include the adaptation of the preparation floor length as well as the optimization of the return pan’s connectivity to the cleaning unit. By means of a pneumatic support arranged in the last third of the preparation floor, a fluidized bed is generated in the investigation, which increases the work efficiency of the cleaning unit by approximately 10%.
Hohenheimer Lexikon der Agrarbiografien
„Persönlichkeiten aus Land- und Forstwirtschaft, Gartenbau und Veterinärmedizin“
(2025) Boettcher, Hartmut; Raupp, Manfred G.

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