A tractor ( plural tractors, from the Latin trahere “ to pull” or “to drag”), also tractor , field tractor or even just tractor , is a tractor that is used in agriculture to pull and drive agricultural machines . Since tractors are used on unpaved and arable land, they are designed for high off-road mobility and robustness. Modern tractors therefore often have all-wheel drive .
Outside of agriculture, tractors are used in forestry, municipal operations, horticulture, emergency services (fire brigade, Thw), airports and construction (road construction, earthmoving, horticulture and landscaping). In northern and central Germany tractors are also referred to by the term tractor , which is derived from the Low German word trecken ("to pull"). In southern Germany, the terms bulldog or tractor are sometimes used as a synonym for tractor . In Austria and Germany, the official traffic law name for a tractor is a tractor .
Soon after the invention of the steam engine towards the end of the 18th century, attempts were made to replace the previously predominant pull of agricultural implements with draft animals by the new power engine . From the 1870s onwards, the use of self-propelled locomobiles , i.e. steam tractors , for the direct pulling of agricultural equipment became increasingly widespread. Due to the high weight of a traction engine compared to the drive power, these were only suitable on particularly stable soils such as those of the American prairie , but not on the more deep and less stable arable soils of Europe. This was remedied by an invention by the Englishman Heathcote, by means of which agricultural implements were pulled over the field by means of a rope pull from locomotives standing on the edge of the field, the so-called plow locomotives . Well-known manufacturers of steam tractors were, for example, Marshall, Mc Laren , Fowler or Burell in Great Britain and Wolf , Kemna or Lanz in Germany.
With the increasing spread of the internal combustion engine from around the turn of the 19th to the 20th century, tractors were also equipped with them. However, they did not differ significantly from the steam tractors in terms of construction, appearance and dimensions ( power to weight ratio around 100–120 kg / hp) and could therefore only be used under similar conditions. In 1892, the German-born American John Froehlich invented a tractor with an internal combustion engine. Typical examples of this tractor development are the Marshall Colonial Tractor from Marshall & Co , Gainsborough, United Kingdom, or the Rumely Oil Pull from Advance-Rumely , La Porte, Indiana, USA.
A development leap away from the heavy and capital-intensive steam tractors was first made by Ford Fordson in the USA with the Model F with four-cylinder gasoline engine presented in 1917 , in which the frameless block design, which is still widespread in tractor construction, was used for the first time. The approximately 20 hp Fordson with its low power-to-weight ratio of 62 kg / hp (dead weight: 1230 kg) also allowed use on soils with little load-bearing capacity; In addition, efficient mass production enabled a very low price of US $ 750 (1917) for the first time. The Fordson brought about a surge in motorization, especially in agriculture in the USA and on the British Isles, so that by 1920 around 100,000 Fordson were already in use.
A comparable development in the mechanization of agriculture did not start in Germany until the mid-1920s, especially with the start of production in 1921 of the first Lanz tractor model, the Lanz Bulldog HL12 with a robust and inexpensive hot - head motor , which, as a multi-fuel motor , made only low demands on the fuel and also with the considerably cheaper crude oil could be operated in Germany. These very well-known and widespread " Bulldog" tractors with glow head engines were manufactured and further developed even after the Second World War and served as a model for many replicas around the world. Today Lanz Bulldogs achieve fan prices and can be found at every meeting of historic tractors. In various parts of Germany, the name Bulldog became a colloquial synonym for the term tractor. The Lanz plant in Mannheim was taken over by John Deere in 1956 and is now the largest tractor factory in Europe .
From the beginning of the 1930s onwards in Europe, largely with the success of the Deutz tractors of the MTH model series (from 1924), as well as FM 315 (from 1933) and FM 414 " Bauernschlepper" (from 1936), the diesel engine was also increasingly used as a drive source while gasoline engines were also widely used in America for a long time . Until the 1960s, tractors had rather low engine outputs, but high torques and heavily reduced transmissions . Modern tractors often have more than 100 kW of power and some types can reach speeds of up to 80 km / h .
The inventions of the rear three-point suspension with hydraulics ( three-point hydraulics ) by Harry Ferguson and the power take-off shaft , which became generally accepted from around 1960, were also pioneering in tractor development . Thus, the agricultural tractor became a very versatile implement carrier .
Constructive features and development directions
Almost all tractor manufacturers around the world use paintwork in their brand-specific colors . In contrast to this, tractors for use in municipal services, such as road maintenance services, are usually delivered ex works in a typical shade of orange.
Cabin equipment and controls
- Modern tractors are often steered with (electro) hydraulic support (steering assistance) from the mechanical transmission components or else fully hydraulically . With the latter steering systems, the steering forces are at least partially transmitted hydraulically via pipes or hoses. Fully hydraulic steering allows the use of automatic steering systems, which are controlled by electronic sensors and steer the tractor along a guideline (tramline, row of plants, etc.) over the field without the driver's intervention.
- The cabin doors are usually frameless and attached to the B-pillar (the second counting from the front) that open towards the front. The Schlüter company used sliding doors.
- Air conditioning systems are standard equipment in the current, larger models. They enable the driver to work in a dust-free, noise and vibration insulated cab.
- The most common tractor accidents are caused by tipping over. In Austria, vehicles have therefore had to be equipped with a roll bar since 1960, and in Germany since the early 1970s . In the course of this, roll-over-proof cabins were increasingly being built.
- The driver's seats are sprung as standard, with simple, mostly smaller models up to 70 HP, mechanically, as well as an air spring and damper. Relatively new are air suspensions, which actively counteract vibrations and thereby greatly reduce the load on the driver's intervertebral discs in the field.
- As standard, the brake system is designed so that only the wheels on one side of the tractor can be braked in order to support the steering at low driving speeds to achieve small turning circles (steering brake). For this purpose, there is usually a two-part brake pedal that can usually be mechanically coupled for braking on both sides, for example for road travel. Exceptions to this are, for example, the steering brakes on some Kramer tractors, which are activated via the steering wheel when the steering is turned, or the ABS braking system from the manufacturer Case-New Holland, in which the brake pedals are electronically coupled depending on the speed.
- The wide range of setting options for the motor-gearbox coupling, the lighting and the extensive hydraulic settings mean that monitors for setting instead of rotary knobs prevail in the cab.
- As a rule, tractors have a hand throttle with which a certain engine speed can be set without having to constantly use the pedal. The hand throttle is required, among other things, for PTO work with the tractor at a standstill, for example to operate pumps.
- Hop cabins are available especially for hop growing , which are trapezoidally narrower at the top so that they can drive through the crops without damage. In addition, low cabins are available so that low buildings can also be entered.
- The front window can optionally be opened so that in winter there is a clear view of the stables in spite of the fogging window. The rear window can be opened as standard.
- If the tractor is equipped with a reversing device, the tractor seat together with the operating and control elements can be rotated 180 degrees against the normal direction of travel for longer operation of the tractor. The advantage of the reversing device is that you have a clear view of the rear linkage and the attachment mounted on the rear. The tractor rear axle is also usually more resilient than the front axle. Heavy attachments which are to be operated in front of the tractor wheels and which exceed the permissible values for front axle load or front hydraulic lifting force can nevertheless be operated in push travel. With reverse drive systems, beet harvesters, forage harvesters, mowers and forest machines are used, among other things.
Transmission, axles and power take-offs
As a rule, tractor transmissions have more gear steps than are common in cars or trucks. The extremes on the market range from eight forward and four reverse gears to 72 forward and reverse gears. For operation, there are usually several shift levers with, in some cases, additional electric switches to select the gears that can be shifted under load ( powershift transmission ). For some years now, hydro-mechanical transmissions have also been available that allow infinitely variable tractor speeds of around 20 meters per hour to 60 km / h, regardless of the engine speed and without interrupting the power flow.
When using tractors, the following speed ranges are often required:
- 20 to 300 meters per hour in use with road construction cutters or with special crops (e.g. vegetable or strawberry cultivation)
- 3 to 10 km / h for typical agricultural work such as tillage, feeding, fertilizing and plant protection applications
- 11 to 20 km / h for light tillage, mowing
- > 20 km / h for transport
A tight gear ratio is also beneficial for transport work, since the ratio of power and total weight of the train is often lower in tractors than in trucks.
The following devices can significantly improve the pulling or work performance of a tractor:
- Continuously variable transmissions allow a complex combination of engine and transmission control, so that the engine can be operated predominantly at optimum consumption or performance.
- In view of the increasing top speeds (up to 80 km / h with the JCB Fastrac) and the low damping of the large-volume tractor tires, the majority of modern tractors are equipped with front axle suspension , usually via a hydraulic or pneumatic system. Tractors with suspension on all axles (for example JCB Fastrac) are so far not very widespread, although they bring advantages in terms of driving comfort, driving safety and soil protection.
- Differential locks are installed as standard so that if the wheels on one axle have different levels ofgrip,the wheel with the lowergripdoes not have increased slip or even spin, while the other wheel is decelerated to a standstill on the more grippy ground due to the action of the unlocked differential. Differential locks are also available on tractors in different designs: partly automatic locking differential , partly manually activated by a switch or pedal. The differential locks also differ in terms of their locking effect. In some cases, they rigidly connect both wheels on an axle so that there is a complete locking effect. Other designs allow a certain speed difference between the wheels.
- Ground PTO shafts are a special type of PTO shaft . They can be used to drive the axles of special trailers in order to improve the traction of the train on difficult terrain. For example, the tractive power of small tractors of the post-war period could be better used with single-axle manure spreaders. The speed of the ground speed PTO depends on the selected gear and the engine speed and is switched via the drive clutch.
- Modern tractors are usually equipped with switchable all-wheel drive . Purely rear-wheel drive machines have become the exception. The all-wheel drive has widespread what is known as lead: the front wheels reach an approximately two percent higher speed than the rear wheels and thus prevent tension in the transmission when cornering. The inevitable slip can be tolerated as long as there is no road travel or work at speeds above 15 km / h.
- Ballast weights are added to improve the interlocking of tires and soil, or to compensate for unequal loads from front loaders or heavy rear implements. A typical mounting location is a bracket on the front of the tractor, but there are also weights with three-point attachment for attachment by the front or rear linkage, as well as wheel weights for screwing into the wheels. Furthermore, the tires can be (partially) filled with a mixture of water and antifreeze for further stress. The Eurotracs from Schlüter had a hydraulically displaceable weight arranged above the front axle.
Laws and requirements
Agricultural tractors usually do not need a tachograph that records the driving and rest times as in trucks . Tachographs were under discussion for transports for commercially operated biogas plants . However, with the engine output, some of which is similar to that of a truck, the dimensions and total train weights of 40 tonnes, the need for a tachograph remains under discussion.
- Practically all common basic types have been or are being installed as tractor engines, from single-cylinder to V8, V12 or 8-cylinder in- line engines (some Schlütertypes). Standard today, however, are vertical diesel in-line engines with 3, 4 or 6 cylinders, which can be set to different outputs via the factors of displacement , charge air cooling , exhaust gas turbocharger or adjustable injection pumps.
- Up to now, motor elements and their direct add-on parts such as compressed air supply systems have been driven as required. Developers have presented the first solutions in which radiator blades, compressed air procurement or hydraulic pumps only consume engine power when required thanks to electric drives ( e.g. John Deere E-Premium).
- Alternative drive systems such as hydrogen drive or biogas drive will be ready for series production in a few years. In contrast to cars or trucks, there is no need to pay attention to the remaining payload or the required installation space, since both can easily be expanded with tractors. The only construction hurdle compared to cars and trucks are the massive vibrations during off-road operations.
- Diesel- electric drives for tractors were also planned. In particular, the Eltrac based on a New Holland of the M series should be mentioned here. So far, none of the alternative drive forms have made a market breakthrough.
Wheels and tires, caterpillar drives
Most tractors have four wheels, with the front wheels generally having a smaller diameter than the rear wheels. This characteristic difference in size is due, on the one hand, to a smaller turning circle due to the larger steering angle possible with smaller front wheels and a better view of any front-end implements. On the other hand, the rear wheels, which are not steered in the standard design, have a larger diameter, since larger wheels can generate a higher tractive effort due to their lower rolling resistance, especially on yielding arable soils, and exert less pressure on the ground due to the larger contact area. The design with four wheels and smaller front wheels is the most widespread and is therefore called the standard design, but there are also tractors with only two wheels ( single-axle tractors ), three wheels (for example from Horsch machines or the three-wheel tractors from the no longer existing manufacturer Ritscher), four wheels of the same size (for example MB-Trac or articulated tractors such as Kirowez K-700 ), six wheels ( Fendt Trisix, Rasant Weinberg-Trac) or even eight wheels ( Deutz-Fahr Agro XXL 8).
The tires of the tractors usually have a coarse tread pattern in order to ensure the highest possible traction through good interlocking with the arable soil. For tractors primarily used on grassland , tires with lower and smaller studs are used to protect the sward.
- Terrar tires are balloon-like, particularly wide, low-pressure tires which, due to their larger contact area, distribute the vehicle weight better and thus reduce soil compaction caused by driving on.
- For maintenance work (for example to control weeds ) while the crop plants are growing, narrower, so-called maintenance tires can be used. These are only 9 to 14 inches wide. The care tires have the advantage that either the tractor track remains between the plants that are at the usual distance or only a few plants are damaged by being driven down. On the other hand, due to the small contact area, the disadvantage is the higher ground pressure , which can lead to greater soil compaction , especially when it is wet . With regard to the increasing working widths of fertilizer spreaders and field sprayers, maintenance tires have lost their importance, since with larger working widths of these implements it can be more profitable in terms of yield, for the normal wide tires of the tractor when sowing or planting the crop, a smaller number of wider ones To leave tramlines unordered. In addition, the labor-intensive and dangerous changing of the tractor wheels, which are up to two meters high, is no longer necessary.
- There are also twin or even triple tires for working on poorly stable ground. For this purpose, an additional wheel (two with triple tires) is mounted on the actual wheel of the tractor. The vehicle width is then often no longer in the roadworthy range.
- With the tire pressure control systems available as special equipment, the tire pressure can be reduced to 0.7 bar, for example, or too fast transport trips to increase the contact area ( walking effect ) and thus reduce the ground pressure, e.g. when working in the field, without the driver getting off increase the road in the interest of higher load capacity and lower wear due to less flexing work to up to 2 bar.
- Crawler drives (cf. tracked vehicles ) are used in special cases or in large-scale agriculture because of their lower contact surface pressure (ground pressure). For some years now, treadmills made of reinforced rubber have been preferred to steel chains despite their lower tensile force, since they can be used on roads. Track drives are currently mainly used in large tractors with an output of 221 kW (300 hp) or more. In the Soviet Union , tractors with caterpillars were manufactured in large series for agricultural use for many decades. Examples are the SChTS-NATI , DT-54 , the T-74 or the DT-75 .
- Steel grab wheels have also lost their importance. They are only still used in rice cultivation or in single-axle tractors.
Liaison points to agricultural machinery and trailers
Connection of tractor and device
- Trailer coupling (front and rear via 40 mm bolts)
- Piton fix
- Ball head coupling K 80 backlash-free coupling ball similar to the car attachment in a reinforced version
- Three-point hydraulics at the rear (rear linkage ) and at the front (optional front linkage ), with self-locking quick-release couplings, also known as catch hooks (optional)
- Quick coupling triangle (Weiste triangle)
- Front loader (optional)
- Municipal mounting plate
- Fifth wheel coupling on large tractors
- Between- axle attachment, historical significance for mower attachments
Energy transfer process
- PTO at the rear (optional at the front): The kinetic energy (rotation) generated by the engine is transferred to the attached implements via the crankshaft and PTO gearbox. With the standard (motor) PTO shaft, a speed of 540 or 1000 revolutions per minute is switched via an intermediate gear if required. As a rule, this is the maximum power of the engine at around 2000 engine revolutions. So-called economy or ECO PTO speeds are also available. They reach the 540 or 1000 standard speed with a fuel-saving 1600 engine revolutions and are suitable for lighter work such as for hay tedders . A special case is the 430 standard speed, which is reached at 2000 engine revolutions. This speed, which is mainly offered in mountainous regions, allows a loader wagon to be driven slowly at the rear with a simultaneous 1000 rpm for the front PTO. There, a front mower gets its full speed, while the loading wagon in the rear with its conveyor unit (called a pick-up ) works slowly, protecting the turf.
- Power connection with 12 volts for low-consumption motors and actuators as well as for driving lights of the field devices and trailers
- Power connection with 400-volt plug for driving low-consumption devices such as fertilizer spreaders. So far, this project by the manufacturer John Deere is not yet ready for series production and has not been approved for widespread use by professional associations.
- Hydraulic connections at the rear (optionally at the front or on the ascent) for driving and controlling motors and valves on field devices, front loaders and trailers: The tractor's hydraulic pump generates an oil flow that transfers the kinetic energy generated by the tractor engine via lines to the vehicle's own force converters or to the field devices ( single and double-acting lifting cylinders or hydraulic motors). In addition to conventional gear pumps, there is an increasing number of axial piston pumps that only require greater drive forces from the motor when they are controlled.
- Rear hydraulic connection for controlling the trailer brakes. This method is common in EU countries other than Germany and is permitted for trailers with a gross vehicle weight of up to 8 tons. In certain countries there is no weight limit for hydraulically braked trailers.
- Compressed air connection for brakes on trailers (optional): Today this connection consists of a yellow brake line and a red supply line and is therefore compatible with truck trailers. Until the 1980s, a single-line brake system was common, in which a black brake hose with a larger cross-section had to take over all functions. In the meantime, this single-line brake system only has protection as it is in agriculture, but for safety reasons it can no longer be installed on new trailers.
- Belt pulley for driving threshing machines with transmission belts , for example , as well as a variety of other accessories, such as large grinder , threshing machine , wind sweeper , baler , hay and crop conveyor, forage harvester (crop chopper ), stone breaker , (firewood) circular saw , cone splitter , water pump, workshop machinery and others Machines by flat belt . This energy transfer was mainly found in tractors built around 1955.
Use and special designs
There are now tractors of all shapes and sizes for many purposes:
- Slope equipment carriers, which can be used primarily in the mountains in forestry or alpine farming , with a wide track and a particularly low center of gravity for high tipping safety on slopes,
- narrow tractors for the wine or hops ( vineyard tractors ),
- Tractors with inter- axle mounting space, very strong steering lock and many control units,
- Portal tractors with extremely high ground clearance for special crops such as tree nurseries,
- Large tractor for arable farming in the lowlands on large fields .
Special forms are the Unimog , the Claas "piggyback" the equipment rack and the so-called mules , which are designed mostly with a slightly longer wheelbase than other tractors. The implement carrier has an additional mounting space in front of or above the underfloor engine for additional machinery (alternatively a loading platform), while the Unimog and Muli are provided with a transport area behind the driver's cab and are very off-road. The Muli is mainly used in western Austria, Switzerland and South Tyrol .
The so-called Trac tractors ( MB-Trac , Deutz INTRAC , JCB Fastrac , Claas Xerion (this one with a hydraulic swiveling and sliding cab)), in which the driver's workplace is positioned further forward or in the middle between the axles, deviate from the conventional standard design from. In addition, there are articulated tractors , which are mainly used in forestry.
Deutz-Fahr Agro XXL with 4 axles and bogie axle suspension
With regard to the attachment to the tractor, a distinction is made between:
- Attachments that are (flexibly) hooked into the three-point hydraulic system and
- Construction devices that are (very resilient) firmly connected to the frame.
Attachment devices can be found, for example, on tractors with forest-specific or communal equipment (e.g. cable winches , pile shields, attachment cranes or excavators, boom mowing equipment). Such tractors form the transition to special machines ( e.g. special forest machines with articulated steering ).
Many devices that used to be powered by a tractor are now so large and special themselves that they have established themselves as independent, self-propelled machines, such as combine harvesters , forage harvesters , harvesters or special forest machines.
A new development is that attachments are connected to the tractor via the ISOBUS bus system . They are then uniformly controlled via a bus terminal integrated in the tractor, without a separate control unit having to be installed in the tractor for each device. Retrofitting of older tractor models with bus terminals is also possible.
Tractors on public roads
Driving license law
The driving license classes for operating agricultural equipment are nationally regulated in Europe. They do not apply internationally.
In Germany, driving a tractor for agricultural and forestry purposes requires a national class L driving license (up to 40 km / h maximum speed determined by the type of construction, with a trailer with appropriate identification by a speed sign prescribed in accordance with Section 58 of the StVZO up to 25 km / h ) or class T (up to 60 km / h, also with a trailer) required. It should be noted that the above-mentioned driving license classes only apply to driving corresponding vehicles if the journey is carried out for agricultural or forestry purposes. This applies to driving licenses issued since January 1, 1999. If a driver's license issued before this date has been rewritten, the earmarking of class L is usually canceled by entering the code number 174. For use for agricultural or forestry purposes, classes B (E), C1 (E) and C (E) are also sufficient, but the respective restrictions regarding the permissible total weight and the number / weight of trailers must be observed.
If tractors are also to be used for journeys that are not used for agricultural or forestry purposes (e.g. to exhibitions), then the driving license class B (up to 3.5 t), C1 (up to 7.5 t) corresponding to the gross vehicle weight of the tractor is required t) or C (over 7.5 t) required. When towing a trailer, the corresponding trailer driving license class BE, C1E or CE may be required.
If the tractor has a design speed of no more than 10 km / h (and therefore no license plate), the tractor is considered a wagon and no driving license is required. For faster tractors whose design speed does not exceed 50 km / h, a driving license or a class F driving license is required. In addition, trailers with a total weight of over 750 kg can be towed without the need for an additional driving license.
For tractors with a design speed higher than 50 km / h, either a class B driving license is required (for tractors up to 3500 kg maximum permissible total mass) or class C.
The class F driving license is only valid in Germany.
In Switzerland it is possible to obtain a category G driver's license from the age of 14. This allows agricultural motor vehicles to be driven up to a speed of 30 km / h. After participating in the special course G40, from the age of 14 it is allowed to drive 40 km / h with the towing vehicle and trailer. This course lasts two days and includes theory and practice. An F driving license can be obtained from the age of 16, which also allows a maximum speed of 40 km / h. Agricultural vehicles are not allowed to drive faster in Switzerland.
There are no restrictions on the weight of the vehicles or trailers. The three categories G, G40 and F are 'free' when purchasing category B.
Accidents involving tractors on public roads
Agricultural tractors (tractors) are comparatively rare on Germany's roads. Therefore, their involvement in accidents is also relatively low. In accidents involving tractors, however, an above-average number of people are seriously injured or killed. For this reason, the Accident Research of the Insurers (UDV) has investigated where such accidents occur under which circumstances with the involvement of tugs. For this purpose, an accident database with 1010 accidents from 2006 to 2008 from all over Germany was set up and analyzed. It was shown that serious accidents with tractors mainly occur outside of town and that, in relation to the general population, an above-average number of young drivers are involved in them. The main areas of accidents are intersections, junctions (for example on dirt roads), curves and property entrances and exits. Accidents with motorcycles, in particular, often end very badly.
The UDV recommends better training of young tractor drivers in order to mitigate or completely avoid accidents with agricultural tractors. Furthermore, all road users should be better informed about the particular risk of accidents with tugs. The signal image of tractors with and without trailers must be improved, for example through the approval of all-round lights, reflective foils, marker lights and contour markings. Tail lights and turn signals should be both larger and more stable.
Tractors as a hobby
Classic car friends
Since around the 1970s there has been an increasing number of tractor enthusiasts in Germany and Austria who restore old tractors and the associated attachments and make them drivable again. The tractor lovers often come together in interest groups or registered associations that organize tractor meetings with various demonstrations and trips in the respective regions. The clubs are mostly called tractor friends, bulldog friends, friends of old agricultural machinery, etc. and are partly brand-related ( Lanz , Eicher , Hanomag , Belarus , progress , Deutz , Fahr , Fendt , Güldner , Porsche , McCormick , Unimog , Schlüter , etc.) in Austria There are traditional clubs that collect and maintain one of the first Steyr models, the so-called 15-series , which was first built from the late 1940s to the 1960s .
Tractor pulling / tractor haul
So-called sports tractors, which are used for tractor pulling , a motor sport that emerged in the USA in the 20th century and spread across Europe in the early 1980s, have particularly high outputs . Tractor pulling is about pulling a brake truck, which increases its pulling resistance depending on the route, as far as possible on a 100 m runway. In the free class , the tractors have up to 7400 kW (10,000 hp ).
The population's increasing passion for collecting historic agricultural machinery also led to the issuance of various specialist magazines , which, after the long dominance of classic club news, enriched the market with professional journalistic products. These publications are mostly available from station bookshops. They provide information in magazine format and in color about restoration projects, club activities, tractor meetings and much more.
- Tug mail (Verlag Klaus Rabe)
- Oldtimer tractor (VF Verlagsgesellschaft mbH) - combined with "AgroClassic"
- Tractor Classic (Geramond)
However, these magazines rarely make their content available on the Internet. Independent journalists jump into this breach (especially in English-speaking countries) who make their reports accessible, for example in the form of blogs.
The leading magazines for current agricultural technology are:
- profi (Landwirtschaftverlags Münster)
- top agrar (Landwirtschaftsverlag Münster)
- as well as the agricultural weekly papers such as the LZ Rheinland
- farmers weekly
- Agricultural tires
- Rail tractor
- Road-rail vehicle
- List of agricultural implements and machines
- Agricultural mechanization
- Nick Baldwin: Classic tractors from around the world. The image lexicon of brands and models from all over the world . Motorbuch-Verlag, Stuttgart 2005, ISBN 3-613-02572-8 .
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- Klaus Krombholz, Hasso Bertram and Hermann Wandel: 100 years of agricultural engineering - from handcraft to high-tech in Germany . DLG-Verlag, 2009, 320 pages; ISBN 978-3-7690-0737-4 .
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- Search for tractor in the German Digital Library
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- Photo of a tractor with iron wheels for use in rice fields
- Armin Bauer: Schlepper: The history of the development of a commercial vehicle . FranckKosmos, Stuttgart 2004, ISBN 3-440-09664-5 , p. 6 f.
- Harold P. Manly: The Ford Motor Car and Truck; Fordson Tractor: Their Construction, Care and Operation. Frederick J. Drake & Co. 1919, Chicago, IL, USA.
- Fordson Model F. Ford Oldtimer und Motorsport Club Cologne eV in ADAC (fomcc.de), accessed on April 7, 2019.
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- Robert N. Pripps, Andrew Morland: Farmall Tractors: History of International McCormick-Deering Farmall Tractors. Farm Tractor Color History Series, MBI, 1993, Osceola, WI, USA, ISBN 978-0-87938-763-1 .
- Robert N. Pripps, Andrew Morland: Ford Tractors: N-Series, Fordson, Ford and Ferguson, 1914–1954. MBI, 1990, Osceola, WI, USA, ISBN 978-0-87938-471-5 .
- Gerald Sandrieser: Fordson . Part 1: Fordson Tractors (1917–1964) . Klaus Rabe, Willich 2011, ISBN 978-3-926071-43-9 .
- Propylaea history of technology . Propylaeen, Berlin, 1990-1992, ISBN 3-549-07114-0 , Volume 5, p. 17 ff.
- Michael Bach in: Yearbook Tractors 2004 . Podzun-Motorbücher, Brilon 2003, ISBN 3-86133-333-3 , p. 5 ff.
- Troitsch / Weber (ed.): The technology - from the beginnings to the present . Westermann, Braunschweig 1982, ISBN 3-14-509012-7 , p. 371 ff.
- Albert Mößmer: Deutz-Bauernschlepper , GeraMond Verlag, Munich 2014, ISBN 978-3-86245-618-5 .
- Alexander Oertle, Jürgen Hummel: Type compass Deutz tractors 1927–1981 , ISBN 3-613-02385-7 .
- Karl Andresen: German tractors: data, facts, history. Delphin Verlag, 2018, ISBN 978-3-96128-268-5 .
- Albert Mößmer: Type atlas Deutz tractors: reference work on all models and types of the Deutz brand from steel tractor to agricultural machinery and tractors: technology, history, portraits. Geramond Verlag, Munich 2011, ISBN 3-86245-628-5 .
- Armin Bauer: Schlepper . Franckh-Kosmos, Stuttgart 2004, ISBN 3-440-09664-5 , p. 57 f.
- Horst Eichhorn (Ed.): Landtechnik . 7th edition, Ulmer, Stuttgart 1952/1999, ISBN 3-8001-1086-5 , p. 101 ff.
- cf. Rudi Heppe in: Yearbook Tractors 2004 . Posdzun, Brilon 2003, ISBN 3-86133-333-3 , p. 39.
- Horst Eichhorn (Ed.): Landtechnik . 7th edition, Ulmer, Stuttgart 1952/1999, ISBN 3-8001-1086-5 , p. 132.
- JOHN DEERE tractor series E-Premium
- Michael Kalcher in: Yearbook Tractors 2005 . Podzun-Motorbücher, Brilon 2004, ISBN 3-86133-362-7 , p. 51 ff.
- Horst Eichhorn (Ed.): Landtechnik . 7th edition, Ulmer, Stuttgart 1952/1999, ISBN 3-8001-1086-5 , p. 106 ff.
- Horst Eichhorn (Ed.): Landtechnik . 7th edition, Ulmer, Stuttgart 1952/1999, ISBN 3-8001-1086-5 , p. 236.
- The progressive farmer: AGCO / Fendt tire pressure control system for 900 Vario
- Norbert Uppenkamp: Low tire pressure protects the ground. Agricultural weekly paper Westphalia / Lippe 03/2004, pp. 46–48.
- Ed Gevers in: Yearbook Tractors 2005 . Podzun-Motorbücher, Brilon 2004, ISBN 3-86133-362-7 , p. 69 ff.