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Trailers in agriculture
Trailer for use on cars

A trailer is a vehicle that usually has a loading area to transport goods, but does not have its own drive. They are carried behind towing vehicles such as cars , trucks , buses , tractors , motorcycles (see motorcycle trailers ) or bicycles (see bicycle trailers ). Rail-bound trailers are called freight cars , wagons or lorries . As a rule, trailers are pulled, but in rail transport, trailers are also pushed.

Trailers are named and defined according to DIN 70010 (systematics of road vehicles). This is done in accordance with ISO 3833 , including tags and their technical characteristics. Trailers mainly transfer the load to the road via the wheels, with the exception of the vertical load on the towing vehicle - in the case of single-axle trailers . The tractive forces are transferred from the towing vehicle to the trailer via the so-called drawbar . A trailer coupling is used for the connection between the towing vehicle and a trailer or the connection between trailers when several trailers are coupled to the towing vehicle.


The following trailers are mentioned for basic designs:

  1. Rigid drawbar trailer
  2. Articulated drawbar trailer
  3. Semi-trailer
  4. Special designs

Rigid drawbar trailer

With rigid drawbar trailers (SDAH), the drawbar is rigidly connected to the trailer frame. It has one or two axles (less often three), which are also rigidly connected to the frame . Almost all car trailers are built as rigid drawbar trailers. In Germany, according to the StVZO harmonized in the EU , as in Austria, such a trailer with a gross vehicle weight of up to 750 kg (GVW) is considered a light trailer and does not need its own brake. A brake is required from this total weight. In Europe this is usually an overrun brake . Overrun brakes are permitted up to a gross vehicle weight of 3500 kg. Heavier trailers require a continuous braking system, this is almost always an air brake .

Most caravans , boat trailers and motorcycle transport trailers are rigid drawbar trailers with one axle or one tandem axle. Special trailers are, for example, horse trailers , which are mainly designed as tandem trailers. Depending on the application, various suspension systems are offered here, such as rubber spring axles , torsion bar spring axles, torsional thrust spring axles and coil springs.

If two axles are built close together on a trailer, the driving behavior is similar to that of a single-axle trailer. Such trailers do not need a turntable - the drawbar is firmly connected to the trailer chassis and both axles are not steerable. This is paid for with higher tire wear in tight curve radii. If the axes are less than 1 m apart, they are considered uniaxial in Germany according to the law; the term tandem trailer has established itself for this. This has no influence on the toll , because every visible axis counts here. However, the tandem axle must be taken into account in the driving license regulations. B. With the old German car driving license of class 3, a truck with up to 7.5 t and a single-axle trailer with up to 11 t axle load can be driven.

Articulated drawbar trailer

These trailers have two or more axes, one of which (hence the front axle via a turntable bogie trailer called) or unusual with individually directed stub axle is steered. These trailers are typical of trucks and tractors . Car trailers of this type have recently been offered for light long or high volume transports. The permissible total weight is up to 20 tons for two axles and 24 tons for three axles - with a special permit ( low-loader for heavy transports) above this.

With turntable steering, the front axle is mounted on a turntable and firmly connected to the drawbar. The drawbar can be moved vertically and is held in place with strong springs as a safety precaution. It must not touch the ground after uncoupling. Multi-axle trailers over 3500 kg GVW must be equipped with a compressed air brake.

Similar to the truck , the body types are very versatile. Typical construction types are the open box (flatbed), the open box with tarpaulin and bow and the closed box ( box body ). There are also many special designs that are adapted to the respective purpose.


The semitrailer, usually called a semitrailer , does not have a front axle, but rests with its front part on the tractor unit . Together with the tractor unit, it forms the articulated vehicle . For some years now, the semi-trailer has been provided with a dolly front axle (with a special permit) so that it can be attached to the EuroCombi in the EEA countries .

Special forms

Road scooter with tank car
  • The road scooter (colloquially Culemeyer ) is a vehicle trailer developed by Johann Culemeyer in 1931 for the transport of railroad cars and heavy loads on the road. This multi-axle trailer was available in different designs with different payloads.
  • A trailer is called a trailer that is used for particularly long goods, such as logs or prefabricated components. When loaded, the trailer is usually connected to the towing vehicle with a central pipe, a wire rope or only through the load.
  • Light motor vehicles with a jacked up axle are towed on a towing axle. It is unloaded like a single-axle trailer, loaded like a multi-axle trailer.
  • Push trailers have their own motorization, mostly for vehicles with a weak drive of their own, for example bicycles and mopeds. You are not eligible for admission in Germany.

Legal regulations in Germany

Load types, dimensions and weights

Total mass
Such is the mass that is calculated from the sum of all axle loads of the individual vehicles (uncoupled). The permissible total mass is relevant for the question of the correct driving license and the type of braking system. The maximum total mass of a tandem trailer (axle spacing less than 1 m) may have 11 t, a two-axle trailer may have 20 t and a three-axle trailer 24 t.
Vertical load
The vertical load is the load that is placed on the trailer coupling when it is coupled. In general, the higher the vertical load, the better the handling. However, the maximum permissible support load of the coupling must not be exceeded. With a permissible total weight of no more than 3.5 t, the minimum vertical load must not be less than 4 percent of the actual total weight of the trailer, but it need not be more than 25 kg.
Trailer load
The trailer load is the actual load regardless of the maximum permissible gross weight. In the case of single-axle trailers without a bogie, the vertical load is part of the vehicle load. The trailer load is therefore the actual total mass of the trailer minus the vertical load. For example, if the towing vehicle has a permissible trailer load of 1200 kg, a trailer with a mass of 1250 kg may be attached if the vertical load is 50 kg and this is within the vertical load range permitted for the trailer coupling.
Length, width and height
The total length of a trailer must not exceed 12 m, the width 2.55 m and the height 4 m.

Chassis and suspension

For trailers, the oldest and most common type of chassis is the ladder frame attached to the rigid axles . The undamped design of the rigid axle can be found in older trailers in agriculture and forestry as well as in light transport trailers to this day. The most widespread of the sprung axle is leaf suspension , which is designed as a parabolic or trapezoidal suspension . In recent times this has increasingly been replaced by independent wheel suspension and air suspension (roll bellows). The first vibration dampers were scissor dampers, more recently hydraulic shock absorbers in connection with the rolling bellows have become the state of the art.



The first trailers were not equipped with their own brakes. In 1908, with the regulations on subsidy trucks and the advent of trucks , brakes were required to sit on the trailer and apply the trailer's block brake . In 1913 there was no longer any need to brake on the trailer and in 1915 the standard 3-tonne truck became the predominant type of truck in Germany. Until after the First World War , trailers normally did not have their own service brake. The number of trailers was not limited either, so that by 1925 trucks with up to four trailers were put into operation. The maximum speed for heavy trucks (over 5.5 t) with trailers was limited to 16 km / h in urban areas and 25 km / h in rural areas.

On January 1, 1926, with the introduction of the new regulation on motor vehicle traffic , the permissible weight was limited to 7.5 t and the number of trailers to one. The trailer - if more than one axle - had to have its own service brake from 1926; technically, this was not a problem, as the Knorr air brake was introduced in 1923. The overrun brake, on the other hand, was only introduced for light trailers in 1936, and in the first StVZO from 1937 it was subject to approval for a maximum permissible weight of over 5.5 t or over 20 km / h. Two trailers with overrun brakes were not permitted. Due to a circular in the Second World War of June 15, 1940 (RGBl. P. 220), two trailers with overrun brakes could now be carried behind motor vehicles (trucks) .

It was not until November 25, 1951, that the StVZO was reset to its pre-war status. In the same year, with the introduction of the non-return valve on the compressed air brake system, the total breakdown of the towing vehicle's brakes was prevented if the trailer was lost. In the 1960s, ATE offered the "Hydrakup", a hydraulic braking system for caravans. The hydraulic brake system of the car was connected to the trailer via two coupling parts (motor vehicle and trailer coupling head); the braking effect of the trailer's drum brakes started with the towing vehicle. In 1967 Daimler-Benz introduced the spring-loaded brake for the parking brake on air-braked trailers.

For trailers over 25 km / h bbH, regulation 71/320 / EEC of July 30, 1971 stipulated the dual-line brake, which had to be implemented on January 30, 1973. In the single-line system, which works with a maximum system pressure of 5.3 bar, the trailer is connected via a control line that simultaneously fills the trailer's air tank. This does not replenish the trailer's air supply when braking. The braking force is considerably reduced in the case of long downhill stretches or if there is a leak. 1981 Daimler-Benz introduced WABCO - anti-lock brakes on a truck trailer. As of January 1, 1991, an EC brake system according to Directive 71/320 / EEC was mandatory, which had to have two brake circuits and a load-dependent brake force regulator . Since January 1, 2001, an automatic anti-lock device has been prescribed for newly registered trailers over 3.5 t.

Current regulations

up to 750 kg
No separate brake required.
up to 3500 kg
Overrun brake permitted. At a maximum speed of 25 km / h up to 8000 kg GVW permitted; up to 40 km / h with an overrun brake on each wheel. Overrun brakes are not permitted on semitrailers. Two trailers with a gross vehicle weight of up to 8000 kg each with an overrun brake are permitted behind tractors if the maximum speed is 25 km / h.
over 3500 kg
Dual line compressed air braking system prescribed. These trailers must also be equipped with an anti-lock braking system if the maximum speed is over 60 km / h .
over 9000 kg
Trailers must be equipped with a permanent brake (service brake), the braking power of which corresponds to driving a gradient of 7 percent and a length of 6 km with the fully loaded vehicle at a speed of 30 km / h.

Wheel chocks

Trailers must be equipped with wheel chocks . A wheel chock is required for two-axle trailers (except for semi-trailer and rigid drawbar trailers) over 750 kg gross vehicle weight. Two wheel chocks require three- and multi-axle vehicles, semitrailers, rigid drawbar trailers over 750 kg GVW.


Pin coupling
The first detachable trailer hitches are known from 1904, but a "trailer industry" did not emerge until 1912. In the 1920s, different coupling systems were used; In 1925 alone, 17 different pin couplings were counted. Simple pin couplings are still used for unbraked trailers in agriculture, forestry and construction sites.
Jaw coupling
The manufacturer Rockinger developed an automatic jaw coupling in 1927, for which he received a US patent in 1932. The manufacturer Ringfeder from Uerdingen produced a similar product for the railway sector as early as 1923 . These systems of the automatic closing process, in which no person has to be between the towing vehicle and the trailer during the coupling process - this is strictly forbidden according to today's accident prevention regulations - are becoming established worldwide in the commercial vehicle sector. Open-ended couplings in the truck sector with an eye diameter of 50 mm achieve D values ​​of 200  kN and D c values ​​of 135 kN. In agriculture and forestry with an eyelet diameter of 40 mm, the D value is 120 kN.
Fifth wheel
For the semi-trailer , a is fifth wheel with king pin required. The first patents for a detachable semi-trailer were granted in 1932, but the first articulated truck was introduced as early as the 1920s with the “Oekonom large area wagon”.
Ball coupling
Detachable ball quick-release fasteners were already being offered by motorcycle combinations in the early 1930s . On March 14, 1934, Franz Knöbel received a patent for the ball head coupling. With this invention, the manufacturer Westfalia achieved worldwide fame. The ball head diameter of 50 mm at that time is still the norm for cars today. For trailers (without / with overrun brake) the ball head coupling is the coupling standard today. The non-“automatic” ball head coupling is permitted for trailers in agriculture and forestry - a ball with a diameter of 80 mm and a D-value of 90 kN is common there - and for trailers with a weight of less than 3500 kg.

Electrical and mechanical connections


The same lighting regulations apply to trailers as to all motor vehicles. The trailer must have tail lights , brake lights and indicators , as well as one or two rear fog lights . One or two reversing lights can be attached. The lighting is supplied with power from the towing vehicle. The connector is either 7- or 13-pin and is standardized. Details can be found in the article trailer socket .


Detachable trailer hitches can be found in the area of ​​the ball head coupling. If the drawbar load is over 50 kg, a height-adjustable support device is required for rigid-drawbar trailers , which must be housed “captive”.

With the jaw and fifth wheel coupling, the braking force is transmitted by compressed air. The supply line (red) and the brake line (yellow), like the electrical connections, must be connected to the towing vehicle. If the supply line is not connected, the trailer control valve will not open. If the supply line breaks while driving, the trailer brake valve triggers full braking of the trailer.

Breakaway rope

The use of a breakaway cable is mandatory for trailers with overrun brakes . This is connected to the trailer brake mechanism and is attached to the towing vehicle's ball head coupling using a loop and snap hook. As soon as the trailer should unexpectedly detach itself from the towing vehicle while driving, the brake of the trailer is activated so that it quickly comes to a standstill independently.

Reflectors and reflectors

Two stern marker boards
Old trailer triangle

For all trailers, two red, reflective triangles ( rear reflectors ) are required at the rear , which must be fitted with a point pointing upwards. The equilateral triangles must have an edge length of at least 15 cm. Yellow, non-triangular reflectors are required on the side, and yellow side marker lights are required from a trailer length of 6 meters. Trailers with a width of more than 2.1 m must have white clearance lights to the front and red clearance lights to the rear.

Stern marking boards

For trailers of the EU vehicle classes O3 and O4 (with a permissible total weight of more than 3.5 tonnes), rear marker boards, which in accordance with ECE No. 70 are contour markings, are required from the first registration on July 10, 2011. The purpose of the regulation is to draw the attention of the following passengers to the train, as a longer overtaking distance must be expected when overtaking . One, two or four boards can be used; they must be rectangular, have a yellow reflective background and a red reflective border. The length of the rear identification plate must be between 113 and 230 cm and the width 20 cm.

Trailer triangle

The trailer triangle was prescribed in Germany ( German Reich and then in the FRG and the GDR ) from April 1, 1938 to 1956 according to Section 44 of the StVZO . It was foldable and the yellow area was illuminated inside. There was also a corresponding regulation in Austria .

In Denmark there have been / have been warning signs on cars at the level of the front wheel since around / around 1990 to indicate to cyclists that a trailer is following.

Registration and driving license rights for car trailers

Trailer without its own brake, 750 kg
Trailer with its own brake (overrun brake) 2.6 t

With all trailers, it must be ensured that the mass of the trailer and that of the towing vehicle are matched to each other and comply with the law .

Situation in Germany

  • With the overrun brake, the trailer load must not exceed the maximum permissible mass of the towing vehicle.
  • An exception applies to certain cars that are off-road vehicles according to 70/156 / EEC; these may tow trailers with a maximum mass up to 1½ times the permissible total mass of the towing vehicle.
  • If a continuous compressed air brake system is available, the maximum total mass of the trailer may be 1½ times that of the tractor - except for agricultural trailers, where up to four times the net weight of the tractor is permitted.

Car trailers with a gross vehicle weight of up to 750 kg

The actual total mass of the trailer must not exceed the permissible towing mass (unbraked) of the towing vehicle. In the case of single-axle unbraked trailers, according to Section 42 (2) StVZO, this is “at most half of the unladen weight of the towing vehicle increased by 75 kg, but not more than 750 kg”. These trailers usually do not have their own brake.

Car trailers with a gross vehicle weight of over 750 kg

These trailers must have their own brake. The trailer load (i.e. the total mass of the trailer minus the vertical load) of the trailer with the overrun brakes may exceed the empty weight of the towing vehicle, but not the permissible total mass of the towing vehicle and not the maximum trailer load specified in the vehicle registration document. Exceptions are off-road vehicles, here the actual trailer load of the trailer may be 1.5 times the permissible total mass of the towing vehicle, but only a maximum of 3.5 t and a maximum of the maximum trailer load specified in the vehicle registration document.

Driving license class B

On towing vehicles that fall into driving license class B (up to 3.5 t), a trailer with a maximum permissible total weight of 750 kg may be carried with this driving license class (maximum gross vehicle weight 4.25 t). If the permissible total mass of the trailer is greater than 750 kg, the permissible total mass of the combination may only be 3.5 t.

Driving license class B with code number 96

With the driving license class B with code number 96 (also B96 ) the permissible total weight of the trailer may exceed 750 kg. In contrast to class B, the permissible total weight of the combination can be up to 4.25 t. The regulation has been in effect since January 19, 2013.

Driving license class BE

The "E" in the respective driver's license classes indicates that vehicle-trailer combinations may be driven. In the case of a car driver's license, an "E" is added to class B accordingly. It is no different with driving licenses for buses or trucks with trailer authorization: Here it is called C1E, CE, D1E or DE. With the driving license class BE, the permissible total weight of the trailer may be up to 3.5 t. If the total mass of the trailer is more than 3.5 t, class C1E is required

Driving license class BE (January 1, 1999 to January 18, 2013)

From January 1, 1999 to January 18, 2013, the maximum permissible mass of the trailer and the entire train in the BE class was not limited. Driving licenses issued during this period enjoy grandfathering in this regard. If the driver's license is exchanged after January 18, 2013, the code number 79.06 is entered for the BE class. Since the classes C1E, CE, D1E, DE include the class BE, the class BE with code number 79.06 is also entered for these when they are exchanged.


The former German driving license of class 3 (cars with trailers) stipulated that only single-axle trailers were allowed to be towed, whereby tandem-axle trailers were considered single-axle vehicles if the distance between axles was less than one meter. This number of axles no longer applies to the current EU driving license law.

100 km / h approval

Tempo 100 badge
Trailer with overrun brake and shock absorber (100 km / h approval)

In Germany, a maximum speed of 80 km / h applies to trailers. Certain cars with trailers, certain multi-lane vehicles with a gross vehicle weight of up to 3.5 t and 100 km / h-approved buses with a gross vehicle weight of up to 3.5 t with a trailer may, in deviation from Section 18 (5) No. 1 StVO drive up to 100 km / h on motorways and motorways.

The vehicle combinations must meet the following requirements for this:

  • Towing vehicle with ABS in connection with a trailer without brakes or a trailer with brakes but without hydraulic shock absorbers:
    permissible mass of the trailer ≤ 0.3 × empty mass of the towing vehicle
  • Towing vehicle with ABS in connection with caravan with brakes and hydraulic shock absorbers:
    permissible mass of the trailer ≤ 0.8 × empty mass of the towing vehicle or also ≤ 1.0 × empty mass of the towing vehicle, if equipped with a ball coupling with roll
    damping according to ISO 11555-1 or with equipped with another technical device, through which the operation of the combination up to 120 km / h is proven by means of a parts certificate / ABE
  • Towing vehicle with ABS in connection with another trailer (e.g. horse trailer ) with brakes and hydraulic shock absorbers:
    permissible mass of the trailer ≤ 1.1 × empty mass of the towing vehicle or also ≤ 1.2 × empty mass of the towing vehicle, if with a roll clutch according to ISO 11555-1 or provided with another technical device through which the operation of the combination up to 120 km / h is proven by means of a parts certificate / ABE

The following also applies to all types of combination:

  • permissible mass of the trailer ≤ permissible mass of the towing vehicle
  • permissible mass of the trailer ≤ permissible trailer load according to vehicle registration document
  • Tires of the trailer has for 100 km / h no surcharge to load index received
  • The trailer tires correspond at least to the speed category L (= 120 km / h)
  • The trailer's tires are less than 6 years old, recognizable by the stamped date of manufacture ; Note the calendar week
  • The 100 badge sealed by the office must be visible on the back of the trailer.

The mass information can be found in the entries in the vehicle registration documents (empty mass: Section 14, permissible mass: Section 15, or fields G and F.1 / F.2 in the new registration certificate, Part I).

The 100 km / h approval is regulated in the “Ninth Ordinance on Exceptions to the Road Traffic Regulations ”. The limitation of the regulation until December 31, 2010 has been lifted. It therefore continues to apply indefinitely.

NAG 5000 S with two trailers

Multiple trailers

On January 1, 1938, the new StVZO allowed a maximum train length of 22 m in Germany ; this meant that up to two trailers could be carried behind the truck. On November 25, 1951, the StVZO was reset to the pre-war status (no two overrun braked trailers) and on April 1, 1953 the second trailer for trucks was banned.

Currently, two trailers can only be carried behind tractors if the following rules are observed:

  • the first trailer must not have more than two axles
  • the total length of the vehicle train must not exceed 18.75 meters ( Section 32 Paragraph 4 No. 3 StVZO)
  • the total mass is a maximum of 40 tons

In the USA or Australia , truck rails or road trains are common, trucks with several trailers. However, the road trains are not allowed to drive into cities and have to uncouple the trailers except for one at the city limits.

Bus trailer for city ​​traffic

Passenger transportation

Nobody is allowed to be taken on the loading area or in the hold of trailers. However, if trailers are used for agricultural or forestry purposes, people may be taken along in suitable seating. Caravans are trailers and, in terms of passenger transport, are treated as such.

According to Section 46 of the StVO, local road traffic authorities can temporarily and subject to certain conditions lift the ban on the transport of people on trailers.

Bus trailers that are intended for passenger transport are usually coupled with buses . Bus trains with trailers are particularly common in Swiss cities. In Germany, after a ban on the use of bus trailers in the early 1960s, it has been possible to operate bus trailers with special permits again for several years.


  • Heribert Braun, Günter Kolb: Truck. A textbook and reference work. 11th edition, Kirschbaum-Verlag, Bonn 2012, ISBN 978-3-7812-1850-5 .
  • Erich Hoepke, Stefan Breuer (Ed.): Commercial vehicle technology: Fundamentals, systems, components. 7th edition, Vieweg & Teubner, 2012, ISBN 978-3-8348-1795-2 .

Web links

Commons : Trailers  - collection of images, videos and audio files


  1. For trailers over 20 km / h maximum speed and up to 5.5 t GVW, from January 1, 1938 to April 1, 1953, an overrun brake that acted on one axle was permitted according to § 41 StVZO.
  2. In the case of semi-trailers, measurements are taken from the kingpin to the rear limit, the front overhang radius is 2.04 m.
  3. § 25 (4) Ordinance on Motor Vehicle Traffic of December 5, 1925 permitted exemptions from the police authorities requiring approval. In contrast to tractors in agriculture and forestry, the regulation was applied restrictively for trucks.
  4. The air compressor was designed so that the operating pressure could be reached in 3 minutes at the latest, but not when the retarder was applied . The brake circuit was deemed to be sufficiently tight if the pressure drop within 10 minutes with the engine switched off was not greater than 0.1 bar. See single-line single-circuit air brake system with permanent brake. Explanation by F. and W. Rauscher, self-published by Freising, February 1976.
  5. While longitudinal play of the drawbar is not permitted, the wear limit of the drawbar eye is 1.5 mm (40 mm drawbar eye) and 2.5 mm (50 mm drawbar eye). The bushing of the towing eye is exchangeable and is not welded, but "rolled up".
  6. Before 1926 there were no regulations regarding train length; In the intermediate phase from 1926 to 1938 the train was limited to one trailer and the train weight to 22.5 t GVW.

Individual evidence

  1. Trailer: A vehicle without its own drive for the transport of goods, which is intended for coupling to a motor vehicle, with the exception of a trailer . (Definition of the European Conference of Transport Ministers, Federal Law Gazette 2015 II pp. 69, 72 )
  2. Commercial vehicle technology: Fundamentals, systems, components , p. 19.
  3. See § 34 (4) No. 3 StVZO (double axle load of trailers with an axle distance of less than 1.0 m = 11 t.)
  4. See § 34 (4) No. 3.4 StVZO.
  5. See § 43 (1) StVZO.
  6. See § 34 (4) StVZO.
  7. See § 44 (3) StVZO.
  8. See § 32 StVZO.
  9. Heribert Braun, Günter Kolb: Lkw. P. 94
  10. Jürgen Helling and Heinz Junker: Chassis and suspension . In: Olaf von Fersen : A Century of Automotive Technology - Commercial Vehicles. VDI-Verlag, Düsseldorf 1987, ISBN 3-18-400656-6 , p. 164 ff.
  11. See four-train cars from Daimler. In: Olaf von Fersen : A Century of Automotive Technology - Commercial Vehicles. VDI-Verlag, Düsseldorf 1987, ISBN 3-18-400656-6 , p. 198.
  12. See Section 18 of the Ordinance on Motor Vehicle Traffic of December 5, 1925.
  13. ^ Olaf von Fersen: A century of automobile technology - commercial vehicles. VDI-Verlag, Düsseldorf 1987, p. 200.
  14. ^ Olaf von Fersen: A century of automobile technology - commercial vehicles. VDI-Verlag, Düsseldorf 1987, p. 202.
  15. Stopfix overrun brake, patent DE652285C from May 10, 1935.
  16. § 41 (6) StVZO of November 13, 1937.
  17. § 41 (6) StVZO; Circular of June 15, 1940.
  18. Textbook for drivers , Volume 134, 4th edition, Degener Verlag, Hannover 1962, p. 148.
  19. Hydrakup (accessed April 7, 2014)
  20. 71/320 / EEC
  21. Official Journal 71/320 / EEC (PDF)
  22. ^ Erich Schwelk, Walter Lohmüller, Hermann Strobel: Fachkunde Kraftfahrtechnik , Holland-Josenhans-Verlag, 2nd edition, Stuttgart 1982, ISBN 3-7782-3520-6 , p. 287.
  23. ^ Olaf von Fersen: A century of automobile technology - commercial vehicles. VDI-Verlag, Düsseldorf 1987, pp. 208, 212.
  24. See § 72 entry into force and transitional provisions to § 41b (5) StVZO.
  25. See § 41 (11) StVZO.
  26. See § 41 (10) No. 2 StVZO.
  27. See § 41 (10-11) StVZO.
  28. See § 41b (2) No. 2 StVZO.
  29. See § 41 (15) StVZO.
  30. See § 41 (14) StVZO.
  31. ^ Olaf von Fersen: A century of automobile technology - commercial vehicles. VDI-Verlag, Düsseldorf 1987, p. 264.
  32. Castner: Accident-proof couplings for trucks. In: Polytechnisches Journal . 341, 1926, pp. 141-144.
  33. ^ Jost-World history Rockinger (accessed on March 26, 2014)
  34. U.S. Patent 1939463
  35. ( Memento from March 28, 2014 in the Internet Archive ) Ankuppeln (accessed on March 26, 2014)
  36. Coupling process around 1925 - strictly prohibited today
  37. See Ringfeder type 5050 EC 11 94/20
  38. U.S. Patent 1990700
  39. Oekonom large area trolley
  40. from March 15, 2014 ( Memento from March 25, 2014 in the Internet Archive ) Westfalia Automotive GmbH celebrates the trailer coupling - patent certificate issued 80 years ago (accessed on March 25, 2014)
  41. Cf. Rockinger  ( page no longer available , search in web archivesInfo: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.@1@ 2Template: Toter Link /  
  42. See § 43 (4) StVZO.
  43. See § 49a StVZO.
  44. See § 52a (2) StVZO.
  45. See § 44 (2) StVZO.
  46. § 41 StVZO paragraph 9 sentence 4
  47. See § 53 (4) StVZO.
  48. See § 51a (1) StVZO.
  49. See § 51b (2) StVZO.
  50. Heribert Braun, Günter Kolb: Lkw. P. 417.
  51. See Appendix 5 of ECE Regulation No. 70 of May 15, 1987.
  52. See § 44 StVZO of November 13, 1937.
  53. The driving license classes . Retrieved June 29, 2020.
  54. See § 6 FeV (1).
  55. See Appendix 3 FeV II. No. 5 i. V. m. Appendix 9 FeV BI No. 129
  56. See Annex 3 FeV II. No. 5
  57. 9th Exemption Ordinance on the Road Traffic Act of October 15, 1998 (accessed on March 28, 2014)
  58. Limitation of the 9th Exemption Ordinance to the StVO
  59. See § 21 (2) StVO