Dolly (trailer)

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Two-axle dolly with fifth wheel attached to the towing vehicle

A dolly (engl. Dolly ) is a short trailers , consisting of one to three axes, and a fifth wheel coupling for receiving a trailer .

principle

Dolly and trailer
Dolly in use with a semi-trailer

The dolly front axle serves as a special trailer for coupling one or more semi-trailers to a towing vehicle , which therefore does not have to have its own fifth wheel. Longer commercial vehicle combinations ( EuroCombi , Road Train , LZV , LCV ) with trailers can thus be formed with conventional semitrailers without great effort, as are common in the USA , Australia , Russia , Finland and Sweden, for example . Dollys are also increasingly being used in agriculture to pull truck trailers with tractors.

The air-sprung dolly front axle runner has been in use in the states of the European Economic Area since 1970 and has been widely used since 1996 thanks to EU Directive 96/53 / EC.

Dollys are also used in some companies to maneuver semi-trailers. This means that three trailers can be used with just one tractor unit in factory traffic, which saves waiting times. The first is being loaded, the second is being unloaded at the same time and the third is on its way to the loading or unloading point. So that the loading ramps are not blocked by trailers that have already been processed, a tractor is used, for example , to move the trailer with the dolly and trailer to a parking space. This means that after the trailer has been replaced, transport can start again after just a few minutes.

Constructive and manufacturer

In Germany, Fahrzeugwerk Krone , Schmitz Cargobull , Fliegl Fahrzeugbau and Bergischeachsefabrik (BPW) are currently building this front axle runner for the semi-trailers in order to be able to use the EuroCombi optimally. The BOKraft circle and the roundabout on public roads can only be used with the EuroCombi variant A if the dolly is also steered.

steerable dolly for the EuroCombi trailer

So far, the EuroCombi has erased 40 to 45 cm in the required inner radius of 5.30 meters. A steering reduction of the air-sprung dolly double front axle runner can now be activated electronically up to 30 km / h and allows it to run down to an inner radius of around 5.70 to 5.80 meters, making it roll cleanly behind the towing vehicle and less sharply inside through the standard Kreisel drives as a 13.60 meter long standard saddle. This steering impulse is electronically automated at BPW and mechanically at Krone by the turning movement of the dolly trailer opposite to the motor vehicle and allows the dolly to drive outwards in accordance with standards.

Notes and sources

Individual evidence

  1. ↑ EU Directive 96/53 / EC (PDF file; 1.0 MB)
  2. ↑ § 32d StVZO

See also