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DGT Glossary
CC1D

Tractor unit

Motor vehicle built mainly to haul a semi-trailer; coupled to one it forms an articulated vehicle.

Definition

A tractor unit (tractocamión) is the vehicle Spain's Reglamento General de Vehículos defines as designed and built mainly to haul a semi-trailer. It is the tractive unit on its own: it does not carry the load, it pulls it on its fifth wheel. Once the semi-trailer is coupled, the combination becomes an articulated vehicle — a motor vehicle coupled to a semi-trailer — and also counts as a combination of vehicles under the traffic rules.

Tractor unit, articulated vehicle and road train

Three words for three different things. The tractor unit is the motor vehicle alone. An articulated vehicle is that tractor unit with a semi-trailer coupled to it. A road train (tren de carretera) is a motor vehicle with a full trailer hitched instead. Neither the tractor unit nor the road train belongs to the special-vehicle group — an agricultural tractor does. Their speed limit is 90 km/h on motorways and dual carriageways and 80 km/h on conventional roads.

Key facts

  • The tractive unit: it hauls the semi-trailer rather than carrying the load.
  • Tractor unit + semi-trailer = articulated vehicle, treated as a combination of vehicles.
  • With a full trailer instead, the combination is a road train.
  • Not a special vehicle; 90 km/h on motorways, 80 km/h on conventional roads.

Keep studying

Frequently asked questions

What is a tractocamión?
The motor vehicle designed and built mainly to haul a semi-trailer — the tractor unit. It does not carry the load itself.
What is the difference between a tractor unit and an articulated vehicle?
The tractor unit is the motor vehicle alone; the articulated vehicle is that unit with a semi-trailer coupled to it.

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