Tractorheads
A tractorhead (tractor unit) is the motorised vehicle designed to haul semi-trailers in road freight transport. It is the backbone of European international haulage, with configurations ranging from the standard 4x2 for highway use to 6x4 for heavy-duty applications.
Tractorheads by brand
The European tractor unit market is dominated by seven major manufacturers, each with distinctive characteristics:
- Renault Trucks: The T range (460, 480, 520 HP) with DTI 11 and DTI 13 engines excels in fuel efficiency. The T High versión offers a raised cab for maximum long-haul comfort. The Optidriver automated transmission is among the smoothest on the market.
- DAF: The XF and CF series with 12.9-litre PACCAR MX engines are a benchmark in reliability. The XF 510 is one of the most sought-after vehicles in international transport. The new XG+ sets a new standard in interior space.
- Mercedes-Benz: The Actros features MirrorCam technology (cameras replacing mirrors), Active Brake Assist 5 and Predictive Powertrain Control that adjusts driving to the terrain. The OM 471 12.8L engine delivers 421 to 530 HP.
- Volvo: The FH series with I-Shift transmission is the benchmark in active safety. D13 13-litre engines offer 420 to 540 HP. The regenerative braking system and Volvo Dynamic Steering reduce fatigue and fuel consumption.
- Scania: The R and S series use 13 and 16-litre (V8) engines with outputs up to 770 HP. The Opticruise transmission and Scania's own retarder are considered the best in the industry. Scania also excels in predictive maintenance programmes.
- MAN: The TGX series with D26 (12.4L) and D38 (15.2L) engines offers robustness and durability. The MAN EfficientCruise system uses GPS and topographic data to optimise fuel consumption.
- Iveco: The S-Way (successor to the Stralis) is powered by Cursor 11 and Cursor 13 engines delivering 400 to 570 HP. Iveco pioneered LNG (Liquefied Natural Gas) with the Stralis NP, offering ranges of up to 1,600 km on gas.
Retarder and braking systems
A retarder is an auxiliary electromagnetic or hydrodynamic braking system fitted to the driveline. It reduces service brake wear by up to 90% on mountain routes, significantly improving safety and reducing maintenance costs. The main types are the hydrodynamic retarder (Voith, ZF), the intarder integrated into the gearbox (ZF, Mercedes) and the engine brake with exhaust valve (Jake Brake). For long-distance international transport, a retarder is practically essential.
Power take-off (PTO) and hydraulics
The power take-off transmits engine power to auxiliary equipment such as hydraulic pumps, compressors or generators. It is essential for tractor units working with tipper trailers, pressure-discharge tankers or refrigeration units. The most common configurations are gearbox-dependent PTO (only works with the vehicle stationary) and engine-independent PTO (works while driving).
Euro emission standards
Euro standards regulate pollutant emissions from heavy vehicles in the European Union. Euro 6 (in force since 2014) requires post-treatment systems such as SCR (Selective Catalytic Reduction) with AdBlue and DPF particulate filters. Euro 5 and earlier vehicles face circulation restrictions in low-emission zones (LEZ) in European cities. The upcoming Euro 7, planned for 2027, will further tighten NOx and particulate limits.
Axle configuration
The standard configuration for long-distance transport is 4x2 (two axles, rear-wheel drive), offering the lowest kerb weight and fuel consumption. For more demanding applications, 6x2 (three axles, one steered) is ideal when greater payload is needed. The 6x4 (three axles, twin drive) is used in construction and off-road, as is the 4x4 for full off-road capability.