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Trailers, couplings and the load

What each trailer body is for, how tractor and trailer fit together, the dimensions they must keep, and the rules for loads that need more than a tarpaulin.

11 articles

What is a semi truck? Tractor unit, semi-trailer and trailer definedA semi truck is a tractor unit coupled to a semi-trailer. How EU, UN, US, British, Turkish and Spanish texts define the tractor, the semi-trailer, the trailer and the combination.8 October 2026 · 12 sources
Trailer types explained: what each semi-trailer body carriesCurtainsider, box, reefer, tipper, silo, skeletal and low loader — what each semi-trailer body is for, and what the choice costs in tare weight and payload.29 September 2026 · 25 sources
Kingpin and fifth wheel: what makes a tractor and a semi-trailer compatibleCoupling class, the D value, the imposed load U and the coupling height are the four figures that decide whether a tractor will pull a given semi-trailer, and where each one is found.25 September 2026 · 10 sources
Semi-trailer dimensions: the rules around the 13.62-metre deckKrone and Schmitz Cargobull both publish a 13,620 mm curtainsider deck. The EU rule that bounds it, Annex I 1.6 of Directive 96/53/EC, is measured from the kingpin, not end to end.24 September 2026 · 12 sources
Swap bodies (Wechselbrücke) explained: what they are, and how they differ from semi-trailers and containersA swap body is a freight unit optimised to road vehicle dimensions, with handling devices for transfer between modes. What the glossary, EN 284 entries and makers' data sheets say.19 October 2026 · 21 sources
Trailer brakes and EBS: what the rules require of an O3 or O4 semi-trailerContinuous braking, anti-lock and a pressure test connection downstream of the control line coupling head: what UN Regulation No. 13 asks of a heavy trailer, and why a mismatched pair brakes badly.25 September 2026 · 5 sources
Load securing: the forces the rules assume and the standards behind themAnnex III of Directive 2014/47/EU gives a yardstick a roadside cargo check may use: 0.8 of the cargo weight forward and 0.5 sideways and rearward. What the figures mean and who answers for them.24 September 2026 · 12 sources
ADR explained: dangerous goods vehicles, orange plates and tunnel codesWhat makes a trailer an ADR trailer under ADR 2025 — the EX/II, EX/III, FL and AT designations, the approval certificate, the orange plate and the tunnel restriction code.25 September 2026 · 6 sources
Refrigerated transport: temperature records and the ATP insulation testRegulation (EC) No 37/2005 makes the food operator record air temperature and keep the record for at least a year. The ATP imposes almost the same duty, and adds the K test.25 September 2026 · 8 sources
Semi-truck dimensions: the federal length, width and height rulesHow long, wide and tall a semi-truck may be in the US: the 48-foot and 28-foot trailer minimums, no overall length limit on the National Network, 102 inches wide, State height limits.30 September 2026 · 2 sources
How many pallets fit in a trailer: Euro pallets, 48 x 40s and the arithmeticEuro pallets on a European semi-trailer with a 13,620 mm floor and 48 x 40 inch pallets in a 53-foot US dry van: the footprints, the makers' load-space figures, what fits.19 October 2026 · 8 sources