Kart Other models

With an unladen weight of 2,500 kg, the dolly carries a payload of around 14,500 kg, almost six times its own weight. At 5.12 m long and 2.54 m wide, it is markedly shorter than an ordinary trailer, since its job is not to carry its own load but to transfer the axle load of the semi-trailer mounted on it.

Class O4 vehicles carry air brakes as standard, which on a dolly must be connected both to the mounted semi-trailer and to the towing vehicle. Driving a multi-unit combination like this requires licence category CE, and depending on the country, additional rules apply to multi-unit combinations. Trailers in this weight class also need rear underrun protection under UN/ECE Regulation R58, intended to reduce the severity of collisions where a car runs into the back of the trailer.

When buying a used dolly, it is worth checking the fifth wheel and drawbar eye for wear, since both parts carry the entire axle load of the mounted semi-trailer. Also worth checking are the brake system with its lines, the axle and wheel bearings for play, and whether the chassis number matches the registration papers. The rear underrun protection should additionally be checked for secure mounting and any deformation.