Chassis for trailers or other vehicles

The undercarriage (6) has a support (18) arranged in an inner space between a longitudinal beam (11) and a cross beam of the undercarriage for supporting an aggregate (19) of a box-shaped structure (4) e.g. cooling case or camper structure. The undercarriage and the support comprise a defined interface for assembly and mutual adaptation of a connector arrangement. The support is connected with bottom (5) of the structure. A set of connectors is arranged at an upright bar (15) of the longitudinal and cross beams of the undercarriage. The aggregate is formed as an air conditioning apparatus or a heating apparatus. The longitudinal beam and the cross beam are formed as multiple breaks that are made of a metal sheet profile. The connector is formed as hooks or an aperture that is formed as slots or keyholes.