Abstract: A telescopically extensible vehicle trailer is disclosed having closely adjacent pairs of longitudinal main beams on each of the respective trailer sections with the main beams of one section disposed between and closely inwardly adjacent the main beams of the other section, and having a floating safety lock bar extending transversely between and carried by the longitudinal main beams of one of the sections cooperative with front and rear limit position stops on the other trailer section to avoid accidental separation of the sections if the conventional locking device therefor is not properly operated. A support mechanism for a coiled electrical cable and air hose system arranged to avoid long unsupported spans of cables and hoses is also disclosed.