Expandable Trailers Repair

The fold-out bed deck is the whole engineering story on an expandable. It is a cantilevered platform hinged at the trailer end wall, supported at the outboard end by a cable, strut, or leg, and it carries two adults plus a mattress plus whatever else ends up on it. That load path runs through a hinge line at the root and a tension member at the tip, and both of those are components that owners never inspect. Cable ends corrode where they terminate, hinge fasteners elongate their holes in the end wall structure, and the deck substrate itself takes bending load it was never sized for once the support has stretched even slightly.

The substrate is the second issue and it is where most expandables end their useful life. Bed decks are typically plywood or a light composite, and they sit under a canvas or vinyl tent end that collects condensation. In Southern California mountain camping at Big Bear Lake or Idyllwild the overnight temperature drop puts real moisture inside that tent every night, and it runs down and collects at the deck edge where the tent attaches. A trailer folded and stored while that moisture is still present rots the deck from the outboard edge inward, and by the time it feels soft the hinge structure at the root has usually taken damage too from carrying load on a weakened panel.

Because the main body is hard-sided, an expandable is otherwise a conventional trailer with all of a conventional trailer problems. It has a laminated or stick-built sidewall, a ladder frame, tandem or single leaf spring axles, and a membrane roof. What it does not have is a rigid end wall in the usual sense, because both ends may be doorways for the bed decks. That reduces the racking resistance of the box, which is why expandables show more opening distortion at the entry door and windows than an equivalent fixed-wall travel trailer does.