Abstract: The invention relates to a support arrangement for a truck or trailer having a stationary side wall (2) and a maneuverable side member or wing (3). In order to avoid excessive stress on the side member (3) there is provided according to the invention a support arrangement which includes a substantially horizontal cantilever (12) which at one of its ends is secured to the stationary side wall (2) of the trailer and which at its other free end supports a bracket (15) in which two side member arms (9) and a side member support (10) positioned between the side member arms are rotatably mounted. The side member arms (9) are at their other ends rotatably mounted in the upper edge of the side member (3) and the side member support (10) is adapted to support the side member (3) with its free end when the side member is in its raised position.