the present invention is related to a piston - cylinder mechanism for the pivoting or tilting of the platform of a vehicle mounted goods elevator between a raised resting position and a lowered working position , including at least one piston rod slidably movable relative to a piston in the mechanism and uniformly movable by means of a driver together with the piston between a bottom position wherein the platform is lowered and an intermediate position determined by a stop limiting the piston travel , said piston rod being movable relative to the piston between said intermediate position and a position of maximum extension out of the cylinder wherein the platform is swung up , wherein a spring , adapted to be supplied with spring force when the piston rod is moved towards its position of maximum extension out of the cylinder , urges the piston rod from said position in a direction towards the bottom position thereby to initiate at all times a lowering of the platform .