An ascent aid on a rail vehicle having a vehicle body includes a step and at least one folding mechanism fastened to the step at one end, as seen in longitudinal direction of the step. The folding mechanism has two lateral rods connecting the step to the vehicle body at hinges. The folding mechanism has a connecting rod additionally connecting one of the lateral rods to the vehicle body at hinges. The connecting rod is split into two parts by a folding hinge. The folding hinge is coupled to an action of force on the folding hinge causing the step to be folded at the hinges between first and second positions relative to the vehicle. In the first position, an ascent to a driver's cab of the vehicle is assisted. In the second position, the step is folded to maintain a predetermined clearance gauge of the vehicle.