Retractable running-board, especially for a railway car door

A retractable running-board especially for the door of a railroad car, and comprising a substantially rectangular movable step connected to the car floor by means of an articulated quadrilateral linkage comprising two pairs of link-arms connecting said floor to two transverse arms forming part of said movable step, said quadrilateral linkage being deformable in such a manner that, in respective positions of service position and withdrawal position, it becomes respectively concave and convex, so as to provide an abutting force in service position resulting from its concave form, springs for locking said service position by maintaining said abutting force, said springs (15A, 15B) being connected by one end to the movable step and by the other end to a lever (16A, 16B) that swings about an axis coaxial with the connection points of the rear link-arms (8A, 8B) with said floor of the car, said levers being pivotally connected to said rear link-arms.