Access systems for a passenger compartment

A system to access a passenger compartment by a doorway made in a chassis frame of the passenger compartment, said access system being constituted by at least one door hinged with respect to said chassis frame by a first horizontal articulated joint and forming an inclined ramp in its open position, wherein said system comprises at least one actuator to move said door, linked to said door and said chassis frame, a step plate at least partially covering the outside of said door and hinged with respect to said chassis frame by a second articulated joint parallel to said first articulated joint and with a hinge pin that is offset with respect to the first articulated joint, said step plate being linked to said door by at least one drive element that is connected to said door by a third articulated joint and to said step plate by a fourth articulated joint, the pins of said first, second, third and fourth articulated joints being parallel to one another and arranged so as to form the four summits of a parallelogram deformable between an open position and a closed position of said door.