Longitudinal seat adjustment system

A longitudinal seat adjustment for a seat of a motor vehicle, the seat adjustment comprising:

• two pairs (10) of rails arranged a certain distance apart from one another, wherein the two pairs (10) are comprised of a U-shaped upper rail (11) and a U-shaped lower rail (12), respectively, wherein the upper rail (11) is adapted to be connected to the seat and the lower rail (12) is adapted to be connected to a floor of the vehicle;
• wherein the upper and lower rails (11, 12) have U-shaped sections (40, 41) formed on sidepieces of the upper and lower rails (11, 12) and extending in a longitudinal direction of the upper and lower rails (11, 12);
• wherein the U-shaped section (41) of the lower rail (12) is positioned in an interior space of the lower rail (12);
• wherein the U-shaped section (40) of the upper rail (11) is positioned outside of a contour of the upper rail (11);
• wherein the two pairs (10) comprise at least one movable, plate-shaped locking part (21), respectively, wherein the at least locking part (21) is supported on the upper rail (11), respectively;
• wherein the at least one locking part (21) prevents, when in a locking position, the upper rail (11) from moving relative to the lower rail (12);
• wherein a free edge of the U-shaped section (41) of the lower rail (12) is provided with tooth-shaped slots (14);
• wherein the U-shaped section (40) of the upper rail (11) is provided on a sidepiece of the upper rail (11) and wherein the sidepiece provided with the U-shaped section (40) has slit-shaped openings (16);
• wherein the at least one locking part (21) has teeth (15) engaging the tooth-shaped slots (14) and the slit-shaped openings (16);
• an actuating element (13) connected to the at least one locking part (21);
• a spring (25) acting on the at least one locking part (21);
• wherein the actuating element (13) is adapted to move the at least one locking part (21) against a force of the spring (25) from a locking position into a release position;
• wherein the at least one locking part comprises locking plates (21) and wherein at least two of the locking plates, when the locking part is in the locking position, are simultaneously arranged in a load-absorbing path of forces passing through the U-shaped section of the upper rail (11);
• wherein edge areas (44) of the tooth-shaped slots (14) and/or edge areas (45) of the slit-like openings (16) are configured to be permanently deformable, wherein the teeth (15) of the at least one locking part (21) engaging the slit-shaped openings (16) and the tooth-shaped slots (14), when in the locking position, cause a permanent deformation of the edge areas (44) of the tooth-shaped slots (14) and/or the edge areas (45) of the slit-shaped openings (16) when a heavy load is applied such that a plastifying effect of the permanent deformation hardly changes a contact angle of the locking plates (21) relative to the edge areas (44) of the tooth-shaped slots (14) and/or the edge areas (45) of the slit-like openings (16).