Elevator door mounting system

A system for mounting an elevator door on an elevator cab, said system comprising:

• a) a track fixedly mounted on said cab above an entrance to the cab;
• b) an elevator cab door reciprocally slidably movable on said track between entrance-open and entrance-closed positions;
• c) a plurality of guide rollers rotatably mounted on said cab door, said guide rollers being disposed in rolling contact with an upper surface of said track to guide movement of said door on said track;
• d) at least one upthrust roller rotatably mounted on said cab door, said upthrust roller being disposed in rolling contact with a lower surface of said track and biased against said lower surface and being operable to suppress tilting of said door relative to said track as said door is moved between said entrance-open and entrance-closed positions;
• and
• e) drive means mounted on said cab and engaging said door to provide motive power to move said door over said track, said drive means engaging said door at a location which does not define the center of gravity of said door.