Patent ID: 7464794

Claim:
Coupling device for an elevator car door and an elevator landing door comprising: cams integral with the car door and driving the landing door, said cams being movably mounted with a variable distance from each other on the car door, independently from a car door drive belt; and a connecting drive rod to separate the cams with a variable distance, wherein the connecting drive rod is mounted on the car door, wherein the connecting drive rod is connected to the car door drive belt and to one of the cams, wherein said connecting drive rod is configured to exert a lever action on said one of the cams to drive said one of the cams towards and away from another of the cams with a large displacement relative to a small overtravel drive of the car door drive belt, in order to: (a) unlock a coupling plate and a landing door drive coupling when the doors open; and (b) lock the coupling plate and the landing door drive coupling when the doors close, wherein said connecting drive rod is: (a) hinged at a first point on a trolley panel of the car door; (b) hinged at a second point on an attachment tab to the car door drive belt; and (c) hinged at a third point on said driven cam, wherein a dimension Δ is a distance from the first point at which the connecting drive rod is hinged to the trolley panel to the second point at which the connecting drive rod is hinged to the car door drive belt, wherein a dimension π is a distance from the first point at which the connecting drive rod is hinged to the trolley panel to the third point at which the connecting drive rod is hinged to the driven cam, and wherein a ratio of Δ to π is less than 1.