Abstract: An apparatus for opening and closing a car door and a shaft door of an elevator installation includes an entraining system (E) arranged at the car door and a cooperating locking mechanism (L). The entraining system (E) has a pair of spreadable entraining cams (1, 2) connected to first and second levers (3.1, 3.2) forming a parallelogram. A stationary guide rail (4.1) on the car has an entry cam (4) which receives a roller (5) on the entraining cam (1) to spread the parallelogram against a tension spring (6) and into engagement with first and second shaft lock rollers (7a, 7b) on the floor door to couple the doors together. The locking mechanism (L) has a transmission lever (8) attached to one entraining cam (2) and pivotally connected to a locking rocker (9) carrying a support roller (10). The locking rocker (9) also is pivotally connected with a catch (11) having a lug (11.2) that detents with a stationary lock plate (13) on the car to prevent opening of the car door.