Abstract: Disclosed is an operator for a door mounted by frame means so as to be slidable along a track between open and closed positions. The door has a peripheral edge which is engaged to provide a positive locking of the door. The operator includes a shaft rotatably mounted alongside the door. A locking pawl is mounted to the shaft for rotation therewith so as to be movable between an unlocked position remote from a door edge and a locked position overlying the door edge so as to block the opening thereof. A lockout lever is also attached to the shaft for rotation therewith, and is movable between an idle position whereat the shaft is rotated to bring the locking pawl to its unlocked position and a lockout position whereat the shaft is rotated to bring the locking pawl to its locked position.

Abstract: A pneumatic powered door operator including a pneumatic differential engine with an output shaft having a slide bar applying driving action through a roller to a multiplying lever wherein the multiplying lever is pivotally mounted at one end and provided with a roller at the other end and linkage means for interconnecting the multiplying lever to a slidable door. An electropneumatic control circuit controls the operation of the engine and includes a pneumatic spring arrangement which allows manual operation of the door during electrical failure with air available while being capable of maintaining the door in a closed position when not manually actuated.

Abstract: Door operator for doors on a passenger carrying vehicle such as a bus or the like for moving a door between open and closed positions and having a locking mechanism with a lost motion action for unlocking the doors prior to the door opening cycle.