摘要 |
<p>A door operator (11) for a reversibly operable door (12) includes a frame (14) and a carriage (24) movably mounted on the frame (14) and attached to a door (12) for moving the door (12) between open and closed positions. A drive member, specifically a roller chain (21), extends along the frame (14) and moves the carriage (24). A drive train is provided within a housing (32) and is connected for moving the drive member, and a control circuit (36) is provided for controlling the drive train to open and close the door (12). A pair of limit switches (61,62) is mounted within the housing (32) and connected to the control circuit (36) for stopping the drive train when the door (12) has reached a completed position. A pair of limit cams (50,51) are adjustably mounted on a limit wheel (47) within the housing (32) and separate from the carriage (24) for engaging the limit switches. The limit wheel (47), which is separate from the drive member (21), is connected to the drive train to rotate when the drive train moves the carriage (24). The placement of limit switches and associated connecting wiring along the frame (32) in the garage ceiling is eliminated. The limit cams (50,51) can be easily and automatically positioned on the limit wheel (47) by pushing a single switch without any manual movement of the limit switches or of the movable cams that contact the limit switches. <IMAGE></p> |