The basic principle.

A door operator drives the car doors through a mechanism such as belts, linkages or other transmissions. The operator’s motor control shapes opening and closing speed and force.

On many automatic lifts, coupling at the landing allows the car-door mechanism to move the landing doors too. Details differ, and some installations use other arrangements.

A close command meets an obstruction.

A worked-through example

The system may detect an obstruction and reopen according to its design. The door operator, detection devices and controller each contribute to that response.

Follow the relationship.

  1. CommandRequests opening or closing.
  2. OperatorConverts motor movement into panel travel.
  3. FeedbackReports movement or completion conditions.
Conceptual relationships; arrangements vary by installation.

Connect it to the lift.

Door motion quality depends on tracks, rollers, linkages, panels and control as well as the motor. A light curtain detects in its intended area; it is not evidence that the door is mechanically locked.

A closer look

Door travel profiles may reduce speed near the end of travel. Mechanical resistance and feedback errors can disturb those profiles even if the motor itself is healthy.

Check your understanding

Does a door motor stopping prove that all landing doors are locked?

Reveal the explanation

No. Motion and locking are separate conditions with distinct monitoring.

Further reading.

Otis: the basic workings of a lift