The basic principle.

A landing-door lock combines a mechanical locking function with associated monitoring. The purpose is not merely to notice a panel near its closed position but to establish the intended locked condition.

An interlock relates permitted actions to other conditions. Normal travel depends on the required door conditions being established, alongside other system permissions.

A panel reaches its end position.

A worked-through example

The door may appear closed while the locking mechanism has not completed its movement. A door-position indication alone does not prove the lock’s condition.

Follow the relationship.

  1. Door closesThe panel reaches the required position.
  2. Lock engagesMechanical restraint is established.
  3. Condition is monitoredThe control system receives the intended confirmation.
Conceptual relationships; arrangements vary by installation.

Connect it to the lift.

Car-door and landing-door provisions differ across designs. Fault investigation must preserve their protective function; bridging contacts or forcing locks is not a legitimate operating workaround. The lesson explains the relationship rather than an access or bypass procedure.

A closer look

Some lift movements have specifically engineered door-zone or re-levelling provisions. Those do not justify assuming that movement with an unproven door condition is generally permitted.

Check your understanding

Is “door closed” always equivalent to “door locked”?

Reveal the explanation

No. Closing, mechanical engagement and monitoring are related but distinct.

Further reading.

Optional reading to explore this lesson in more detail.