Question 28 1AE01 - First Assistant Engineer

The Correct Answer is D **Explanation of Correct Option (D):** Door interlocks (specifically, door locks and safety circuits) are fundamental safety features in all passenger elevators, including those found on ships utilizing winding drum or traction drives. Their primary purpose is to ensure the safety of passengers by controlling the operational status of the elevator car based on the physical state of the hoistway and car doors. The system is designed to prevent the elevator from moving (hoisting or lowering) unless all doors—both the landing doors and the car door—are securely closed and electrically proven to be locked and latched. Therefore, the interlocks prevent operation if the doors are open and permit operation only if they are proved closed. **Explanation of Incorrect Options:** * **A) Door interlocks are used to prevent elevator operation if the doors are still closed and only allow elevator operation if the doors are proved open.** This statement is the exact opposite of the interlock's intended function. Allowing the elevator car to move while the doors are open would be extremely dangerous and violate safety standards. * **B) Door interlocks are used to prevent elevator operation in a shipboard emergency when elevators are not to be used.** While elevators might be taken out of service during certain shipboard emergencies (e.g., fire), the door interlocks themselves are not the primary mechanism for this shutdown. Other emergency controls (like a fire recall system or main power disconnects) are responsible for taking the car out of service. The interlocks' function remains strictly tied to door closure during normal and operational use. * **C) Door interlocks are used to over-ride elevator emergency status in a shipboard emergency when elevators are required to be used.** This is incorrect. Interlocks are safety devices that complete the safety circuit; they do not typically act as an overriding mechanism for emergency status. Furthermore, safety procedures usually emphasize stopping or controlling elevator use, not overriding safety features, during emergencies.