Which device prevents operation if the seat is not locked?

• A. Cutoff Switch
• B. Emergency Stop Button
• C. Interlock Sensor
• D. Seat Belt Reminder

Answer: (A)

The key idea here is safety interlock logic: the machine won’t start or continue to operate unless the required safety condition is met. For ensuring the escalator or moving walk is only run when the seat is properly locked, the sensor that checks that condition is an interlock sensor. It monitors whether the seat lock is engaged and gates the control circuit so operation is prevented if the seat isn’t locked.

Other devices play different roles. A cutoff switch is a general shutdown device that can stop machinery when a safety guard or related interlock is released, but it isn’t specifically tied to verifying that the seat is locked. An emergency stop button is used to halt the machine quickly in an urgent situation, not to enforce seating readiness. A seat belt reminder simply prompts the user to buckle up and does not prevent operation.