Which extension ladder components are mechanical locking devices that are used to secure the extended fly sections?

The correct choice involves the pawls, which are mechanical locking devices integral to the operation of extension ladders. Pawls engage with notches or teeth along the fly sections of the ladder, ensuring that once the ladder is extended, it remains securely in position. This mechanism is crucial for the safety and stability of the ladder in use, preventing sections from inadvertently sliding down, which could jeopardize the safety of the firefighter.

In the context of extension ladders, staypoles refer to the support devices that stabilize the ladder but are not locking mechanisms for the fly sections. Stops serve as physical barriers that prevent the sections from over-extending but do not lock them into place. Halyards are related to the ropes or cables that assist in raising and lowering the ladder sections but do not function as locking devices. Thus, pawls play a pivotal role in the ladder’s safety features, making them the correct choice for this question.