What is the purpose of mechanical locking devices on a fly section ladder?

The purpose of mechanical locking devices on a fly section ladder is to prevent ladder collapse. When multiple sections of a ladder are extended, the locking mechanism ensures that each section remains securely in place, preventing any accidental retraction or collapse that could occur under weight or during operation. This is crucial for maintaining the safety of firefighters and the stability of the ladder while it is being used for rescue or firefighting operations. Without these locking devices, the risk of a ladder collapsing during use increases significantly, posing a serious hazard to personnel. The other choices do not relate directly to the primary function of these locking devices, which focuses specifically on safety and operational integrity.