Abstract: Embodiments are directed toward a pulley. The pulley preferably has a fixed side plate, an operable side plate, a sheave, and a double-action lock. The operable side plate is preferably transitionable between a closed configuration and an open configuration. The sheave is preferably disposed between the fixed side plate and the operable side plate. The double-action lock is preferably transitionable from a locked configuration to an unlocked configuration upon completion of two separate and distinct actions. The lock in the locked configuration preferably prevents transition of the operable side plate from the closed configuration to the open configuration. The lock in the unlocked configuration preferably permits transition of the operable side plate from the closed configuration to the open configuration.