Associated Locksmiths of America (ALOA) Practice Test

The lever tumbler lock is best known for its side bar mechanism, which adds an additional layer of security beyond traditional pin and tumbler systems. In a lever tumbler lock, the levers must be lifted to a specific height in order to allow the sidebar to move freely and permit the lock to open. The sidebar interacts with the levers, preventing the lock from turning unless the correct key is used. This mechanism makes lever tumbler locks particularly secure, as their design is more complex and less susceptible to common lock-picking methods.

While the other types of locks mentioned have their own mechanisms—pin tumbler locks use a series of pins that must align at the shear line, disc tumbler locks involve rotating discs that must be aligned, and warded locks utilize a barrier to prevent specific key shapes from entering—they do not incorporate a sidebar mechanism, which is distinct to lever tumbler locks.