Lever tumbler lock is a type of mechanical fastening device, distinct for its use of levers to prevent the bolt from moving in the lock. Comprising a set of levers (or tumblers), a bolt, and a key specifically cut to correspond to the arrangement of the levers, it provides security by requiring the correct alignment of these levers for the bolt to be moved. Each lever must reach a specific height to allow the bolt to pass, and this height is determined by the key’s profile. Commonly found in safes and older door locks, this lock type offers straightforward mechanical reliability and is less susceptible to picking than pin tumbler locks due to its unique configuration.
The design of lever tumbler locks allows for varying levels of security by adjusting the number and complexity of levers used. A greater number of levers increases the permutations of key profiles needed to unlock, thereby enhancing security. Unlike more modern cylinder locks, lever tumbler locks do not use springs, which minimises risk of lock failure due to broken springs. This durability, combined with the simplicity of its mechanism, makes it a preferred choice for high-use, low-maintenance environments.