Tumbler combination lock with serrated key - has base tumbler spring loaded in opposite direction to others, for operation only when key is fully inserted

摘要

The lock has a rotor (1) spinning inside a fixed barrel. Surrounding the rotor are tumblers (4), all spring loaded in the direction (F'). The base tumbler (7) is spring loaded in the opposite direction to the others (F). A key (3) is inserted into the hole (2) in the centre of the rotor and notches in the key (6) slip into grooves (5) in the tumblers turning the lock only when the key is pressed home, so that the inclined face of the key end (9) releases the end tumbler by engaging in a groove (8).