US Patent 9222283 Combination lock with override key

A combination lock, such as a dial combination cam lock, has a mechanical key override, the mechanical key extending through the manual knob of the cam lock. For a lost mechanical key situation, or to change the mechanical key, a special key or device can be inserted to enable the knob and key core or plug to be rotated to a further position not normally available. In this position the key, knob and core can be removed, then replaced with a different key and core, preferably using the same knob.