Mechanical locks are the backbone of your security system. There are three types of tumbler locks: pin-tumbler, disk-tumbler, and lever-tumbler. Pin-tumbler locks are the most common. The tumblers in this type of lock are small pins. The modern door lock is a compact pin-tumbler cylinder lock of the type developed (186 by the American inventor Linus Yale. Most high-security locks have pin tumblers. Disk-tumbler locks are often used in desks and file cabinets.