NATO Mersey

= NATO Mersey =

The Mersey is a lever lock made by the North Atlantic Treaty Organisation (NATO) Ministry of Defense (MOD). It features a distinct puck shaped housing which is designed to fit on safes used by the MOD. The Mersey can also be identified by its V shaped key which actuates two independent sets of levers inside the lock.

General
The NATO Mersey exists in two distinct guises, each with some evolutionary revisions: the 10 lever variant and the 14 lever variant. Both locks share a number of common security features having a common ancestry. Made for the North Atlantic Treaty Organisation (NATO) during the 1970’s through to the 1990’s, these locks use a unique V-shaped key.

In some instances, the keys for the Mersey were stored in a key safe protected by a Mark IV Manifoil combination lock.

Key security features
The principle security features are common to both the 14 and the 10 lever. They are:
 * Two stacks of levers that are operated in parallel. Both of these must be set before the stump will pass the true gates
 * The majority of levers have at least 1, if not 2, false gates.
 * The stump and the false gates are made in such a way as to lock firmly together
 * The bolt locking mechanism.

It is the last of these that is reasonably unique to the NATO Mersey locks

The 10 lever variant
The 10 lever variant of the Mersey exists in at least three iterations. There are those early models where the lever pivot bolt is free to slide along a captive slot, in later models this slot becomes a round hole and finally square. The ability of the lever pivot is a key part of the bolt blocking mechanism.