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HI-SHEAR MILITARY PADLOCK Application: Government/Military
This massive body measures 4'' across, 3'' tall, and nearly 2'' thick.
Weighing 4 lbs. 11 ounces, it's comprised of a blast/explosion-proof alloy.
The contol key for this lock uses the exact same bitting as the operating key. So, to create a contol key,
simply file a "notch" near the bow in the appropriate place, thus allowing it to turn the plug counter-clockwise.
Inside this tank of a body is a classic Medeco core. My knowledge of Medeco is far from extensive, so I won't get real technical here. I will, however, try to give you (
in laymans terms) a brief, general idea of how it operates and some of the security features it possesses.
One of several things that makes Medeco high-security is the use of a sidebar that interfaces with a groove that's been milled into the side of each keypin. The sidebar is spring-loaded and protrudes from the plug. This, obviously, prevents the plug from turning even if the pins have been set to the sheer-line. What this means is that the pins not only have to be set vertically... they must also be set rotationally in order to activate the sidebar.
The groove on each of the six keypins must align with each of the six 'teeth' on the sidebar. When this occurs, the sidebar is allowed to be retracted far enough to become flush with the outside of the plug, thus allowing it to be turned. Torque (
from turning the key) provides the pressure to push the sidebar in.
To further complicate rotational manipulation, some keypins have a shallow groove in addition to the 'true' groove.
I don't know the technical term for these, but I call them 'false gates'.
So, if you take a look at some of these pictures, I'm hoping you can get a pretty good idea of how this mechanism works:
the
chisel point tips of the keypins along with the
angled cuts on the key... the
sidebar teeth along with the
grooves in the keypins.
The design, really, is something to be appreciated. It's quite beautiful, and gets me rather excited. I think it'd be safe to say that it was truly revolutionary at the time Medeco (Mechanical Development Company) first introduced it. In fact, for some time, these locks were widely considered to be "un-pickable".
To prevent drilling attacks (
or at least slow the process), 4 hardened steel pins are stratigically placed near the face of the plug. Three of them, at 12:00, shield the keypins. A fourth, at 3:00, protects the sidebar. Also protecting the sidebar is a hardened ball-bearing embedded in the front end of the sidebar itself.
Other facets of security (
I won't go into): KEY CONTROL: restricting who can produce/duplicate/distribute keys,
and who is authorized to purchase keys. And, KEYWAYS: I'm told there are literally hundreds of variations.
Drivers: 5-standard, 1-lipped mushroom.....
Keypins: 3 of the 6 have false gates. 4 of the 6 are ARX (
Attack Resistance X-tended)
*
Caught on Camera*
http://www.youtube.com/watch?v=zyefjlYU9xk