linux4all
Hi-Shear LK-1200
This lock was only made from 1982 to 1983 (as far as i am aware) to be used in high security applications in various branches of the US military (namely weapons creates and "to safegard nuclear weapons". This was a special project, as Hi-Shear does not generally produce locks; they are a company that produces airspace tools and fasteners, including exploding rivets for jet cockpits. The lock has a removable 6 pin Medeco cylinder, and came standard with 3 keys, 2 standard and one control, that allowed to actually pull out the cylinder.
The gap in the shackle is designed to very snugly fit the staple of various crates and i would think gates, especially those securing nuclear weapons, which was where this lock saw most of it's use, according to documentation.
The lock is made of some sort of cast steel, the shackle is hardened steel with a carbide insert to protect it from being cut apart, its very thick and heavy, looks like it will easily survive a few rounds even from moderate caliber weapon. The keyway is protected from drilling by a ceramic plate.
The only problem with the lock was that because of it's weight, over a year's use, it would actually sag down the lid, which forces the 2 part staple to spread apart enough to jam the shackle such that even with a stock key, the lock would be nearly impossible to open. Add to that some rust, salt and dust that gets built up when the crates get transported, left outside, or shipped, and its a recipe to an unlocking disaster. The next generation locks, such as Sargent and Greenleaf 833, are actually lighter, and with a different weight distribution, as well as an improved locking/unlocking mechanism, which solved the problem. (You can see in the pictures that show the bottom part of the lock, that in order to unlock the 1200 after it had jammed, they had to loosen the shackle by hitting it with a hammer from underneath)
This particular lock is restored, the cylinder was rusted and inoperable, it was replaced with another government keyway medeco cylinder, the only problem was getting the control key to work, as the notch that was present on the original keys that allowed it to be turned counter clockwise to unlock the pins that hold the cylinder in was not present on the control key, but a little bit of grinding later all works well...
(P.S. if anyone has any more info on this lock, i would very much like to learn more about it)
P.P.S. a friend of mine is writing up a paper (long paper) on locks, this one is going to be one of them, so while the picture is creative commons, share alike, attribution non-commercial, the information (though vague) is copyrighted until he finishes the report, I'll post a link when the report is made public, sorry for the inconvenience.
Hi-Shear LK-1200
This lock was only made from 1982 to 1983 (as far as i am aware) to be used in high security applications in various branches of the US military (namely weapons creates and "to safegard nuclear weapons". This was a special project, as Hi-Shear does not generally produce locks; they are a company that produces airspace tools and fasteners, including exploding rivets for jet cockpits. The lock has a removable 6 pin Medeco cylinder, and came standard with 3 keys, 2 standard and one control, that allowed to actually pull out the cylinder.
The gap in the shackle is designed to very snugly fit the staple of various crates and i would think gates, especially those securing nuclear weapons, which was where this lock saw most of it's use, according to documentation.
The lock is made of some sort of cast steel, the shackle is hardened steel with a carbide insert to protect it from being cut apart, its very thick and heavy, looks like it will easily survive a few rounds even from moderate caliber weapon. The keyway is protected from drilling by a ceramic plate.
The only problem with the lock was that because of it's weight, over a year's use, it would actually sag down the lid, which forces the 2 part staple to spread apart enough to jam the shackle such that even with a stock key, the lock would be nearly impossible to open. Add to that some rust, salt and dust that gets built up when the crates get transported, left outside, or shipped, and its a recipe to an unlocking disaster. The next generation locks, such as Sargent and Greenleaf 833, are actually lighter, and with a different weight distribution, as well as an improved locking/unlocking mechanism, which solved the problem. (You can see in the pictures that show the bottom part of the lock, that in order to unlock the 1200 after it had jammed, they had to loosen the shackle by hitting it with a hammer from underneath)
This particular lock is restored, the cylinder was rusted and inoperable, it was replaced with another government keyway medeco cylinder, the only problem was getting the control key to work, as the notch that was present on the original keys that allowed it to be turned counter clockwise to unlock the pins that hold the cylinder in was not present on the control key, but a little bit of grinding later all works well...
(P.S. if anyone has any more info on this lock, i would very much like to learn more about it)
P.P.S. a friend of mine is writing up a paper (long paper) on locks, this one is going to be one of them, so while the picture is creative commons, share alike, attribution non-commercial, the information (though vague) is copyrighted until he finishes the report, I'll post a link when the report is made public, sorry for the inconvenience.