It is a Master padlock, product number 500D. I found a link on master's website which details the lock I have: http://www.masterlock.com/cgi-bin/prod_ ... umber=500D
Here is a picture I drew of the lock: http://www.teamd5r.netfirms.com/masterlock.htm
Some interesting things I noticed about this lock. First off the key design is very strange. It looks like the key is NOT your usual protrusion with points that stick up and push up pins, but rather more like a stick with rectangular cut-outs in just the right places to avoid discs placed in the lock.
The keyway itself looks like it contains 4 discs of varying thicknesses, which line up with the four "cutouts" in the key (see picture). The discs are elonguated so the key can slide in, but when it turns, any key of the wrong size/shape will hit the discs, and prevent rotation. Something interesting I noticed about the keyway is there IS NO LOCKED/UNLOCKED POSITION. Weird. The keyway's rotation is springloaded, and the key just rotates around and around in either direction. At the 90 degree point the shackle unlocks, and the key can continue to rotate in the same direction. 90 degrees later the key can be removed. The lock's keyway never needs to be rotated back.
My guess is it's a "disc lock", but I can't find the document that talked about them in the FAQ anymore. I saw it once, but now I can't find it
. Master Lock calls it their "patented locking lever", implying it's something you wouldn't find on other locks. It isn't in the MIT guide, or the "lockpicking courses" link that was provided just below the MIT guide's link. I think there might have been mention of it in the keyblanking, but it didn't looks or sound quite right.
Another thing I noticed is the notch in the padlock's shackle is on the wrong side, It is on the pivoting side of the shackle, opposite to what you would normally expect, and the actual cutout is not on the side of the shackle, but on the front. This, I would guess, is to mislead mr.smith with his trusty padlock shim. You would be trying to shim the wrong side of the lock, and if you did try to shim the other side you would be off 90 degrees in your attempt to push the fence out of the way.
I've never seen a lock like this before...
I guess I'm asking how I should go about trying to pick/comprimise this lock, outside of shimming it, but more so I'm just bringing up something which i think might be fun to discuss
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