[Corrected per Doug's comment:] When locked, the inner cylinder is prevented from rotating past the outer cylinder by little "driver pins" (blue) protruding radially through the boundary between the two cylinders. The driver pins are lined up in a row along the shared axle of the cylinders. There is some kind of spring mechanism that snaps the driver pins into place, each being brought up snug up against a "plug pin" (red). The driver- and plug-pins together make a smooth shape that exactly fits a shaft that's radial to the axle shared by the cylinders.
When each red plug pin is pushed just far enough, the point where it meets the blue driver pin will line up exactly with the "shear" boundary between the yellow inner cylinder and the green outer cylinder, at which point the blue driver pin can slide sideways past the red plug pin, and the yellow inner cylinder can rotate past the green outer cylinder. But each red plug pin must be pushed a slightly different distance in order to make it line up properly, and the cylinder will not move unless all of the plug pins are lined up at the same moment.
A key typically takes the form of a rod intended to be inserted along the shared axle of the two cylinders, one edge of which is notched up and down in a pattern that, when fully inserted, will push each spring-loaded plug pin just far enough to move it out of the way and let the inner cylinder rotate with the twisting action of the key. This rotation is connected in a variety of ways with a lever or cam that retracts a bolt out of the doorframe and back into the door lock.
If a cylinder lock is not constructed carefully, its plug pins can be pushed back one at a time until they're just at the release point. The cylinder will then turn just enough to keep that pin from slipping back, while the other pins continue to obstruct rotation. A lock picker exploits this weakness to push each pin back one at a time until all are released, using a variety of springy bent wires and a delicate sense of touch to detect when each pin has been pushed into the right position.
I tried to find information on how fast professionals can really pick locks, but it's hard to sort through the anecdotal evidence and casual bragging on the Internet. On TV, the pros from Dover can do it in just a few seconds.
Kinda fun little buggers, aren't they?
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Some high school friends and I ran our high school's audio/video club, the duties of which included distributing slide and movie projectors to teachers' rooms IAW reservations made earlier in the week, and then picking them up at the end of the day.
ReplyDeleteAs a lark, we'd also taught ourselves to pick locks. That skill came in handy in the high school, and the teachers of the time actually appreciated our skill--they didn't have to be present for the equipment delivery and pick up, and we could be more flexible about the details of those schedules. We'd routinely pick the room locks and the locks on the rooms' closet doors and teachers' file cabinets, depending on where the teachers said they'd leave the equipment in question.
We used carefully cut paper clips as our picks, and we really could run each of the locks in just a few seconds. These were not top of the line, high security locks.
Imagine students doing that in today's schools.
Eric Hines
And to think I just used my student ID card to jimmy the lock's bolt open. You were much more ambitious than I was, Eric.
ReplyDeleteOf course, my purposes were a bit more nefarious than yours.
heh
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I used credit cards in college for awhile on locks that weren't much better. But either my cards were too fragile, or I wasn't any good with them; the jimmying was too hard on them.
ReplyDeleteI went back to the picks, and I kept a perfectly innocent 6" metal ruler in my pocket for jimmying.
Eric Hines
Our student ID's were fairly sturdy, so it took a really stiff bolt to mess them up. WD-40 solved those.
ReplyDeleteheh
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"When locked, the inner cylinder is prevented from rotating past the outer cylinder by little "plug pins" (red) protruding radially through the boundary between the two cylinders."
ReplyDeleteTex, according to the diagram, I believe that's incorrect- it's the blue pins that cross the boundary between the cylinders. The red pins only cross that boundary if you put a key in that isn't correct, and is cut too high at that particular pin.
I never learned to pick locks (probably a good thing!), but rekeying locks with the kits from the hardware store, I've learned a bit about them.
Hey, you're right--in the locked position, it's the blue pins that are jamming the revolution. When the key is inserted, the red pins push the blue pins back against the springs until they're out of the way.
ReplyDeleteNot sure about building doors, but in my prime I could get the van at one of my former houses of worship open using a pocket knife in about ten seconds (early 1980s 15-passenger Ford). The sponsors were NOT amused the evening that another reprobate, ah, pardon, youth leader hotwired it after I got the doors open and we had all the choir equipment loaded and the van ready to go before the adults finished deciding that it really was time for us to leave.
ReplyDeleteLittleRed1
"Imagine students doing that in today's schools."
ReplyDeleteIndeed. I used to ride the school bus with my 12-guage and 100 rounds of ammo.
If I got in a fight with a jock or a head, it would have never occurred to me to go get Betsy out of my locker.