What's this security mechanism called?

[deltaflex]

Hi Guys,

come across a security mechanism on a lock I picked yesterday. It has a second row of shallow holes drilled a few degrees away from the actual pin shafts. When over-lifting a pin, the plug will turn a few degrees and then get stuck. The lock needed dismanteling to be reset.

What is such a mechanism called? Any literature on this? Have you guys come across this before?

Regards from Oz!

[Evan]

What is such a mechanism called? Any literature on this? Have you guys come across this before?

Hello deltaflex, Welcome to LP101:

If the second row of holes in the plug are the same size as the pinning chambers then the cylinder would be called a "trap cylinder" and would lock solid with no non-destructive way to release it whether the lock was picked or the proper key was used...

Those holes however look like they are smaller in diameter than the pin chambers and are thus a provision for the lost ball method of construction keying...

~~ Evan

[Squelchtone]

What is such a mechanism called? Any literature on this? Have you guys come across this before?

Hello deltaflex, Welcome to LP101:

If the second row of holes in the plug are the same size as the pinning chambers then the cylinder would be called a "trap cylinder" and would lock solid with no non-destructive way to release it whether the lock was picked or the proper key was used...

Those holes however look like they are smaller in diameter than the pin chambers and are thus a provision for the lost ball method of construction keying...

~~ Evan

Evan, you probably know this, I have always wondered.. in lost ball construction keying, is the ball on the bottom of the pin stack such as in a Folger Adam cylinder, or is it in between the key pin and the driver pin? wait, mental picture just popped in my head and helped me, the ball has to be above the key pin because otherwise it would never fall from the bible into the lost ball holes.

glad we talked that one out. lol. Thanks!

Squelchtone

PS. I speculate that the construction key has deep cuts like 5 or 6 in the positions where construction balls are present, and the user key is only like a 3 or 4 cut in those positions. Can anyone verify this statement?

[femurat]

Yes it's like this, at least with mottura I had in my hands.

Cheers

[GWiens2001]

The Kwikset locks that came on my house (replaced the next day) had the construction balls, and also had drilled holes with which to remove them when the final key was used. Only had the balls under one driver pin. They were smaller than the primary holes for the pin stacks, and did not trap pins when picked. (Those locks went into my confidence pile of practice locks.)

I hear some of the KABA 8 locks use trap pins, but have yet to disassemble mine to verify.

Gordon

[Evan]

Evan, you probably know this, I have always wondered.. in lost ball construction keying, is the ball on the bottom of the pin stack such as in a Folger Adam cylinder, or is it in between the key pin and the driver pin? wait, mental picture just popped in my head and helped me, the ball has to be above the key pin because otherwise it would never fall from the bible into the lost ball holes.

glad we talked that one out. lol. Thanks!

Squelchtone

PS. I speculate that the construction key has deep cuts like 5 or 6 in the positions where construction balls are present, and the user key is only like a 3 or 4 cut in those positions. Can anyone verify this statement?

Squelch:

It depends on where in the pin stacks the ball bearings (several small sized ones) are which of the permanent keys will act as the CBOK (Construction Break-Out Key) voiding the construction masters... It can be either the master key or the change key based on where they are placed in the pin stack...

The large single ball bearings used at the bottom of pin stacks which contact the key are used currently in severe use applications like the Folger Adams mogul cylinders and some chambers (usually the first two or three near the cylinder face) of Corbin-Russwin master ring cylinders and are only used because they are made of a harder material than the pins and prevent premature failure of the lock due to the pins wearing out... Such ball bearings were formerly used in high traffic/use locks before harder metal alloys were available as ball bearings were pretty much the strongest metal available in such a small size at the time... When such ball bearings are used in all chambers of a cylinder it leaves the lock vulnerable to "combing"...

As far as the bitting depths of construction master keys, they typically are the deepest possible cuts (and even sometimes outside the normal bitting range being deeper than normal keys would ever be) and usually have a strict relationship between their depth and the depth of the permanent system keys and the chamber of the lock dedicated to the construction keying function is normally not able to be used in key system bitting progression...

~~ Evan

[MacGyver101]

Not much to add beyond what Evan said... but the Kwikset Rekeying Manual does have a diagram of their "Protecto balls" in Figure F on Page 7, which gives you a visualization of how the pin stacks are laid out.

In their system, a cluster of three small ball bearings take the place of a #2 master wafer -- so the construction key would be two cuts deeper than the homeowner's key for the pinstack(s) that contain the ball bearings.

[MacGyver101]

Sorry for the double-post: for the original poster's question about deadlocking cylinders and trap pins, there's a good YouTube video on Royal Guardian locks that shows how their deadlocking mechanism works.

There are several cylinders on the market that use a principle similar to that; Mila's Evolution cylinder is the only one I happen to own, but I know there are a half-dozen other similar ones that are available. They all share a common goal of trying to lock the cylinder if it's turned without something in the keyway to hold the bottom pins at the correct height.

[deltaflex]

Thanks guys! Very helpful. It's mind-boggling how much in depth knowledge you guys have! Glad to be part this community!

[minifhncc]

the cylinder would be called a "trap cylinder" and would lock solid with no non-destructive way to release it whether the lock was picked or the proper key was used...

What would be the use/purpose of that? Where is a "trap cylinder" commonly used in?

[GWiens2001]

The benefit in trap cylinders is that you find out if someone is attempting to bypass your security. This is for places where it is more important to know if someone is comprimising your facilities than it is convenient to have an easy way to reuse the lock.

This kind of lock typically requires destructive entry when tripped. At least if it is mounted in use. We don't advocate picking locks in use, so for some of these locks, if it is not mounted, there may be non-destructive methods of opening, or at least a way that will allow the lock to still be used. Don't think I am allowed to say more.

Gordon

[MacGyver101]

What would be the use/purpose of that? Where is a "trap cylinder" commonly used in?

It's offered as an additional security mechanism in some cylinders; the idea is that if the cylinder is picked, bumped or opened in any other way -- other than with the correct key -- the trap pins will fire and lock the cylinder in place, preventing someone from turning the cylinder further to unlock it. Ideally, it prevent someone from breaking in, and also signals to the owner that the lock had been tampered with.

It's a bit of an extreme approach, though, as it locks everyone out (even if you have the correct key); in some cases, you might need to destroy the lock in order to open the door once the trap pins have fired.

[Evan]

the cylinder would be called a "trap cylinder" and would lock solid with no non-destructive way to release it whether the lock was picked or the proper key was used...

What would be the use/purpose of that? Where is a "trap cylinder" commonly used in?

@minifhncc:

There are two types of "trap cylinders" that I am aware of,

The kind everyone is discussing here where if you pick the lock or bump it and you do not have the proper key with the proper bitting depth under the trap pin it will secure the lock sometimes requiring destructive methods to remove depending on how it was tampered with... This kind of trap cylinder is a security device meant to protect the lock from tampering...

Then there are trap cylinders which are keyed in a way to trap a specific key if it is used in the lock... This is useful in facilities with a good key control program in place to "collect" keys which were not returned as they should have been... To use such a trap cylinder effectively you need to anticipate where the unauthorized key holder will attempt access in order to figure out which door to install it in... The end result is often finding the key left in the lock or finding the bow snapped off the unauthorized key which was trapped by the lock with no way to find out who it was supposed to be issued to unless the facility also engraves key serial numbers along the bottom of the key blade... (This is a service that lock manufacturers should start doing with high security/restricted keyway products, rather than relying on hand or machine stamped serial numbers being added later on by the customer)

~~ Evan

[minifhncc]

That's interesting.

But, how does the lock know to trap a certain key? Also, how does it knows if the lock has been picked or if a key has been used?

[GWiens2001]

It knows if the lock has been picked or bumped because when the plug is turned, a spring and trap pin push down on the key pin(s). If the key is used, it holds the key pins in place, preventing the trap pin from dropping into the pin stack holes in the same way that the key pins keep the driver pins from dropping. The trap spring is usually much stronger than the driver pin springs, too. If the key is not used, the trap pin can be thrust into the key pin holes, locking the plug in place.

By the way, the are very good questions!

Gordon