any 2 of 3 keys needed to open lock - does this exist?

[Mr. Keys]

simple:
three descrete locks on the door.

a lever mechanism that when 2 locks are unlocked it unbolts the door.

balance the lever system well and they have to be opened nearly simultaneously.

I am having trouble picturing this. Can you draw a diagram?

now the problem with that system is that there's functionally a prescribed known time lock on teh system, that can be compromised by compromising any 1 guard.

eh, that's no good.

to me a stronger system would be an owner key (since they could need to access any time) each discrete, and a guard key (uniform across) that open 2 locks to throw the bolt.

Right. I modified my solution to optionally allow for a master key. I've got to finish that article...will have to wait until after the holidays.

What would you call this type of system? I am thinking the name "Majority Interlock"

[Kiknads]

could you set something up with a long bolt where unlocking 1 lock would pull the bolt 1/2 way out of the hole and unlocking a second would take it completely out of the lock. so 3 seperate carriage attached.

[2octops]

Lemme see if I have this right.

You want a locked door that requires 2 of 3 independent keys to open the door.

That's been around for a very long time.

It's not a complicated thing to do if you use boltwork like inside a safe/vault door and 3 seperate locks on floating bases.

I'll dig thru some books and see if I can find a pic.

[hurri]

hmmm..sounds interesting...

[greyman]

I haven't heard of a mechanism that requires any 2 of 3 possible keys (simultaneously) to operate. It's not a safe deposit that I know of, although there are types that require three keys, or two keys and a combo, but all of these are required together, not a subset of them.
There's also sequential lever locks where one key draws the bolt a bit, the second a bit more, the third the rest of the way.

I think I have a solution to the 2-out-of-3 lock that uses six keyways. I'll try to draw a picture later and post it.

Can I ask the original poster what is the application for this idea?

[greyman]

This is the idea I had for a 2-out-of-3 "majority interlock". The 6 cylinders are in 3 pairs. Because of the gears, each lock in a pair must be operated together. Any pair (operated by either keys 1+2, 1+3 or 2+3) can operate the lock.

Sorry - I think the picture is a bit too big.

cheers

greyman

[raimundo]

you should look at some old safe and vault tech books, there were time locks that locked out until the set time, and these had redundant clocks in which a failed clock could not by itself cause a lockout if the other clocks agreed that it was time to open, these were mechanical clocks, there were systems with three and some were four clocks, I don't know the mechanics, but the clocks were mechanical and whatever the system was that allowed for a majority of the clocks to allow an opening would also have been mechanical, I see no reason why such a system could not have the clocks replaced with locks. its just a matter of how the mechanics were arrainged.

[Nasydave]

If you're looking for the poor man's way of doing something like this, picture this: (sorry, no good at graphics, but I'll describe it)

three deadbolts mounted in a "tube" that holds them all pointed the same direction, but able to slide closer to each other *IF* the deadbolt is unlocked. The left one is up against the end of the "tube". The next one is up against the extended bolt of DB#1. The third DB is up against the extended DB of #2. At the right of the third deadbolt is a real bolt, with a plate which keeps it from turning/misaligning in the "tube" The real deadbolt must be drawn in by at least the length of two of the previous deadbolts before clearing the frame.

As you unlock one of the DBs, the next one slides over by the length of one bolt. The real deadbolt is still going across the lockframe by one bolt length. Only when you unlock a 2nd deadbolt and slide another over does the real bolt clear the frame.

It wouldn't matter which keys you had, as long as you had two.

By the way, are you building a launch device for nuclear missiles?
------ -------
PPP[[]] Locked position
------ -------
^
------- --------
IIP[[]] Unlocked (with 1st two keys)
------- --------
^
------- -------
IPI[[]] Unlocked with 1st and 3rd key
------- -------
^

P= locked deadbolt with bolt sticking out
I = unlocked deadbolt with bolt withdrawn
[[]] = "real deadbolt"
^ = door frame

I know, lousy drawing, but might be enough for you to get the idea.

[Trip Doctor]

I think Unjust and Kicknads had a similar type of idea, and probably the most applicable here (IMO) in making a mechanical type of lock like you described.


You said you didn't want anything electronic, but perhaps you could have something like mechanical locks (pin tumblers or w.e), operating digital logic switches (not sure if you're familiar with those). This would make the system real simple.

A problem with this is that it definetly COULD be compromised without dealing with the mechanical part, but if made right, the only way someone would be able to manipulate through it is if he knew the exact inside layout of the lock, managed to drill/cut open the exact locations, and was able to get to the circuit to the point where he would be able to differentiate between the electronic parts.. oh, and he would have to be familiar enough with electronics to be able to tell what part does what, the layouts of the chip/chips used, and differentiate between real and fake connections present in the circuit (assuming some fake ones were built in there). So, if made right, it would be pretty infeasible to manipulate the electronic part of this lock (even though there is no coding in the system). (The 'theif' would have more success clubbing the guards on the head and taking their keys, or just picking the mechanical locks - which I assume would be very secure to start with as well.)

Considering that this would be a custom lock for your business/place/secret missile silo :P, if someone was able to get that much detailed information on the lock (not too mention had some skills in both mechanics and electronics), you probably have another problem you gotta worry about.


Hmm, that was a lot more typing than I expected. :P

[Nasydave]

Here's what I think would be the easiest solution, but it makes the following assumptions:

A. your key security is good
B. Nobody would duplicate the keys

(I'm using a door as an example, but it could be anything lockable with the right locks)

All you really need is two deadbolts on the door. locks (a and b)

Lock A is keyed to key A and has a master key C
Lock B is Keyed to key B and master key C

So keys A and C can open both locks
Keys B and C can open both locks
Keys A and C can open both locks.

Now, A can't do anything by himself. B can't do anything by himself.

If C makes a duplicate key, he can open it by himself. That's the one hole I see. I suppose if you are the one handing out keys, give this one to the person most trusted.

[SemiShady]

here is my attempt. very simple. (the 2-key locks are to be designed however they currently are in real life [gears connecting them or whatever])
duplicate keys don't mater, you need 2 different ones



obviously lots of little things i didn't draw would be implimented to prevent tampering, wanted to keep it simple.