Clarification on EVVA 3KS functioning..

[absynthe]

I have been looking at the available pictures of cutaways of the EVVA 3KS lock and think I understand how it works. Here is a link to a drawing:

http://s175.photobucket.com/albums/w132 ... VVA3KS.jpg

If you click on the picture it will become larger and the text won't be messed up. So when the key is not in the lock, the 12 sliders rest on the bottom because of gravity. The two sidebars are not able to go into their recess and stop the cylinder from rotating (this is the left side of the picture). When you insert the key, the sliders are pushed up and the control pins are aligned. The side bar is then able to move into its recess and the cylinder can move. There are also some bars at the top and bottom? They fit into grooves on the key and won't allow it to turn if they don't match? (I read that this can easily be bypassed)

If this is correct so far, I have three questions:

1) Since the sliders are held up by the grooves in the key and otherwise fall back due to gravity, what is the force that makes the sidebar want to move into the recess? Does the turning action of the cylinder try to push the bars into their recesses? I see that there are what appear to be springs in the diagrams. It would only make sense if they were on the external side to push the sidebar in (doesn't look like that on the diagram) or on the inside part of the sidebar and are actually pulling the sidebar in. I am confused.

2) Since the sidebar must be feeling some force that makes it want to go into the recess, isn't there some sort of sensory feedback on at least one of the sliders when it is pushed into position? Maybe it has high tolerances and doesn't bite enough to actually hold the slider in position when picking?

3) According to LSS, the grooves on the top and bottom of the key can be bypassed. What is the purpose of these grooves and how do they work? The bypass method is LSS seems so silly that it doesn't seem to have a security function.

Anyway.. I think this is an interesting lock (it at least has an interesting key) Here are my sources:

1) Locks, Safes and Security
2)http://locksandsecurity.blogspot.com/2007/06/evva-3ks-cutaway-success.html
3)http://www.toool.nl/cutaway1.pdf

[absynthe]

Sorry... one more question..

4) What are the purpose of the sliders with two control pins? Is this for master keying schemes?

[bluestar]

They fit into grooves on the key and won't allow it to turn if they don't match?

That's some kind of profile, not really important for security. See answer 3 below.

1) Does the turning action of the cylinder try to push the bars into their recesses?

yup.

2) Since the sidebar must be feeling some force that makes it want to go into the recess, isn't there some sort of sensory feedback on at least one of the sliders when it is pushed into position? Maybe it has high tolerances and doesn't bite enough to actually hold the slider in position when picking?

Yes, but there are 12 sliders, they have false notches, the control pins where you could feel something are very small, and they are har to reach. Put in high tolerances and you have a hell to pick.

3) According to LSS, the grooves on the top and bottom of the key can be bypassed. What is the purpose of these grooves and how do they work? The bypass method is LSS seems so silly that it doesn't seem to have a security function.

yup. This is similar to passive pins in pin tumbler locks.

What are the purpose of the sliders with two control pins? Is this for master keying schemes?

No, they're for the double curve on the key. The sliders with one control pin are moved by the single curve on the key (the deeper one) and the sliders with two control pins are moved by the double curve.

Hope that helps
bluestar

[absynthe]

The double curve is the one that comes on the key blanks? The single control pins slide along the third curve that is added on (also deeper I think)?

What is the purpose of having the double curve? It seems like all of the sliders just need to be a certain height. Why not just have one curve that brings them to the correct height. Is it because the curve would have to change height too dramatically to allow for a slider that would sit low be next to a slider that sits high? Maybe that would make the key possibly jam when it went in?

Also.. some of the sliders I have seen seem to have multiple correct positions.. I believe for master keying. Do standard 3KSs only have single correct positions? It seems like a house lock would not need to have extra correct positions as you would lose some of the security of the lock (even though not by much practically)

[bluestar]

yes, the double curve comes on the key blanks - see it as a sort of profile. You can order a copy only from the locksmith you bought the lock from or from EVVA directly. But you could also order a lock directly from the factory (which can choose from all possibilities).

Standard 3KS have only one possible position, plus some fake ones.

The double curve is for being able to have two locking informations at one position. The sliders are arranged in pairs, while the left(right) slider controls the double curve, the right(left) slider controls the single curve at the same position on the opposite side of the key. And as the key has to fit both ways, the curves have to be identical on both sides of the key.
If you had just one curve, you would have only information for six sliders (or you have a key and lock twice as long or a non-reversible key with different curves on both sides).

It is a bit hard to describe it just with words, but I hope I could help you a bit
bluestar

[bluestar]

PS: The double curve on the blanks is similar to the Assa Twin Sidebar Code. Except you can't bump a 3KS

[absynthe]

So in the lock you would always have 6 double control pins and 6 singles? Or another way would be three doubles and three singles one each side? And a double slider would always be across from a single?

If that is correct then it makes sense now. Thanks for the help guys.

[bluestar]

Yes, on each side there are three sliders with two control pins and three sliders with one, alternating. So if the right side ist OTOTOT the left side ist TOTOTO.

You're welcome
bluestar

[greyman]

There's two sorts of sidebar pins, one fits the deep track the other fits the upper and lower tracks. My book has more detail on this

[NKT]

Not sure why no-one has pointed out the sliders have springs? They are not passive.

Trust me, I drilled one out today, and there was definitely springs in there. Plus, passive dropping is bad for things like locks which often get mounted upside down.

[JK_the_CJer]

Not sure why no-one has pointed out the sliders have springs? They are not passive.

Trust me, I drilled one out today, and there was definitely springs in there. Plus, passive dropping is bad for things like locks which often get mounted upside down.

This is wrong.

There are no springs pressuring the sliders, they are loose. It makes no difference what the orientation of the lock is because the tracks in the key will scoop the slider tabs up into the tracks from any possible starting position. The springs you saw while drilling must have been the sidebar springs (that bias the sidebar outward).

[n2oah]

There's two sorts of sidebar pins, one fits the deep track the other fits the upper and lower tracks. My book has more detail on this

Yes. Take a hold of the bow of the key and face the grooves toward you. Now rotate the key 90 degrees toward you so you're looking "into" the grooves. You'll notice that the two grooves in the middle of the key are deeper than the four that start near the outside of the key.
Pictures of a 3KS blank are located on page 6. http://toool.nl/images/f/f9/Cutaway1.pdf

[weerwolf]

Not sure why no-one has pointed out the sliders have springs? They are not passive.

Trust me, I drilled one out today, and there was definitely springs in there. Plus, passive dropping is bad for things like locks which often get mounted upside down.

No , the springs aren't for the sliders. The springs are on the sidebars. There are 2 springs on each of the sidebars.

[SnowyBoy]

Not sure why no-one has pointed out the sliders have springs? They are not passive.

Trust me, I drilled one out today, and there was definitely springs in there. Plus, passive dropping is bad for things like locks which often get mounted upside down.

As was said, they are passive and gravity makes them all slide to the bottom of the case further strenghening against pull out attacks due to the grooves that line the case. If the sliders were to not fall down in position when the key is not inserted, all that would be defending the lock from pull out is the circlip on the back, but because all 12 sliders fall down they almost triple the pull out rating in joules.

Nice locks, I've cut two away, one with ah alf cylinder to show the sliders from the inside. I tried to pick it with just 4 sliders and I lost patience with it.

[SnowyBoy]

Forgot to say that even if a total eeejit installs this lock upside down it will still perform its intended purpose and the sliders will fall the other way. Even if it is installed on its side, retracting the key resets the sliders in a fasion that leaves most of them still doing their job.

To test that, just try and extract a cylinder from one after just removing the key..... it won't work! You have to set each slider dead centre in the key way in order to extract.