This has been called a "B B Binks" cylinder or a Brinks cylinder - I have heard both and they refer to this - a cylinder in which one key can only turn one way. Either to lock or unlock a lock. It can not go both ways - although the "master" can go both ways.
On the right is the cylinder in question. It is made into a Schlage rim cylinder - I could have used anything, but this is my demo unit. The key on the left only turn left, the key on the right only turns right. the one in the middle goes both ways. How is this possible?
It is in the internal reworking of the lock. What you need to do is to file a pocket .060 deep at one point and drop the key 2 numbers at that point. For example - On the left turning key, the last cut on the master is 4, and the left turning key is 6. This gives you the ledge to keep the key from turning the other way. I could post the thing out of the Corbin service manual, but I won't. Know the cut or shelf only goes half way - that is from the center to the direction you want it to go. Normally one end of the plug gets the left, and the other end gets the right. this gives us both to use.
Where did this come from? Detention hardware. Folger Adams, Southern Steel and Western Wire all have this feature available for detention hardware. this is an extension of that application. For those who need to know LTR (long term residents) in the system do not have detention hardware on the door, they have normal hollow metal hardware, usually mortise locks and the resident has a key for their own unit. The key only turns to let them in, not throw the deadbolt. the deadbolt is thrown either by the electrical panel at the control point or by the detention officer using the master to throw it. Which means that the resident key is a Brinks key - and thus this came about.
Where this has an application is in stores who want to lock up at night, but not let the person locking up back in. So if you have a high value business like liquor or a "C" store and you want to lock up and the owner does not do it, he needs to know that the place is secure. So the night man can only lock up and not unlock the door. If there is a loss either the night man did not lock up properly, or .... The owner has a master which can both lock and unlock the door, just like the detention hardware.
The other key? Well that is another story, and maybe later --
Pix from our web page ..
Sinifar
. This is really cool and looks like a fun project.
