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  1. #1
    Join Date
    Jan 2011
    Location
    Mid Michigan
    Posts
    139
    Country: United States

    Default Yale Bicentric padlock

    I wanted to reply/add to your point of information post Pete.

    "Point of Information-

    The Yale Bicentric cylinder was an early answer to avoiding the problem of key interchange for masterkeyed locks. Most pin tumbler masterkeyed locks use a "split-pin" system and as a result many unintended keys may operate the lock. As an example, a 6-pin cylinder with a single master key disc in all six chambers could be operated by 64 different keys! The Bicentric cylinder has two plugs, neither of which is masterkeyed. One, normally the upper plug, is controlled by the master key while the other plug, usually the lower one, is controlled by the change key. The lock can be operated by the use of either key in its own plug. Thus it is not dual custody in the sense that both keys would be needed to open the lock like a safety deposit box."
    Click image for larger version. 

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    While the majority of these locks I see are opened by either key, they did make a dual custody configuration with 'guard' and 'change' cylinders. I've included a couple pictures of one I have. The guard key must first be turned before the change key will open, neither will open the lock by itself.
    Click image for larger version. 

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  2. #2
    Join Date
    Oct 2010
    Location
    Tonawanda, NY, USA
    Posts
    900
    Country: United States

    Default

    Quote Originally Posted by bbcci View Post
    I wanted to reply/add to your point of information post Pete.

    Click image for larger version. 

Name:	duplex2a.JPG 
Views:	38 
Size:	111.6 KB 
ID:	5654
    While the majority of these locks I see are opened by either key, they did make a dual custody configuration with 'guard' and 'change' cylinders. I've included a couple pictures of one I have. The guard key must first be turned before the change key will open, neither will open the lock by itself.
    Click image for larger version. 

Name:	duplex1.JPG 
Views:	37 
Size:	38.6 KB 
ID:	5653

    Interesting, thanks for sharing. I wonder if that dual custody feature was available on mortise and/or rim cylinders as well?

    Pete Schifferli
    Tonawanda, NY

  3. #3
    Join Date
    Nov 2005
    Location
    Seattle WA
    Posts
    1,327
    Country: United States

    Default

    There are locks that require two keys. They are rare as I have only seen one in 22 years of working on locks. It was on a military base as that would be the place I would expect it.

  4. #4
    Join Date
    Jun 2008
    Location
    Temperance, Michigan USA
    Posts
    132
    Country: United States

    Default

    bbcci, is this padlock for sale/trade?

    Mike
    The Amazing Michael~Escape Artist/Scuba Diver/Locksmith/Lock, Handcuff, and Restraint Collector......and one HELL of a model American! =)

  5. #5
    Join Date
    Jan 2011
    Location
    Mid Michigan
    Posts
    139
    Country: United States

    Default

    Quote Originally Posted by amazing01 View Post
    bbcci, is this padlock for sale/trade?

    Mike

    Morning Mike, Not at the present time, but I will give you a heads up if that changes. I thought about it and you when I saw your wanted post.
    Bill

  6. #6
    Join Date
    Jun 2008
    Location
    Temperance, Michigan USA
    Posts
    132
    Country: United States

    Default

    Fair enough Bill. =)

    Mike
    The Amazing Michael~Escape Artist/Scuba Diver/Locksmith/Lock, Handcuff, and Restraint Collector......and one HELL of a model American! =)

  7. #7
    Join Date
    Dec 2009
    Posts
    1,485
    Country: United States

    Default

    Can the mortise lock be field-configured to dual custody or was this a factory-only option?

  8. #8
    Join Date
    Jan 2013
    Posts
    714
    Country: United States

    Default Yale Bicentric Padlock

    They could be but not sure because I never seem these lock any where. I'm sure someone on this forum may know the answer.

  9. #9
    Join Date
    Nov 2005
    Location
    Seattle WA
    Posts
    1,327
    Country: United States

    Default

    Yale's Bicentric was just a means to make truely LARGE master key systems. You could on one keyway have all the masters and the other just change keys. and they both would be different keyways. So as you can see you could have say 4000 master keys and about 500,000 change keys for each change key keyway. So if you had a campus you could issue out keys to each room on campus and still have a master that had no direct connection to the master, unlike master key systems of today.

    It's downfall was that you couldn't do it outside of large locks so once the modern levers came into use the use of this type of cylinder also fell.

  10. #10
    Join Date
    Aug 2012
    Location
    USA
    Posts
    192
    Country: United States

    Smile Yale-Bicentric-padlock

    Thanks to ALL who responded to my question about a this type of lock.
    Since I already have a "master/change key.... YALE padlock.........
    My search is for a "dual custody" lock showing at the plug's = GUARD & CHANGE, yes?
    Looks like a difficult lock to find, from the various answer's that I received
    thank you again, Donnie

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