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  1. #11
    Join Date
    Nov 2005
    Location
    Seattle WA
    Posts
    1,327
    Country: United States

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    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.

  2. #12
    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

  3. #13

    Default

    Quote Originally Posted by Donnie View Post
    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
    Here is some catalog information that may help. It was a lot bigger in Paint.
    BBE.
    Click image for larger version. 

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  4. #14
    Join Date
    Jan 2013
    Posts
    714
    Country: United States

    Default Yale Bicentric padlock

    Well just found something that maybe everyone would like to see. The first one should be close but as they call it Duplex or Master Key Lock. The second one it double cylinder as it said by using for Hotel Room.
    Attached Files Attached Files

  5. #15

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    Quote Originally Posted by Timothy View Post
    Well just found something that maybe everyone would like to see. The first one should be close but as they call it Duplex or Master Key Lock. The second one it double cylinder as it said by using for Hotel Room.
    It is very interesting that those patents call it a 'duplex' mechanism because Yale did produce door locks with two separate cylinders on the same side of the door from 1878 until 1889 which was marketed under the name Yale Duplex. The purpose of that two cylinder lock was to offer master keying for man doors. Up until 1878 Yale had used what is called the 'shoebox' method of master keying today and it was noted in catalogs that the number of KD locks was virtually unlimited. Naturally that came back to bite them pretty hard in the form of interchange in the field and the 1878 catalog did not offer master keying except via the duplex locks. In 1889 catalog number 12 offered regular master keying with 1 master key and 16 change keys. That is because they had discovered scientific master keying using the Rotating Constant Method with a 1 in 5 pattern.

    While I was Key Records Manager for Yale I tried to find one of those 1889 system records but alas all key system records prior to 1900 had been destroyed preceeding the move of headquarters from Rye, NY to Monroe, NC. The English division may have still had some records from earlier days but I never got the opportunity to get there and look. After the purchase by Williams Holding I am sure any earlier records were very likely destroyed .
    BBE.

  6. #16
    Join Date
    Sep 2004
    Location
    Devon UK
    Posts
    3,117
    Country: UK

    Default

    SO the rotating constant was discovered in the 1880's?
    That is historical knowledge which no amount of googling would find out!

  7. #17

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    Quote Originally Posted by Tom Gordon View Post
    SO the rotating constant was discovered in the 1880's?
    That is historical knowledge which no amount of googling would find out!
    Correct on both counts. However, it has been in my Master keying book "Master Keying by the Numbers" since 1991.
    BBE.

  8. #18
    Join Date
    Jan 2013
    Posts
    714
    Country: United States

    Default Yale Bicentric padlock

    Found some more of Yale Patent Lock as how they came up with 'duplex' Lock.....
    Attached Files Attached Files

  9. #19
    Join Date
    Nov 2013
    Posts
    6
    Country: Canada

    Default

    Quote Originally Posted by Timothy View Post
    Found some more of Yale Patent Lock as how they came up with 'duplex' Lock.....
    Here are a few pics of the rare dual custody padlock by Yale.
    Requires both keys to open this padlock.
    One key is turned first then the other to open.
    I picked this up on EBay a number of years ago, I paid through the nose for it and have not seen another one for sale since.
    i just HAD to have it.
    mike
    Attached Thumbnails Attached Thumbnails image.jpg   image.jpg   image.jpg   image.jpg  

  10. #20
    Join Date
    Jan 2013
    Posts
    714
    Country: United States

    Default Yale Bicentric Padlock

    Gizmo
    Nice padlock with original keys as I'm sure you pay good price for this padlock. I have see some that doesn't have the original key as people still pay the price to high. This is one reason as buying any padlock for whatever price should alway see if it come with original key if not than that padlock not worst more than they should be. I have see some padlock cost over $500.00 to $1000.00 doesn't come with original keys....Timothy....

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