Timothy wroteFind this a while back. Reason I post this so will have an idea of what Corbin and Russwin Pins. This is one reason of why so hard to pick and impression key….Timothy…..
BBE’s late friend and associate A.J. Hoffman with others wrote the Corbin Russwin Cylinder/Keying Parts & Service Manual which explains the use of ball bearing bottom pins on page 55:
You will find a ball bearing at the bottom of pin stacks in some or all chambers of Corbin and Russwin cylinders manufactured from about 1902 until the mid 1960s. The oldest cylinders have the ball in every chamber. The number of balls was gradually reduced until only the front two chambers had them. The purpose of the balls was to reduce wear on the pins. As harder brass became available, wear became less of a factor, so usage of the balls in the pin stacks was eventually phased out. However, the balls themselves are still available because they are used in other Corbin Russwin products. If you have a problem with pin wear in high traffic cylinders, consider rekeying the cylinder with these balls. They are compatible with all current Corbin Russwin cylinders except high security. Order P/N 159F36-7 stainless steel ball in multiples of 100 from your Corbin Russwin distributor. The diameter is .116″ so select the size of the pin over the ball accordingly. Note: Do not use a ball in every chamber. This creates a security risk because a bypass tool called a “lock comb” can be used to raise all balls to the shear line and operate the cylinder.
On a personal note, I have observed that the ball bearings can develop flat spots after decades of use making the key harder to turn since the pin stack doesn’t quite reach the shear line under these circumstances.
The Service Manual referred to above is available on the Internet in pdf format and contains a wealth of technical information about the various Corbin Russwin keying systems:
http://content.assaabloyusa.com/cs/groups/external/@shared/@marketing/@us/@corbinrusswin/documents/techmanual/mdaw/mdew/edisp/aadss1010134.pdf
Pete Schifferli
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