Nov 12

Why is a Rim called a Rim?

Someone new to our industry recently asked me why a Rim Panic Device was called a “Rim”.   Not as self explanatory as a vertical rod to be sure.  I explained that I wasn’t sure myself but I would find out.  I turned to Bill Jahns, our hardware guru at Design and asked him “why is a rim called a rim”?  He had this to say:

“I think it got it’s name from rim locks because they are surface mounted and the latch is in the same position on the rim of the door.” Here are some images of rim locks.  He added that both rim locks and rim exit device are commonly operated by rim Cylinders.






No one else I asked seemed to be able to add anything to this mystery.  Please comment below if you can confirm this theory or have another.

1 comment

  1. Martin B (aka Laux Myth)

    I had heard the same. However, also heard it was because it took a rim cylinder. And a rim cylinder is called that since the friction at the rim of its face holds it from rotating. (In the best of all possible worlds.) However, this does not make much sense for EO (exit only) installation since it takes no cylinder at all and you still call the device a rim exit.

    In a twist of sorts, some exit devices which are casually called rim devices use trims which take a mortise cylinder.

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