This application came across my desk last week and for the life of me I couldn’t think of where someone would use it. I don’t remember ever being asked for a rim cylinder with a thumbturn, and people ask me for all kinds of random things.
For anyone who has wondered about the difference between a rim cylinder and a mortise cylinder and which one to use where, it basically depends on what kind of locking hardware the cylinder will be used with. Mortise cylinders are threaded, and have a cam on the back. Rim cylinders attach with screws and have a tailpiece on the back. The lock/panic hardware manufacturer’s catalog will show which type of cylinder is needed.
Last week one of the Ingersoll Rand specwriters was looking for a rim cylinder with a thumbturn. Thumbturn cylinders are typically mortise cylinders and are used with mortise deadbolts, narrow stile locks, etc. Schlage offers a thumbturn rim cylinder as a special product (product #XB11-979). It was designed for use on a Von Duprin 98/99 exit device with the -2 option (ex. 99L-2).
The -2 option is a cylinder on the active head of the panic device, which can be used to lock or unlock the outside lever handle (or other trim). The Von Duprin rim device uses a rim cylinder for this function, and the mortise device uses a mortise cylinder. The thumbturn rim cylinder allows the locking/unlocking to be accomplished without a key, for areas where the convenience of a thumbturn is preferred over the security of a key cylinder. The thumbturn position also gives visual confirmation that the lever handle is locked.
Any other ideas about where a thumbturn rim cylinder would come in handy?