Interchangeable/Removable Cores: How Do They Operate?

Feb. 15, 2005

Interchangeable/removable core lock mechanisms have been around since the early 1920s. Generally speaking, the identifying difference between the interchangeable core and the removable core is the interchangeable core can be used in locks from different manufacturers, using the same space and depths. Removable core lock mechanisms are proprietary to specific lock manufacturers using their specific space and depths. Each core type has its advantages and disadvantages, as we shall see throughout this article.

The interchangeable/removable core lock mechanisms were developed to allow personnel having no knowledge of how locks operate to conveniently and inexpensively rekey a lock. This concept satisfies the needs of commercial and institution customers with large rates of employee turnover. To evolve with the increased need for security, lock manufacturers have introduced key control and high-security features to the interchangeable and removable core lock mechanisms.

The figure "8" (Best/Falcon) interchangeable core is the more used lock mechanism. Beginning with Best, this lock mechanism has been incorporated into the following popular lock manufacturers: Arrow, Best, Corbin Russwin, Eagle, Falcon, Kaba-Ilco, Lockwood, Medeco, Sargent, Schlage, and Yale. In addition, manufacturers such as KSP produce interchangeable cores for use in the above brands of locks.

The interchangeable/removable core lock mechanisms function similarly. The master keys and change keys align the pin tumblers at the operating shearline of the plug. The control key operates a second shearline, the control shearline or an additional component of the core assembly in order to release the core from the housing. Cores can be held within the housings using a lug, pin, or plate retainer.

The control key may have the same length or longer blade in order to release the core from the housing. Depending upon the design of the core mechanism, one or more pin chambers acts as the control.

NOTE: The control key should NEVER operate the lock mechanism. The master/change keys should NEVER remove a core assembly from the housing.

The interchangeable core lock mechanism has a completely separate operating shearline and control shearline that are part of all the pin chambers.

There are three current, basic styles of the removable core lock mechanisms when discussing removal of the core assembly. For style one, the control shearline contains some of the operating pin chambers. The second style has an actuator pin at the rear of the core. The second style uses a longer key. This style key must also be cut to contain the top level master key depths. The reason the control key in the second style must be cut the top level master key depths is in order to operate all of the cores.

The two charts cover the specific interchangeable/removable core lock mechanisms.

View Chart 1

View Chart 2

For more information, contact your local locksmith wholesaler or:

  • Arrow Lock , 325 Duffy Avenue, Hicksville, NY 11801. Telephone: 800-221-6529. Website: .
  • Best Access Systems , 6161 East 75th St, Indianapolis, IN 46250. Telephone: 317-849-2250. Website: .
  • Corbin Russwin , 1902 Airport Road, Monroe, NC 28110. Telephone: 800-438-1951. Website: .
  • Falcon Lock , 2315 Briargate Parkway, Colorado Springs, CO 80920. Telephone: 800-266-4456. Website: .
  • Kaba-Ilco , 400 Jeffreys Road, Rocky Mount, NC 27804. Telephone: 800-334-1381. Website: .
  • Kaba Access Control , 2941 Indiana Ave, Winston-Salem, NC 27105. Telephone: 800-849-8324. Website: .
  • Lloyd-Matheson (Lockwood) , P. O. Box L, Charlestown, NH 03603. Telephone: 603-826-5777.
  • Medeco High Security Locks , 3625 Allegheny Drive, Salem, VA 24153. Telephone: 800-675-7558. Website: .
  • SARGENT Manufacturing Company , 100 Sargent Drive, New Haven, CT 06536. Telephone: 800-727-5477. Website: .
  • Schlage Lock Company , 2315 Briargate Parkway, Colorado Springs, CO 80920. Telephone: 800-847-1864. Website: .
  • Yale Security Group , 1902 Airport Road, Monroe, NC 28110. Telephone: 800-438-1951. Website: .

A1 CapSaver Press

The A 1 Security Manufacturing Corporation CapSaver™ Press, part number CAP5, is designed to cut, insert, and seat core caps into figure "8" style interchangeable cores using individual core caps. The A 1 CapSaver Press eliminates fitting and seating each core cap individually. Capping the figure "8" interchangeable cores is accomplished in one downward operation of the CapSaver Press handle.

The combinated interchangeable core to be capped is loaded into the CapSaver Press. The CapSaver strip is loaded into the holding block. As the handle is depressed, the core caps are cut from the CapSaver Strip. The core caps move down to the interchangeable core. As the handle comes to a stop, the core caps are press fit into each of the pin chambers until they are just within the body of the interchangeable core. Raising the handle releases the core, which is now ready for installation.

The core caps are cut from an A 1 CapSaver strip. Each CapSaver strip can be used to core cap four figure "8" interchangeable cores. The brass CapSaver Strips are available in boxes of 250.

For more information, contact your local locksmith distributor or A 1 Security Manufacturing Corp., 3001 West Moore, Richmond, VA 23230. Telephone: 877-725-2121. Fax: 804-359-9415. Website: .