How to determine the length of a Mortise Cylinder

– by Jason Brown

    One of the questions that everyone asks when they want to buy a mortise cylinder is how to correctly determine the length of the cylinder.  In most cases, you’ll have a Mortise Cylinder that you’ll be replacing so that it is easier for you to tell the length of the one you have and the tailpiece you need. But what if you don't have a cylinder, what can you measure?

    So, How do I determine the length needed?

    The length of a mortise cylinder is determined from underneath the head to the outside of the cam (see illus below). 

      Mortise cylinders should reach the center of a door but should not screw in far enough to touch the cylinder or turn knob on the reverse side of the locking unit.  


What is Master Key and Grand Master Key?

    - Master Keyed (MK) – A system consisting of several cylinders and each has a unique key. Within the system, there would be one Master Key (or pass key) that will operate all cylinders within the system.

    - Grand Master Key (GMK) – This is an extension of a master key system where the cylinders are divided into two or more groups. Again each individual cylinder has its own unique key. Each group would have its own unique Master Key and to make this a Grand Master key, there will be one Grand Master Key (or pass key) that will operate all cylinders.


What do the abbreviations for KD and KA mean?

- KD (Keyed Different) - An individually keyed cylinder operated by its own unique key.

- KA (Keyed Alike) - Two or more cylinders operated by the same key. This is ideal for residential applications (i.e. front and back door).


Mortise Cylinders come in 10 different sizes:

3/4"

1'

1-1/8"

1-1/4"

1-3/8"

1-1/2"

1-5/8"

1-3/4"

1-7/8"

2"

Custom Length upon request.


The part numbers are:

    - C7124-KD  3/4" Long, LOCKWOOD LA Keyway, Keyed Different

    - C7124-KA  3/4" Long, LOCKWOOD LA Keyway, Keyed Alike

    - C7165-KD  1" Long, SCHLAGE C Keyway, Keyed Different

    - C7165-KA  1" Long, SCHLAGE C Keyway, Keyed Alike

    - C7185-KD  1-1⁄8" Long, SCHLAGE C Keyway, Keyed Different

    - C7185-KA  1-1⁄8" Long, SCHLAGE C Keyway, Keyed Alike

    - C7205-KD  1-1⁄4" Long, SCHLAGE C Keyway, Keyed Different

    - C7205-KA 1-1⁄4"Long, SCHLAGE C Keyway, Keyed Alike

    - C7225-KD 1-3⁄8" Long, SCHLAGE C Keyway, Keyed Different

    - C7225-KA  1-3⁄8" Long, SCHLAGE C Keyway, Keyed Alike

    - C7245-KD  1-1⁄2" Long, SCHLAGE C Keyway, Keyed Different

    - C7245-KA  1-1⁄2" Long, SCHLAGE C Keyway, Keyed Alike

    - C7265-KD  1-5⁄8" Long, SCHLAGE C Keyway, Keyed Different

    - C7265-KA  1-5⁄8" Long, SCHLAGE C Keyway, Keyed Alike

    - C7285-KD  1-3⁄4" Long, SCHLAGE C Keyway, Keyed Different

    - C7285-KA  1-3⁄4" Long, SCHLAGE C Keyway, Keyed Alike

    - C7305-KD  1-7⁄8" Long, SCHLAGE C Keyway, Keyed Different

    - C7305-KA  1-7⁄8" Long, SCHLAGE C Keyway, Keyed Alike

    - C7325-KD  2" Long, SCHLAGE C Keyway, Keyed Different

    - C7325-KA  2" Long, SCHLAGE C Keyway, Keyed Alike