Mortise locks have been around for a while. These locks are reliable as well as varied in how they are constructed. Mortise locks have considerable longevity, which is why knowing how to repair and maintain one is helpful information. Mortise locks are unique in how they are built. They can even be taken apart and put together again. Mortise locks tend to work better in particular situations, so it’s good to know about their usage.


You’ll often see mortise locks in use in commercial spaces. This is because these locks are strong and can withstand a lot of use. In fact, these locks are designed to take a toll of wear and tear. The internal mechanisms of mortise locks are made to be easily repaired and serviceable. Overall, these hardy locks can stand the test of time. Because mortise locks are often in use over an extended period of years, there does come a time when parts of it may need to be fixed or replaced. Mortise locks that come along with an older home are likely in good condition for continued use, even for many years to come.

How They Work

Mortise locks are different from regular cylinder locks. The lock is often installed inside the knob or handle itself. Mortise locks are built out of many different parts put together in a pocket (or mortise) of the door. Here are the components that make up a mortise lock:

  • Lock Body – The shell that encompasses the lock parts.
  • Handle/Knobs – This is the part you turn in order to use the lock.
  • Through Spindle – This rod connects the handles/knobs through the door and lock body.
  • Lock Cylinder – This secures the door into the lock – when a key is inserted, the door opens.
  • Strike Plate – This part is screwed to the doorway and lines up with the bolt of the lock body.

Other possible components:

  • Escutcheon Plates – Known also as rose plates. This little metal fixture  brings the lock and handle together.
  •  Hard Collars – These protect the lock from being pried into.
  • Face-plate – This covers the internal mechanisms of the lock on the side that faces the strike plate. 
  • Day/Night Switch – You can use this switch to lock the door from the outside while being unlocked on the inside.

Mortise locks are harder than other locks. This can be felt in the bolts sheer size and weight. These locks are installed into the mortise (pocket) of the door. The individual components are then installed one at a time to complete the lock.


Mortise locks are often older, so it’s good to service one if you’d lie to put it into new use. Sometimes it’s necessary to clean the rust or re-do some of the bolt work, as these locks have probably been in use for many years before you came across them. Mortise locks can be disassembled and reassembled for servicing. There are several ways to remove rust in mortise locks, including the use of vinegar, polish and electrolysis.


Like any lock, mortise locks have their common glitches and stumbling blocks, especially those that have been used heavily. The handle or knob have been known to even fall right off! In this case your spindle probably needs replacing. It’s likely that the current spindle has been worn down from use, and it no longer screws as well as it used to.

Sometimes the key fails to work on old mortise locks. In this case, the cam of the lock might be broken and in need of replacement. You may as well replace the entire cylinder in this case, as extensive wear in one area probably means rough wear in another. Still, the cam is probably the direct cause of this issue. If you’re not so sure, you’ll need to open the lock body. To do this, you’ll first need to remove the latch cover. This is likely being held down by a few screws. Be careful – opening the latch cover can cause the components inside to spring out – sometimes right into your face! Be sure to take a picture of the inner mechanisms of a mortise when you open it. You’ll be able to put it back together after you take it apart for servicing.

Another reason why your key won’t work could be that the lever is sagging. Your spring may be weak or damaged. You should closely consider the largest spring, located against the hub of the spindle. If the spring isn’t vertical, it’s probably malfunctioning, causing the key to not work.


Mortise locks are the go-to for businesses. Antique mortise locks can also be found on the doors of older homes. Instead of replacing these for newfangled ones, why not have them serviced in order to retain some of the home’s character? A working mortise lock does an exceptional job from a security standpoint as well. Make sure that safety is a priority when servicing and installing these locks. The methods suggested for removing rust should be carried out carefully – no messing around. Even if you find yourself confused by all of the bits and bobs, don’t give up. The best way to build a working understanding of a mortise lock is to take one apart and have a go at it. However, mortise locks should be handled with confidence and care. When in doubt, it’s always a good idea to call in the help of a professional commercial locksmith. If you don’t trust yourself with the mechanisms of a mortise lock, or you’re just not interested in getting tangled up with one, a locksmith can bring essential clarity to the situation. A lock that has not been installed properly poses a danger to your safety, especially if these are perimeter doors. At the end of the day, locks are made to aid protection – they’re not fun and games. Put your home security first, and maybe take a chance on a good ol’ mortise lock sometime soon!

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