Here’s a fantastic video from Lee Harvey of Door Hardware Simplified explaining what a mortise door lock is. Below the video we have include an audio transcript of the video:
I’d like to talk about mortise locks. Mortise locks is a type of lock set that’s used in the commercial industry as far as for heavy duty, high frequency use applications.
The mortise lock is quite a bit different than the cylindrical lock, or board type lock that we know it, where the cylinder is installed in the lever, and the latch bolt connects to the chassis. It’s different than a unit lock, or what we refer to as a pre-assembled lock, where this lock comes out of its box, and simply is installed in a cutout in the door for that notch.
The mortise lock, as you will see, comes with many different components. It has the mortise body that we are showing now. It has escutcheon type trim plates or rose plates that fit on the outside and the inside of the door. It comes with its levers the outside lever, the inside lever. Together they’re connected through a through spindle onto the door through the mortise lock case itself as well as a separate cylinder.
As opposed to a cylindrical lock, these pieces are all disassembled when it’s in the box, and it has to be assembled in the door properly and in a correct manner, of course, using the manufacturer standard fasteners that come with it. It also comes with a strike plate. Once the lock set is installed in the door, the strike is simply installed on the jam to allow the latch bolt, to simply engage into that strike. You’ll notice on this mortise lock set that there are a lot more parts associated to it. The parts are heavier duty, more massive, because of the type of applications that this lock is designed for.
You will have the hubs where the spindle passes through. They’re spring loaded to power the lever that’s in this lever, so it doesn’t sag or droop. We have the latch bolt. We have the auxiliary dead locking latch. It also, depending on the function that you decide to install, will have a deadbolt. Primarily those are the functions and these are the internal parts or mechanisms that’s made into it.
This is the mortise lock case that you would get from the manufacturer.
By installing it into a pre assembled door, already prepared for this mortise lock, you’ll notice that the mortise lock simply engages into the edge of the door, into the cavity that was designed to receive that Mortise lock.
Once that’s in place, you then are able to install your escutcheons, or outside trim, being an escutcheon or a rose type trim.
This particular sample has an escutcheon trim. If you’ll notice that this door is prepped for that plate to simply install on it. It has a place for the cylinder to be installed through. It also has an inside plate that fits on the inside of the door.
It’s a matching escutcheon type. Once all this is installed, and the cylinder is screwed into the lock set, then you’re able to fasten this lock and secure it in its place.
Once that’s completed, we install the final item. This is called a face plate or a scalp. That simply covers up all of the fasteners and the screws that are used in putting that lock on the door.