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Mortise locksets: cases, functions and trim

A mortise lockset is specified by function, backset, handing, trim and cylinder.

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The short answer

Mortise locksets

A mortise lockset is specified by function, backset, handing, trim and cylinder. The lock case sits in a pocket cut into the door edge, so a replacement has to fit the pocket and the holes already in the door.

How to choose

What actually decides the part number

FunctionMortise locks come in the same kinds of function as cylindrical locks, passage, privacy, office, classroom and storeroom, and a mortise case can also throw a deadbolt from the same body. The function decides the case.
Case and door prepMortise cases differ in size and backset between manufacturers. A different brand usually means recutting the door, so replacing like for like is the default.
HandingMany mortise locks are handed at the factory and cannot be reversed in the field. The hand is read from the outside of the door, the keyed or secure side.
Trim and cylinderThe outside trim is a lever with a rose or an escutcheon, and the cylinder is a mortise cylinder whose cam has to suit the case. ANSI/BHMA A156.13 covers mortise locks.

Before it ships

What we confirm with you

Confirmed in writingFunction, backset, hand, door thickness, trim style, finish, and the cylinder and keyway.
AvailabilitySargent 8200, BEST 45H and 47H, Hager 3800 Series and Baldwin Estate mortise sets, with lock bodies, fronts, trim and cylinders, about 2,600 part numbers. Few lines are stocked. Most are special order from the manufacturer, typically 4 to 6 weeks and sometimes longer, and the quote states it.

Related categories

Compare without going back

Cylindrical locksetsFunctions, backsets and grades Exit devicesWhat you need to specify Electrified hardwareStrikes, maglocks and electric locks

All eight guides

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