Mortise sash locks combine a spring-operated latchbolt and a key-operated deadbolt inside one recessed lock case. The latch keeps the door closed during normal use, while the deadbolt provides additional security when the door is locked. This dual function makes mortise sash locks a common choice for apartment entrances, offices, hotels and other commercial interiors.
The lock case is installed in a pocket cut into the door edge. Its latchbolt engages automatically when the door closes, while the deadbolt is extended by a cylinder, key or thumbturn.
A standard assembly normally contains:
Spring latchbolt
Security deadbolt
Lever follower
Internal transmission parts
Lock case and forend
Strike plate
Cylinder or key operation point
The handle spindle passes through the follower. Pressing the lever rotates the follower and retracts the latchbolt. The deadbolt remains independent unless the selected lock includes a special escape or combined-retraction function.
The commercial sash lock mechanism supports two separate door actions. During everyday passage, users operate the lever to withdraw the latch. When additional security is needed, the key turns the cylinder cam and moves the deadbolt into the strike.
Some lock designs allow the cylinder to withdraw both the deadbolt and latchbolt during the final part of the key rotation. This can provide convenient entry without requiring the user to operate the lever separately. Buyers must confirm this function because it is not standard on every model.
A sash lock includes both a latchbolt and deadbolt and is generally paired with lever handles. A mortise deadlock has no spring latch and normally works with a key, thumbturn or pull handle.
Sash locks are more suitable for frequently used doors that need to remain closed when unlocked. Deadlocks are often selected for storage rooms, service doors or entrances where a separate door-closing method is available.
Backset is measured from the door edge to the operating center of the cylinder or follower. Center distance refers to the spacing between the lever follower and cylinder center. European commercial models frequently use center distances such as 72 or 85 mm.
The following information should be checked before ordering:
Door material and thickness
Required backset and center distance
Forend length, width and corner shape
Latch direction and door handing
Cylinder profile and length
Lever spindle dimensions
Strike plate configuration
A reversible latch can simplify inventory for left- and right-opening doors, but the reversing method should be confirmed before installation.
Lock components made from SUS304 stainless steel provide dependable resistance to wear and corrosion. Galvanized steel cases protect internal mechanisms while controlling production cost.
Commercial projects may require compliance with EN 12209, which classifies mechanical locks by usage, durability, fire suitability, corrosion resistance and security. Locks installed on fire doors also need supporting evidence for the relevant door assembly.
D&D offers sash lock configurations for wooden, metal and fire-rated doors, with selected models tested for 200,000 operating cycles. Finish choices can include satin stainless steel, polished stainless steel, brass tones, black and PVD finishes.
Buyers should submit a door schedule showing quantities, lock functions, dimensions, finishes and keying requirements. Samples can then be checked against the actual door, cylinder, handle and strike preparation.
A qualified sash lock wholesale manufacturer should maintain consistent internal tolerances across production batches. Stable dimensions simplify installation, support replacement programs and reduce the risk of handles, cylinders or strike plates failing to align on site.
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