Indian mortise handle set, rim nightlatch and cylindrical lock
India is the clearest example of why a retrofit cannot be designed per country. Three incompatible interfaces share one market: a euro-profile mortise set with a 50 mm backset, a rim nightlatch with a 69 mm backset, and a cylindrical lock with a 60 mm backset. A single adapter library has to cover all three, and the backsets do not overlap.
Also called: Godrej-type mortise · Indian rim lock · 9 inch lock body
Anatomy
- Mortise set: a 240 mm (9 inch) euro-profile lock body, a euro-profile pin cylinder, and a handle rose set
- Rim nightlatch: a surface case with a profiled latch bolt, a rim cylinder through the door, and a knob inside
- Cylindrical lock: a bored lockset, the same family as the North American A156.2 set
- Commonly 5-pin brass tumbler cylinders with three keys
Parameters to measure
Measure in this order: Backset (Dornmaß) → Key profile → Door thickness → Faceplate width × length → Cylinder total length and halves (e.g. 35/35)
| Parameter | Typical values | Tolerance that still fits | How to measure |
|---|---|---|---|
| Backset (Dornmaß) | 50 mm on mortise handle sets, 69 mm on rim nightlatches, 60 mm on cylindrical locks | None — the three values do not overlap, so identifying the type comes first | Door edge to the centre of the keyhole or cylinder. |
| Door thickness | 28–40 mm for mortise sets; rim nightlatches accept 25–60 mm | Wide on rim locks, narrow on mortise sets | Measure the leaf at the lock. |
| Faceplate width × length | Mortise lock body commonly 240 mm (9 inch) long | Record the actual length | Measure the strip on the door edge. |
| Cylinder total length and halves (e.g. 35/35) | 60 mm euro-profile cylinder supplied with most mortise sets | Exact | Remove the central screw and measure both halves. |
| Key profile | Euro profile on mortise sets; proprietary on many rim and cylindrical locks | — | Compare the key blade profile against a euro profile sample. |
Retrofit architectures that work
- Electronics integrated in the cylinder — The cylinder itself is replaced by a cylinder with the motor, battery and radio inside. The outside keeps a mechanical keyway; the inside is a motorised knob. Nothing else on the door changes.
- Motor replacing the interior handle — The interior lever or knob is replaced by a motor unit that drives the 8 mm spindle directly. The outside keeps the original key cylinder and handle. This is the cleanest fit for mortise locks where the bolt is thrown by the key and the handle only retracts the latch.
- Motor on a rim (surface-mounted) lock — A motor unit is fixed to the surface-mounted rim lock case or to its knob, driving the latch or the deadbolt. Common on UK nightlatches and on Asian surface-mounted deadlocks.
- Full lock replacement on the same footprint — The old lock case is removed and a smart lock with the same footprint takes its place. This is the dominant approach in East and Southeast Asia, where push-pull digital locks replace mortise sets on HDB, condo and apartment doors.
The good news is that the mortise side is genuinely euro profile, so the whole European cylinder ecosystem applies — including integrated-cylinder smart locks. The bad news is that a large share of the installed base is the 69 mm rim nightlatch, where the case geometry varies and the inside control may be a knob rather than a turnable thumb-turn. Design for the rim case survey first; it is the harder half of this market.
Related standards
Questions
Which of the three types is most common on an Indian main door?
The mortise handle set on newer and higher-spec doors, the rim nightlatch on the older installed base. Measure the backset to tell them apart: 50 mm points to mortise, 69 mm to rim.
Can a euro-cylinder smart lock fit an Indian mortise set?
Potentially yes, because the mortise set uses a euro-profile cylinder. Check the cylinder length, whether it has an emergency function, and how far it protrudes past the rose.
Is there a national Indian standard for these locks?
Not confirmed in this catalog. The dimensions recorded here come from manufacturer specifications rather than a published standard, so treat them as market practice and verify by measurement.