Three unlocks and three-stage locks

Structure, usage, modification, installation dimensions | Hong Kong old public housing/stainless steel door only

Origin of the name Three-segment structure

Three unlocksis named after its internal structure is divided intoThree paragraphs: One-stage inclined stroke + two-stage square bolt. Three stages operate independently, providing double security protection of "automatic locking + manual strengthening".

Common installation locations

Hong Kong old-style public housing wooden doors, stainless steel doors, metal gates, gates, etc. Because of its ruggedness and reliability, it is still widely used today.

Slant + both sides of the latch Automatically lock

The inclined tongue is responsible for closing the door and automatically locking it; the two sections of the square latch can be extended with a key or indoor twister to provide additional anti-theft strength. The three sections are independent and do not interfere with each other.

Installation dimensions

Lock center: 60mm (distance from the center of the lock cylinder to the edge of the lock body)
Lock hole: 32mm (door side opening diameter)
Applicable to most standard old door reserved holes.

Outdoor usage (outdoor operation)

Lock the door when going out

1. Close the door → Slope automatically locks (first paragraph)
2. For more security, use the key to turn the key clockwise.Twice → Extend two sections of square bolt (second and third sections)

Open the door when entering the house

Method 1 (fully unlocked)：Key screwTwice → Retract the two square bolts one after another; then tightenThe third time → Retract the slope and open the door.
Method 2 (quickly open the door): Tighten directly → Only retract the diagonal lever (assuming the square bolt is not extended), and then the door can be pushed.
The actual situation depends on whether the square latch is locked. If it only relies on the automatic lock with a tilt, the door can be opened by twisting it.

Indoor usage (indoor operation)

Stay / Ordinary lock door

Close the door → Slope automatically locks (same as outdoor)
For extra safety, place indoorwrist handsScrewTwice → Extend the two sections of the square latch and lock it completely.
※ Twisting the hand can only control the square latch, while the tilting lever remains in the automatic state.

Leave indoors

First place the indoorTwist twice → Retract the two-stage square latch
againHold hands → Retract the slope and open the door at the same time
The whole process is fast and smooth, and no keys are required.

Modification type	Interior design	Advantages/applicable scenarios
Standard three unlocking	Indoor knob (knob) control square latch	Simple and direct, suitable for quick locking of wooden doors and indoor doors.
Modification: indoor lock cylinder	The indoor twister is changed to a lock cylinder, and a key is required to control the square latch.	Key benefits: When fitted to a metal gate, it prevents an intruder from hooking the deadbolt through the gate gap with a coat hanger or metal rod, greatly improving security.

Illustration of outdoor entry process

Lock status	Unlocking action	Unlocking results
Only the latch is automatically locked (deadbolt not locked)	Turn the key	Retract the slope and open the door directly
Slant + a section of square latch is locked	Turn the key twice to retract the deadbolt, then a third time to retract the latch	Fully unlocked and can open the door
Slant + two-stage square latch full lock	Turn the key twice to retract both deadbolt stages, then once more to retract the latch (three turns in total)	Complete door opening process

Comparison of indoor twisting hands

Stay/Normal Lock: close the door to lock the latch automatically; turn the thumbturnTwice → the deadbolt extends fully for greater security.
Leave the room: Twist your handsTwiceto retract the deadbolt → pull the handle once to retract the latch → open the door.
Emergency: if only the latch is locked, pull the handle directly to open the door; the thumbturn is not required.

Safety reminder: If the metal gate uses a standard three-way lock (indoor twist handle), a thief may use an iron wire to hook the twist handle from the gate slit to open the lock. It is recommended that the metal gate be replaced with a "modified indoor lock cylinder" three-opening lock, which must be opened with a key first to eliminate the risk of unlocking the hanger.

Installation dimensions and precautions

Standard size:

Backset:60mm
Lock hole diameter:32mm
Applicable door thickness: 35mm – 50mm (common wooden doors/stainless steel doors)

Replacement tips:

Before replacing the three-opening lock, please confirm whether the distance between the locks is 60mm, otherwise you need to re-drill the hole.
If the original lock system is the old-style "gourd gallbladder", most of the three-opening locks are compatible.
It is recommended to hire a professional locksmith to install it, ensuring that the angled and square bolts are aligned with the door frame.

FAQ	Answer
Will the three-way lock automatically lock when closing the door?	Yes, the tilt tongue has an automatic pop-up function and locks when the door is closed. Square latches require manual locking with a key or indoor twister.
Why do you sometimes open the door just by turning the key outside?	Because you only relied on the oblique automatic lock before, and did not lock the upper latch. Just twist and retract the slope to open the door.
How does Tie Run use three locks to prevent "clothes hanger unlocking"?	Choose the "modified indoor lock cylinder" version. You need to use the key to open the indoor lock first, and it cannot be opened with a wire from the outside.
What is the difference between a three-way lock and an ordinary door lock?	General door locks usually only have an oblique angle + one section of square bolt; a three-opening lock has two sections of square bolt, which has stronger anti-theft power and clear structure.

101 Lock Picking・Three Lock Picking Experts

We deal with a large number of three-opening lock installations, repairs, modifications and upgrades every day. Whether you want to change the locks of an old public housing estate, want to prevent the metal gate from being hooked, or don't know how to use indoor twisters correctly, the 101 locksmith team can provide professional advice and services.Quotation first and then construction, no hidden charges。