To provide secure locking of swinging cell doors, under conventional key control where automatic deadlocking is a requirement.


The lock can be either flush (4L55) or surface (4L56) mounted and is of robust construction based on the Chubb Lock Custodial Services standard cell lock footprint. The main bolt is automatically extended providing a throw of 32mm and deadlocked on closure of door.

Secure locking is achieved as follows:

Unlocking is achieved by a partial turn of the key which lifts the internal blocking mechanism enabling the withdrawal of the main bolt by the handle. The bolt is then retained automatically when fully retracted and door is out of frame.

Locking is achieved automatically; on closure of the door the brass snib bolt is depressed on contact with the strike plate mounted to the frame this then releases the main bolt. Deadlocking occurs when the main bolt is fully extended allowing the internal blocking mechanism to engage.

The lock has an external visual indicator mechanism, which enables staff to verify the status of the lock. When the indicator is horizontal the lock is secure any other state is insecure.


Solid Case Technology; Lock case machined from single piece carbon steel.
Steel main bolt, with carbide and anti-cutting rollers and 32mm throw.
Brass quick acting stud release mechanism.
External visual locking status indication.
Independent 7-lever locking mechanism.
Factory restricted key section.
5 bolt secure fixing.
Integral baffle arrangements to resist interference via the keyhole.
Escutcheon designed to give positive key alignment.


Mechanical locking mechanism tested to a minimum of 100,000 operations.
Handle mechanism tested to a minimum of 100,000 bolt operations.
Stud release mechanism tested to a minimum of 100,000 operations.
Saw attack 12 hours
End load 25 KN.

Additional Features

Range of Anti-Ligature furniture options available.
Range of fixings including backplates, stud fixings, locking plate and keeps.
Available in alternative paint / furniture finishes on request.
External handle designed to shear under excessive load to prevent damage to internal lock mechanism.
Interchangeable mechanical inner locking unit to enable re-coding.

Materials and finishes

Lock case - carbon steel electro-plated and powder coated exterior.
Main bolt - carbon steel electro-plated.
Main bolt follower - high tensile brass.
Keys – Hardened Steel.
Levers and springs – Brass / phosphor Bronze.  

Dimensions and Weights

Case Height 286mm
Case Length 267mm
Case Thickness 29mm
Bolt Throw 32mm
Bolt Depth 45mm
Bolt Thickness 22mm

Weight (lock only) 4L55 10.5Kg
Weight (lock only) 4L56 12.4Kg

Total Range

The lock is available in left or right hand variants for opening in or opening out doors and can be fitted to steel or wooden doors. A range of backplate stud lengths is available to suit door thicknesses from 25 to 70mm.

Fully dimensioned customer drawings are available on request to assist with door preparation.