3G112 Mark 2 - Morticed Deadlock – Double Action


To provide secure deadlocking of swinging doors or gates where an enhanced level of security is necessary. This lock is specifically designed for very high use applications; typically securing perimeter doors and main access routes.

The 3G112 Mark 2 is a mortice deadlock of robust construction based on the Chubb Locks Custodial Services small mortice footprint. The mechanical deadbolt provides an overall throw of 34mm which comprises an initial throw of 17mm and a second throw of a further 17mm.

The lock provides two independent bolt throws where each throw is operated by a unique key. The keys are designed so that neither key will perform the function of the other key.

The lock is operable from both sides with separate key holes for each key type. The escutcheon is designed to prevent the wrong key being inserted into the lock.

Secure locking is achieved by two independent keys:

Singles Key - Operates first throw only

  • Locking is achieved by inserting the singles key into the dished keyhole and rotating fully, this action will extend the bolt to its first position.
  • Unlocking is achieved by inserting the singles key into the dished keyhole and rotating fully, this action will withdraw the bolt.

Note the Singles key will not operate the second (Doubles) throw.

Doubles Key - Operates second throw only

  • Locking, providing the singles key has been used to operate the first throw, the doubles key can be utilised. By inserting the doubles key into the offset keyhole and rotating fully the bolt will be thrown to its maximum extent and preventing operation by the servant key.
  • Unlocking is achieved by inserting the doubles key into the offset keyhole and rotating fully, this action will withdraw the bolt to enable operation under servant key.

Note the Doubles key will not operate the first (Single) throw.



  • Composite deadbolt, with carbide anti-cutting rollers and 34mm throw.
  • 16 lever highly durable mechanism.
  • Independent single and double actions.
  • Low friction key journals.
  • Lever arrangement designed to provide extended product life.
  • Dedicated key profiles.
  • Escutcheon designed to give positive key alignment.
  • Security fixings to prevent unauthorised removal.


  • Lock tested to a minimum of 500,000 key operations.
  • Saw attack 12 hours
  • End load 13.5kN
  • Side Load 13.5 kN

Additional Features

  • Suitable for external and internal use.
  • Range of fixings including reinforcing plates and locking plates.
  • Available in alternative furniture finishes on request.
  • Can be keyed with 3M56 Mark 2 Hook Bolt
  • Gate boxes for steel door applications recommended.
  • Escutcheon trim plates supplied for wooden door variants as standard.
  • Rebate kit available for wooden door applications
  • Monitored versions available with micro-switch sensing of bolt position.
  • Single sided version available on request.
  • Singles key action only, version available on request. 

Total Range

  • The lock is not handed, however for use on steel doors the short forend version should be ordered and for wooden doors the long forend version is recommended.
  • NOTE: Wooden Doors: This lock should be fitted to a wooden door with a minimum thickness of 54mm. Please contact CLCS for guidance if alternative wooden door thicknesses are required.
  • Fully dimensioned customer drawings are available on request to assist with door preparation.

Dimensions & Weights

Lockcase depth (total)171.5mm
Lockcase height114mm
Lockcase width21mm
Weight (lock only)2.1kg



  • Lock case - carbon steel electro-plated.
  • Bolt - stainless steel and brass composite.
  • Escutcheons - silica brass
  • Keys - hardened steel
  • Levers and springs - brass / phosphor bronze.