3G112 Mark 3 - Morticed Deadlock – Single Action



To provide secure locking of swinging pass / control doors and gates where positive locking by a mechanical key is required.


The 3G112 Mark 3 is a mortice deadlock of robust construction based on the Chubb Locks Custodial Services small mortice lock footprint. The mechanical deadbolt provides a throw of 17mm.

The lock provides deadlocking operated by a unique key profile to the Mark 3 range of locks and will not operate Mark 1 or Mark 2 lock variants. The lock is operable from both sides and the escutcheon is designed to allow only the correct key profile to be inserted into the lock.

Note: This lock cannot be master keyed.


Principal of Operation

  • To Deadlock - Insert the key in to the escutcheon and rotate once (top of the key rotates towards the door edge)
  • To Unlock - Insert the key in to the escutcheon and rotate once (top of the key rotates away from the door edge)

Standard Features

  • Heavy Duty Electroplated Steel cap and case
  • 17mm throw laminated bolt fitted with anti-saw Tungsten Carbide rollers
  • 12 lever key mechanism (6 for the purpose of differing)
  • Factory restricted hardened steel one piece key
  • Nylon key journals moulded to the cap and case to increase wear resistance
  • Security fixing screws
  • Microswitch versions feature bolt status monitoring


  • Mechanical locking mechanism tested to a minimum of 500,000 operations
  • Saw attack on the main bolt 12 hours
  • End load 13.5 kN
  • Side Load 13.5 kN
  • Impact tested to UK Government requirements

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.

Dimensions & Weights (Approx)

Case Height114mm
Case Length171mm
Case Thickness21mm
Bolt Throw17.4mm
Bolt Depth58.7mm
Bolt Thickness16.5mm
Weight (lock only)2.5kg



  • Lock case - carbon steel electro-plated
  • Main bolt - stainless steel bolt tail with brass bolt heads and running blocks. Stainless Steel bolt head & blocks are available
  • Escutcheons - investment cast brass natural
  • Faceplate - Brass
  • Keys - Hardened Steel
  • Levers and springs - Brass / phosphor Bronze.