How to Operate and Change the Combination on the Chubb Manifoil MK4 Combination Lock

The Chubb Manifoil MK4 is a high-security combination lock is used by Australian Government departments to secure Class A and Class B containers and cabinets. It’s a trusted solution for securing sensitive materials — and understanding how to correctly operate and maintain it is essential. This lock features a four-number combination. The first three numbers are changeable by the user, while the fourth number is fixed and cannot be changed.

How To Open a Chubb Manifoil MK4 Lock- To open, use the following dialing sequence:

1. Turn the dial five times clockwise > (R) to the first number
2. Turn the dial four times anti-clockwise < (L) to the second number
3. Turn the dial three times clockwise > (R) to the third number
4. Turn the dial two times anti-clockwise < (L) to the fourth fixed number (fixed – see below)
5. Turn the dial clockwise > (R) one final turn until the dial comes to a stop and the lock opens

⚠️ Important: If you overshoot any number while dialing, you must restart the entire sequence from the beginning. You cannot reverse the dial to correct a mistake.

Understanding the Fixed Fourth Number – This fixed number depends on how the lock is mounted to the safe or container. The fourth digit is not changeable and will always be one of the following:

• 0 – for left-hand (L/H) mounting
• 25 – for bolt-down mounting
• 75 – for bolt-up mounting

How to Lock the Manifoil MK4 – To secure the container or cabinet turn the dial at least five full turns anti-clockwise (L)

Changing the Combination

You can change the first three numbers of the combination using the change key. Before You Begin:

• Ensure the container or drawer is open
• Ensure the lock is in the OPEN position
• Have the current combination ready
• Do not close the door until you’ve successfully tested the new combination multiple times

Step-by-Step Instructions:

1. Dial the current combination, stopping at the 11 o’clock mark (not 12 o’clock) — follow steps 1 to 3 above, excluding the fourth number and final turn
2. Insert the change key into the rear of the lock and turn 90° anti-clockwise (L) until it clicks
3. Leave the key in place
4. Dial the new combination to the 11 o’clock position (again, steps 1 to 3 only)
5. Turn the change key in the rear of lock 90° clockwise (R) to re-lock and remove the key
6. Test the new combination several times with the door open — using the full opening sequence (ending at 12 o’clock)

• If fourth number is 0: avoid 95–10 for the third number
• If fourth number is 25: avoid 20–35 for the third number
• If fourth number is 75: avoid 70–85 for the third number

Common Factory Settings – For First Use

• 40 – 50 – 60 – XX
• 50 – 25 – 50 – XX (XX represents the fixed fourth number)

Expert Help Available

Our team includes SCEC-Endorsed Locksmiths experienced with the Chubb Manifoil MK4 and other high-security locking systems used by government agencies and defence contractors.

📞 Call 1300 500 600 to speak with our Sales Team
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