chubb mortice locks and parts

[Gary Stephenson]

That writing on the lock was from me 5g for 5 gauge and 110 for the lock, I adapted a 110 and 6 gauge curtain to suit the fortress keys, but never having seen one couldn't figure out how it would work from both sides unless you used a and b section keys, didn't realise that the curtain is profiled to allow entry from both blank profiles unless it is the 3g135 case itself that stops the wrong key profile from entering.
Thanks for putting that picture up Tom.

[Tom Gordon]

That writing on the lock was from me 5g for 5 gauge and 110 for the lock, I adapted a 110 and 6 gauge curtain to suit the fortress keys, but never having seen one couldn't figure out how it would work from both sides unless you used a and b section keys, didn't realise that the curtain is profiled to allow entry from both blank profiles unless it is the 3g135 case itself that stops the wrong key profile from entering.
Thanks for putting that picture up Tom.

The case had a spike that restricted key entry to one hand or the other.
The lock may have been made available for single sided entry though with a different follower

[Gary Stephenson]

Cheers Huw.

[chubbbramah]

If the 'Fortress' was 3G135, what and when was the 3G71? all I know is pre-1962.