How are these locks changed?

[twixx]

Hi, I’ve changed normal Euro cylinders in the past without a hitch.

We’ve a just moved into a new home and I’d like to change the locks out of good practice, however, these locks seem to be different to what I’m used to.

Im guessing they’re just normal Euro cylinders but that I’m missing something that’s preventing their release.

I’ve removed the holding screw... only when I loosen the T25 screw pictured does the cylinder consider moving. But it seems to be held somewhere else.

The doors are SBD if that makes any difference?

Any clues on changing the cylinder?

 

[crank39]

SBD = secure by design

That 'thing' with the allen bolt in is likely to be a collar to protect the end of the barrel from snapping, remove to remove the barrel and replace afterwards

 

[twixx]

Thanks for your reply @crank39

Is collar the correct terminology, im still struggling to remove this and im struggling to find any reference material online

I wondered if this was a bespoke feature of the "secure by design" door... hence why I cannot find anything.

 

[crank39]

The allen bolt will go through the gearbox case for the mechanism and bolt into the the collar on the other side, note it has a tiny grub screw clamping one half of the collar to the cylinder, the other half just slides on and is held with the said allen bolt. Remove the cylinder retaining screw and allen bolt and slide the cylinder out with the collar still attached to it(its attached with the grub you can't get access to while in situ)

 

[twixx]

Thanks for your reply again @crank39 , I had another poke at the weekend, and was able to detach the cylinder. I was initially trying to release the full collar, but on Sunday found the collar splits in half revealing a 30/30mm cylinder!