What does the adjustment of these do?

[silverfox2019]

I'm adjusting my UPVC door. The (flag) hinge adjustments were logical and worked easily.

But at the side of the door, there are some knobs (highlighted on the attached) that rise up as part of the multi-point locking mechanism when the door handle is operated. Presumably that's to hold the door closed properly in the latch places.

The knobs have a hexagonal inset to allow adjustment using an Allen key. Google suggests these might be called "Latch Keepers" and the adjustment is for "compression".

I had thought maybe turning the knobs anti-clockwise would push the knobs out and further towards the metal vertical part of the frame so the knobs go deeper (or higher or lower instead?)into the latches. But when I try the adjustmnet, I can't actually see anything happening.

What are these things called and what is supposed to happen when one adjusts them, please.

 

[crank39]

They are called roller cams, the outer rolls around like a bearing so when it slides down the latch or keep on the frame you get a nice smooth action and not metal on metal. The cam is rivetted and does not come off, screw in or out, it's mounted concentrically and if you turn it through 360° it will move sideways and up and down, the dash or dot helps you to see which orientation it's in, by having the dash or dot closer to the gasket on the door means you've given it maximum compression, turn it 180° so it's facing away means you have reduced compression, too much compression means you put too much strain on the handle and the mechanism and will result in premature failure, find a happy medium

 

[foxhole]

My cams have a Allen key adjustment, moves them up or down about 2mm.

 

[crank39]

My cams have a Allen key adjustment, moves them up or down about 2mm.

And left and right surely

 

[foxhole]

And left and right surely

Yes but only up or down has any use.

 

[crank39]

Really? Sideways increase or reduce compression