Rim lock door knob query

[Gossamer]

Hello,
I've brought a door knob to fit to an old rim lock.
It came without any instructions and I can't work out what the circled components do (see picture). It seems to fit using just the door knobs and spindle. I cant work out what the collar and 2x plastic washers do.
Any ideas?
Cheers.

 

[Gerrydelasel]

The plastic washer is probably meant to go between the knob and the rimlock to prevent scratching the face of the rimlock when twisting the knob. Not sure why they give you two.
The other thing allows you to use the rim knob with a modern mortice knob that has a plain square hole and no set screw. You don't need it in this case.

 

[Gossamer]

The plastic washer is probably meant to go between the knob and the rimlock to prevent scratching the face of the rimlock when twisting the knob. Not sure why they give you two.
The other thing allows you to use the rim knob with a modern mortice knob that has a plain square hole and no set screw. You don't need it in this case.

Cheers. The washers won't fit as the lock side knob (I assume) fits onto the square end.

So what would the collar screw into?

 

[Gerrydelasel]

The washers won't fit as the lock side knob (I assume) fits onto the square end.

But the washer is big enough to fit over the square end, isn't it?

So what would the collar screw into?

If you just had a mortice knob with no set screw or thread then the rim knob would simply pull the spindle out of the mortice knob, and out of the door. The threaded collar prevents this. Presumbly your mortice knob is threaded or has a set screw (?), but if not then it looks like it would be arranged as in the second diagram.

 

[Gossamer]

But the washer is big enough to fit over the square end, isn't it?

No they are too tight to fit over the square end, which much be the rim lock side.

If you just had a mortice knob with no set screw or thread then the rim knob would simply pull the spindle out of the mortice knob, and out of the door. The threaded collar prevents this. Presumbly your mortice knob is threaded or has a set screw (?), but if not then it looks like it would be arranged as in the second diagram.

The lock side knob slides over the square end and has a grub screw. The outside has a knob with cover which screws onto the door and the square threaded side just slots in. There isn't a grub screw, its kept in place by 4 screws into the door and a clip inside.

Thing is, the threaded collar, if screwed into the door would prevent the collar and threaded end of the spindle from turning, so I don't see the point.

 

[Gerrydelasel]

The outside has a knob with cover which screws onto the door and the square threaded side just slots in. There isn't a grub screw, its kept in place by 4 screws into the door and a clip inside.

Then what is to stop you pulling the spindle out of that (mortice) knob from the opposite side of the door? The collar must hence be necessary, per my second diagram, no?

Thing is, the threaded collar, if screwed into the door would prevent the collar and threaded end of the spindle from turning, so I don't see the point.

The spindle can still rotate within the collar (i.e. screw in and out). It only needs to twist a quarter or half turn at most, depending on the latch mechanism.

 

[Gossamer]

Thanks,

Then what is to stop you pulling the spindle out of that (mortice) knob from the opposite side of the door? The collar must hence be necessary, per my second diagram, no?

I think the situation is a hybrid of your diagrams. The one on the left is how the outside of the door is / should be and the right one how the rim lock side is / should be. I think, and will need to check properly, that the spindle can't pull through the rim lock. I needed to push it through from the outside. Maybe a design feature for this very reason.

The spindle can still rotate within the collar (i.e. screw in and out). It only needs to twist a quarter or half turn at most, depending on the latch mechanism.

Seems like a weird design to me!