Power tube spacers - How do they work?

[caylegeorge]

Can someone explain what the power tube spacers do?

Is it normal for the spacer in the power tube on a classic valve to be a bit "loose" and slightly free floating inside the power tube when everything is put together?

I recently re-built a valve, and I can hear the spacer rattle around slightly in the power tube when I shake the valve. Its clear when I tighten the power tube tip there is no resistance from the spacer and that it has some wiggle room between the power tube tip and the o ring.

Is that normal?

Even the longest spacer still rattles.

I'm a bit confused as I thought the point was for the different sized spacers to apply more or less pressure on the power tube o-ring.


Thanks for any insight

[Alexndl]

Any pictures of your different parts?

It should not rattle. Do you have the spring version or the spacer?

[caylegeorge]

Yeah so nothing is out of the ordinary from the exploded view you posted.

I have 2 mags here, and both seem to be the same -

Power tube consists of - Power tube tip has an o-ring on it, then there is the metal spacer in there, then there is the power tube o-ring.

^ But, when fully screwed in, the power tube tip is not putting any tension on the spacer. The spacer is just rattling between the tip and O-ring. O-rings are fresh direct from AGD.

[alpha_q_up]

I belive the spacer is there to prevent the oring from being shot out and it comes in different sizes so you can adjust where the oring sits on your bolt stem, this next part was stolen from athomas on AO

"The shorter spacer allows the oring to sit tightly against the back of the bolt while it is back but not cocked. If the spacer is too long, the oring doesn't come forward enough to seal against the back of the bolt.

[caylegeorge]

Good stuff - found this, and it seems to parrot that and also indicated that the power tube o-ring does indeed "float" and is not compressed. Interesting, and useful !

https://www.automags.org/forums/archive/index.php/t-235430.html