Thursday, 5 March 2015

Con-stern-ation*

It goes without saying that Tortoise is a strange boat, and not least in the nether regions. The prop shafts slopes downwards, river-style (there's a bloody great universal joint just to the right of the picture). To the near right there's a plate that the shaft passes through, but serves no useful purpose, as far as I can see, but...

On the left, stuffing box & lock nut. That I understand.

Then - though, the collar with the overlong grub screws (must find some shorter ones), clamps on the shaft. Either side of that, there's a pair of big washers with a ball race in between. I can clamp the collar towards the stuffing box so that the left hand trio have some function, or towards the fixed plate so the other set does - but can;t see a way that both have use. It is possible that the fixed plate it supposed to interact as a sort of bearing, but it can't necessarily support the shaft.

So I'm guessing in the past it has been assembled wrongly, or possibly has bits missing (or even extra, or at least unrequired bits). I'll leave it for now toward the stuffing box as a kind of extra grease water barrier, but all a bit of a mystery.

Blacking soon, so I've the opportunity to at least attempt to replace the stuffing, and try to make sense of the rest of it...

* well, there was no call for a gland pun, was there?

4 comments:

Neil Corbett said...

Is it a thrust bearing transferring prop thrust through that plate?

Simon said...

Well, having done some reading, it certainly should be!

Neil Corbett said...

Having consulted Rick, we reckon that collar should be moved over tight against the thrust bearing.

Simon said...

agreed - having looked at it again the other day, that's what I did, makes a lot more sense, although leaves other ball race set flapping about in the wind.

I guess at one point of stuffing box position that set provides thrust support in the other direction too.

Next challenge is to work out how to get inside to restuff - prop may have to come out entirely, or at least pull back a bit...