Bearings !

A special section just for steam engines and boilers, as without these you may as well fit a sail.
Post Reply
hedleypiper
Just Starting Out
Just Starting Out
Posts: 10
Joined: Tue Jul 18, 2017 1:17 pm
Boat Name: justine elizabeth

Bearings !

Post by hedleypiper » Thu Apr 16, 2020 1:07 pm

Just how tolerant are our big ends? The HP little end overheated last season and there was a dry squeak from the HP area. Opened the little end, black crud burnt on the shells and spindle. Very delicate scrape and polished of surfaces by hand. Seemed smooth, solid and free turning.
Big end only contact on about 50% of the surfaces. Slightly more energetic scrape of the shells and cutting of oil channel across surface. Now free turning but very slight side to side movement(you can just see the oil meniscus deform, no room for a feeler gauge). In the light of the CV lock down, do I just put the engine back and "suck it and see" ? It is just such a fag getting it in and out and re aligned.
At least the bilge is clean !
Mike Rometer
Full Steam Ahead
Full Steam Ahead
Posts: 833
Joined: Sat Aug 13, 2011 6:41 pm
Boat Name: B.N.Y.S.
Location: Middle Earth

Re: Bearings !

Post by Mike Rometer » Thu Apr 16, 2020 2:12 pm

I take it you mean "end float"? It is of no matter, and better that there is some. As long as the shells are gripped in the rod and the clearance is minimal it'll be fine.
Retirement is about doing what floats your boat!

A BODGE : - A Bit Of Damn Good Engineering.
User avatar
Lopez Mike
Full Steam Ahead
Full Steam Ahead
Posts: 1803
Joined: Wed Dec 07, 2011 6:41 am
Boat Name: S.L. Folly
Location: Lopez Island, Washington State, USA

Re: Bearings !

Post by Lopez Mike » Thu Apr 16, 2020 7:16 pm

Might check the clearance with some Plastigauge. Dirt cheap.

https://www.plastigaugeusa.com/how.html
If you think you are too small to make a difference, try sleeping with a mosquito.
Dalai Lama
User avatar
fredrosse
Full Steam Ahead
Full Steam Ahead
Posts: 1723
Joined: Fri Nov 20, 2009 5:34 am
Boat Name: Margaret S.
Location: Phila PA USA

Re: Bearings !

Post by fredrosse » Sat Apr 18, 2020 4:39 am

Moly lube oils can take far more pressure than conventional oils without this additive.
User avatar
barts
Full Steam Ahead
Full Steam Ahead
Posts: 899
Joined: Wed Nov 18, 2009 6:08 am
Boat Name: Otter, Rainbow
Location: Menlo Park, CA
Contact:

Re: Bearings !

Post by barts » Sat Apr 18, 2020 5:07 am

You might take a look at PV values for your bearings; so long as you're within the safe values for the bearing materials and the supply of oil is adequate, these will likely be ok. Extra clearance causes noise pretty quickly, of course. The little ends are tricky, with very little motion to set up an oil film; here's where moly can save the day. There's often not a lot of extra space in some of the cross head designs, either.

- Bart
-------
Bart Smaalders http://smaalders.net/barts Menlo Park, CA
Post Reply