Crank wear

I've only a vague picture of what's required, but what about Devcon? Metal spraying?

Cheers Tim

Tim Leech Dutton Dry-Dock

Traditional & Modern canal craft repairs

Likewise. Not being an expert on the various lube systems used on Petter M's over the years (mine is 'New Model' with greased ball and roller mains) a little more description would be useful. Do the rings run on floating sleeves rather than direct on crankshaft then?

The oiling rings run over cutouts in the main and are held off the crank by tapered driving rings which are supposed to be a light drive fit on the main bearing diameter. hth Roland

On my spare 12/14 S the system is exactly the same. On that I remember the rings sitting on top of the crank and they just ran in the main bearing cutouts with the friction spinning them. I don't see how they work if the are not sitting in the grove I would have thought the bearing would run very low on oil as when sat on the crank, the crank picks up the oil from the inside of the ring. The main shells should be held in place by a locating dowell in the cover that holds the shell in place and if it is a good fit or over tight/picked up will rotate without the cover on. This all sounds rather odd to me Roland and I am stunned by the amount of ware on the crank from the rings. As an aside the marine sets had extra feeds from the lubricator for the mains as if the boat was rocking the ring oilers could catch and stop turining meaning no oil to the mains. Perhaps this happened in some way but I would expect the bearings and the crank to have run.

Most interesting problem Roland but I am at a bit of a loss as to solving it.

Regards,

John MS

any room for a wider ring? sammmm

OK, I think I see. Not come across separate driver rings before, pick-up rings usually run direct on shaft. I guess the taper encourages the oil in the crankcase direction rather than towards the outboard end of the bearing?

So, driver rings must be tight enough on shaft to be reliably driven by it but not so tight as to prevent shaft being removed from bearing. I reckon Tim is right - metal spraying and regrinding would probably be the 'proper' way to do it, but I bet Devcon, JB Weld etc would do just as good a job. Sounds like new driver rings might be needed though as I guess ID will have worn over size.

Roland,

Can you not turn down the crankshaft to flywheel dia, then turn a sleeve and loctite in place? N Mcburney has used this trick on 2 Wolseleys I know of with stepped shafts.

Regards

Chris Bedo Kent UK.

I'm sorry but I'm a little bit lost as to thie driver rings idea. Could somebody explain it to me?

Thanks in advance.

John

If the damage is that severe then repairing the crankshaft looks like the best long-term solution, as anything else will leave the grooving etc on the shaft surface.

I just had a look at the Ruston 1ZHR arrangement, which is pretty much just the split oiler ring running directly on the crankshaft:

The oiler ring is about 3/16" or less in width but the proportion between diameters may make the driving of a larger ring at low rpm easier than a smaller ring at higher speed, allowing for oil drag etc, which would be significant enough to slow the oiler ring down enough to start it marking the crankshaft surface?

Peter

-- Peter A Forbes Prepair Ltd, Luton, UK snipped-for-privacy@easynet.co.uk

Might it be possible to turn up a thin shelled & hardened steel sleeve to push fit over the worn part of the mainshaft?

It would be larger than the original diameter of course, but the rings could be bored out to suit, thus maintaining the clearance.

Regards,

Kim Siddorn,

Thanks for all the helpful suggestions. Because the main bearing is inboard of the ring I cannot have anything larger outside the main dia. A sleeve is probably the best solution but it would be rather thin walled and at the governer end about 2" long. The crank has already been reground many times and I suspect that the assembler did not register the need to make new rings to fit the smaller dia. Initially I'll try a light skim and make new driving-rings fitted using Loctite. They do also function as oil throwers as Tim suggests. regards Roland

I can't picture your problem but if you need thin walled sleeves, try these.

John