How should I model a floating bush 2

[RylEnfield]

Hello there
the flywheel crank pin of my single cylinder engine, has a floating plain bush ie there is a solid bronze bush between the crank pin and conrod ....not in babit type as per car, modern bike...
But a large lump of bronze like a polo mint ( would be easier to draw a picture .....)

My question is ...can I model the crank pin , floating plain bush as an ordinry plain bearing or are there any conciderations I may have to account for due to the reciprocal nature of the conrod

Kind regards in advance

Stephen

 

[magnograil]

Hi Stephan,
The bearing material does not matter, only the configuration. Books on journal bearings give various equations for full and half Sommerfeld films, easiest to get a copy of the Machinery Handbook and look up journal bearings. They have equations and examples. The oscillating rod load only effects where the minimum film thickness is located. I wrote the equations in Excel to solve for the oil temperature rise, minimum thickness and flow requirements.
Is this a Bullet 500? I have a '56 Tomahawk.

 

[RylEnfield]

yes it is a 500 bullet !! but my councillor said I would get over this Phase ....The wife has given up ...and I havent seen the dog for a few days ...

Thanks for your reply ...it was the oscilating load and the crank position i was worried about, I modeled those rocker block to find out how much oil they required and which pump to use.. Then we looked at making new rocker blocks as you know they wear ...
I figure the wear is due to insuficient oil flow ...hence the reason to find out how much the floating bush requires the oil presure at running temp is as low as 6 psi ..
I have Machineries and will look ..My main concern was I know a rotating bearing pmps the oil wedge around ...but I wasnt sure if the crank pin did the same ...if it does I ll feel more confident in my aproach .

Finally I to seem to prefer the somerfield number ... bit old fashioned way now ..but so is the pencil I use !!!

kind Regards
Hope to see you on other Enfield Chat sites

Stephen

 

[GregLocock]

http://www.royal-enfield.net/articles/wilson-jones_bullet_article.doc

In the light of a comment made in that document I'd be inclined to treat it as a normal plain bearing, and work out the bearing loads and speeds as if it were fused to the crank, and then repeat with it fused to the con rod.

You may find something relevant on the NACA website,

http://naca.larc.nasa.gov/

as floating bushes were very popular in radial engines.

I couldn't using the simple search.





Cheers

Greg Locock