Crankshaft Deflection

[offshoresnipe]

Great post.
Just wanted to thank all of you for your input, keeps my mind firering.
Like your quote JK!

[JK]

Heehee too bad I managed to type it with a typo, but it does put things in perspective, doesn't it?

[Dieseldame]

Guess we'll know you when we see you

DD

[The Dieselduck]

I changed the avatar sizes to a something bigger, let me know if you need more. Also added a new custom field for the profile...

[WartsilaRoadWarrior]

I have to say that abnormal deflection readings can absolutley point to damaged bearing shells. Although thats not the only possible cause as previously mentioned.
J

[JK]

Another new member!
Welcome.

Post Often , it makes the Forum better for the rest when people share their knowledge and experience.

[Dieseldame]

Hey WartsilaRoadWarrior I wonder what issues you have seen arising from abnormal deflection readings?

DD

[Big Pete]

Sorry but I completely disagree with Wartsila Road Warrior. This is a widely held misconception.
I don't want to get into a p....... match, but if anyone can show me an entry in a Modern Makers manual or Text Book that says worn bearings can cause excessive deflections I will eat my proverbial hat and make a donation to the charity of their choice.

Wear or damage to the bearings can not cause deflections.

To cause a deflection a force has to push the crankshaft out of alignement, in a fixed direction relative to the main bearings, so that the direction of the force on the crankshaft is changing as it turns. How can excessive bearing clearance cause this force?
Modern crankshafts are short & stiff to resist the firing loads, they will not deflect under their own weight.
See my explanation way back in my 2nd post on this topic.

Even if you removed the shells from one main bearing entirely, then took a set of deflections, I doubt if you would see a significant change in the deflections. ( Unless the shells removed were adjacent to the cam shaft drive chain or flywheel.)

If the bearings are sufficiently out of line to give excessive deflections that would cause damage to the bearings, or the bearing damage could be coincidental.
Excessive tension in the cam shaft drive chain could also give high deflections and cause bearing damage, but in this case I would expect problems with the cam shaft bearings as well and excessive wear on the chain.

Big Pete