Another IMS bearing thread

[thom4782]

Jamesp:

To your last two comments...

1 - the differential effect of loading on dual and single row the rates of spallation

2 - two mechanisms at play: a) heat hardened bearing seals leak and allow engine oil to blend with / wash out bearing grease and b) contaminants build up in IMS tube oil because inflow and outflow rates are different and they find their way eventually into the IMSB through the leaking inner bearing seal

[Jamesp]

Originally Posted by thom4782

Jamesp:

To your last two comments...

1 - the differential effect of loading on dual and single row the rates of spallation

2 - two mechanisms at play: a) heat hardened bearing seals leak and allow engine oil to blend with / wash out bearing grease and b) contaminants build up in IMS tube oil because inflow and outflow rates are different and they find their way eventually into the IMSB through the leaking inner bearing seal

Thing 1- Once spall begins in any bearing the rate is not of consequence - spall is the removal of chunks of material, not normal wear. This is a failure mode that feeds on itself and quickly destroys any bearing. Lack of lubrication or overload can both result in spall. I posted a picture of cut bearing apart bearing that had lines in it that looked like it could be the start of spall. Jake commented that bearing was failing, but no tribologist came forward to name the failure mechanism.

Thing 2 - You're on the right track, but there needs to be a motivating force to push oil into the bearing or it would tend to just drip off the bearing seal. Granted it would tend to soak in under its own power, but I wonder what motive force could literally push oil past the seal to fill the IMS tube with oil? It may have something to do with thermodynamics.

[Jake Raby]

Trust that Lake Speed Jr. Is one of the Tribologistvthat has been working with us for years on these studies. He is one of 300 people in the world to hold dual certifications as both an oil analyst and a certified lubrication specialist. He just happens to be the guy that we've worked with to also develop the DT40, DT50 and XP9 oils.

He doesn't have time to step forward on forums and deal with a lot of the challenges of doing so. My days on forums are numbered too.

Lake will be part of a PCA Tech event held at our facility on April 5, 2014 where he will be one of the presenters.

[thom4782]

People can debate the fine points of failure mechanisms all day. Whatever the merits, the arguments must consider the two factors that distinguish single and dual row bearings, namely 1) how loads get distributed within their designs and 2) the 8% versus 1% respective failure rates. Lubrication is common to both designs. While it may explain the failure baseline (1%), it doesn't address the rate differences.