tandem trailer wheel bearing - different grease methods on each axle

I just bought a 2007 Eclipse Attitude toy hauler. In advance of our first adventure, I went through the brakes and wheels bearing this weekend. My question is regarding the wheels bearings grease fittings. I removed and repacked the bearings with fresh grease after inspecting the bearings. I noticed that the forward and rear axles differ. The forward axle did not have a zerk fitting although there is a threaded hole on the end of the axle which I assume will accept a zerk. If the zerk fitting was there, the grease would be fed to the outside bearing. Conversely, the rear axle does have a zerk fitting at the end of the the axle with the grease being fed to the inner bearing. First question is: why the difference between axles? Secondly, should I put a zerk fitting on the forward axle and give a periodic pump or two from the grease gun?

Thanks in advance!

They only guess I could make it that one of the axles has been replaced at some point, resulting in a different model.  Sounds like one has the Dexter EZ Lube system and the other not. I doubt if the factory made it that way, though RV mfgrs have been known to do some strange things in the name of expediency.

Gary,

Thanks for the reply and axle identification. I was unaware of how the EZ axle was designed to work. It seems like a nice concept; just pump new grease into the zerk for fresh grease to the bearing. I will however continue to repack the bearings the old fashioned way annually so I can inspect the brakes as well. I am grateful for the knowledge you shared.

I have no idea about why the two different axles...other than to agree with Gary's answer as a very logical idea.

As a former industrial maintenance engineer, I used to spend a lot of time with rotating machinery and troubleshooting bearings of all sorts....some bearings with balls roughly the size of a softball.  Personally, I'm not a fan of zerks on any greased high speed bearing system.  It think it tends to overload the whole works with too much grease, increasing heat retention.  Bearing need really very little grease "IN" them.  The rest of that void in there really should be open.  IMHO, I think you are on the right track to continue doing it the old fashioned way.  My only exception to that approach might be with boat trailers where the hot bearings that really aren't sealed all that well get submerged.... that's where the zerk might make some sense in my opinion....

blw2 said:

I have no idea about why the two different axles...other than to agree with Gary's answer as a very logical idea.

As a former industrial maintenance engineer, I used to spend a lot of time with rotating machinery and troubleshooting bearings of all sorts....some bearings with balls roughly the size of a softball.  Personally, I'm not a fan of zerks on any greased high speed bearing system.  It think it tends to overload the whole works with too much grease, increasing heat retention.  Bearing need really very little grease "IN" them.  The rest of that void in there really should be open.  IMHO, I think you are on the right track to continue doing it the old fashioned way.  My only exception to that approach might be with boat trailers where the hot bearings that really aren't sealed all that well get submerged.... that's where the zerk might make some sense in my opinion....

Click to expand...

I'm not an engineer, but have fought with some management over that very thing. Overgreasing bearings. When we finally had a temperature monitoring system installed, I could show them in real time what overgreasing a bearing can do. And these are not high speed bearings, all are less than 200 rpm's. They won't go for an ultrasonic system, which in my opinion is the best way to monitor bearings.

yeah, that job I had was primarily doing predictive maintenance work.  Primarily doing vibration analysis before vibration analysis became mainstream.  I understand that later, the vibration job fell more to lubrication mechanics, then ultimately to online automatic DCS stuff...Now days I suppose it's all permanently installed sensors connected through a DCS.

Vibration was our primary tool, we checked almost every rotating bearing in a very large integrated pulp and paper mill, most monthly.  We also had ultrasonic tools, IR tools, oversaw oil and lube analysis, oversaw NDT work on the tanks and pressure vessels, alignment, and all sorts of other detective work.  We didn't do much with stuff running as slow as you though.

We used ultrasonic primarily for air leaks but it was a good tool for basic bearing monitoring and such.  Better than a broom handle against a cheek bone for sure! 

The folks doing it just maybe 2-5 years before me were on the forefront, using oscilloscopes.  We had portable spectrum analyzers.  It was fun and I learned a ton.  We could spot a pending bearing failure in some cases well more than a year prior.  We'd monitor it, then when it was time, suggest that the maintenance folks change the bearing.  We often got the old bearings and other machinery to cut open and confirm.  We could tell if it was an inner race failure, a cage failure, outer race, or roller....just by the vibration.  We could also spots lots of other problems.... alignment, looseness, and even problems with electric motor drives (SCR's) by measuring vibration at the motor.  Once in a while we would be wrong...but that was very very  rare.  It's an amazing tool really.

blw2, you win the AA (abbreviation award).  Perhaps that was a private conversation with kdbgoat, but others may be interested in understanding it.

On the original topic:  I just had an axle replaced for reasons unrelated to the bearings.  The head mechanic advised not to push grease into the bearings, as it may blow out the seal and get on the brakes.  I believe I've read the same advice on RVforum before.

DCS-distributed control system

IR-infra red

NDT- non destructive testing

SCR- silicon controlled rectifier

Sorry about that..... I was reminiscing I guess and kinda got off track.....

It's ok, I got it all. I spent some time installing vibration monitors into a DCS.

Thread drift!....



I had a dog once.... ;D