[Rodney]

Thanks for all the good input. The day I am talking about was 2 degrees. It was extreme. Our dryer is new and my compressor was new last summer. We don’t have an aux compressor because I don’t have floor slides, pocket doors, or other such accessories. Before adding the drains, all tanks were drained and cleaned and the system was purged. I think we’re in good shape now. Thanks again for the input.

[Larry & Diane]

Jon, my bus is in the shop as I type this having the air system serviced. I am replacing the dryer with a cannister (spin on type) and putting remote pull drains on all of the air tanks (wet, primary, secondary and aux). Is it problematic to put remote pulls on the wet, primary and secondary tanks?

[Archived]

With an air dryer that is serviced regularly it is unlikely you will need to use the lanyards to purge the tanks very often.

I believe that is a throwback to when trucks did not have dryers and daily draining was important.

I change my air dryer cartridge every 2 years and I drain the water trap downstream from my aux compressor often, daily if in high humidity and I have a lot of aux air use from the aux compressor. But I now drain my tanks at my normal lube and service interval of 5000 miles and I get no moisture from any tank routinely. Over the last 24 years I doubt if the moisture I have drained has amounted to a cupful. Air dryers work.

As a coach ages however it is valuable to pay attention to the air dryer because an aging compressor allows the passage of an oil film which blocks the dessicant from absorbing moisture and then moisture does migrate to the tanks. However if you keep noticing the area around where the dryer purges you will see a build up of oil which is a great clue to tell you to perhaps increase the frequency of dryer cartridge replacement.

The drawback to a lanyard is you lose the ability to see if you actually are getting moisture in the tanks, something I can see because I am standing right next to the tank drain when I turn the petcock. For tank purging to work it is necessary to let the tank pressure go to zero. It is also highly beneficial when draining tanks to use that as the opportunity to verify the protection valves are working. That can be done with the lanyards as well as with petcocks.

[Dean]

HOO boy, now Im thinking that the pneumatic system would have been a good subject for the upcoming seminars. Maybe I could sneak in a few questions there

[Archived]

The pneumatic system is a complex topic. The post I made above is a pretty complete description of how we should maintain the system. It’s not magic but does require the owner to insure that the dryer element is changed as necessary, and that the air tanks are drained, not only to verify there is no collected moisture, but that the protection valves are working. Water in the pneumatic system is a huge issue with far reaching consequences so maintenance pays dividends.

Our pneumatic systems include brakes and then everything else. We don’t need to learn about relay valves or protection valves and how and why they work. We just need to know how to do a DOT pre-trip brake check. If we do the proper air system maintenance we already confirmed the protection valves are working.

The everything else in our pneumatic system includes the suspension and again we don’t need to understand the schematics, but we do need to recognize when we have leaks or when something is not functioning, and what our options are. The most reported issue is system air leaks and there is no simple answer. Chasing leaks is as much fun as paying taxes and while there are some shortcuts, everyone who has chased leaks will tell you that it takes patience and a systematic approach plus a bunch of soapy water.

We can get into boring detail on the pneumatic system including how to polish slack adjusters, but few of us need the details as much as we need to be able to recognize we have an issue, and how to best deal with it.