Stuck on side of road - outside Bolivar, TN (Air system problem)

[eagle19952]

Straight trucks and some tractors use an Inversion Valve which does not function during normal operation of the vehicle's brake system but operates in the event of a primary (rear service brake) system failure. When the Inversion Valve senses an imbalance of the primary and secondary delivery pressure during an application of the foot valve, it inverts that pressure to release air from the spring brake chambers. This permits the modulated application of the mechanical spring brake chambers on the rear axle(s) to assist the front brakes in stopping the vehicle safely.

[eagle19952]

If you have any questions or need additional
assistance, contact the ArvinMeritor Customer Service Center
at 800-535-5560......

[technomadia]

Hmm how about that! Wasn't far off about an open air line after all!
You can block me here too if you'd like!
Good luck in the future!


Sent from my iPhone using Tapatalk

First of all... not sure I understand the blocking comment - to the best of my knowledge, we have no reason to block you anywhere? 

And yup, those who identified an open air line get the diagnosis score on this one. Glad we kept that balanced with the other alternatives, and didn't start disassembling things quite yet until we got some air in the system and did some further troubleshooting.  Many thanks to all!

-Cherie

[technomadia]

Straight trucks and some tractors use an Inversion Valve which does not function during normal operation of the vehicle's brake system but operates in the event of a primary (rear service brake) system failure. When the Inversion Valve senses an imbalance of the primary and secondary delivery pressure during an application of the foot valve, it inverts that pressure to release air from the spring brake chambers. This permits the modulated application of the mechanical spring brake chambers on the rear axle(s) to assist the front brakes in stopping the vehicle safely.

Thank you much for the further information.. very appreciated.  Also got some tips on the BNO FB page that we can bypass this if needed to get to a safe location.

On the hunt in the morning for a TR-3 locally.. and good to know we have other options if we can't source one tomorrow.

Thanks again all for the help and support

[eagle19952]

From Bendix
*ReMan pn*..*New pn#*
*101450RX* *101450N*
*Special-Duty Bus Application

Cross References: 280758, 245407, 280758X, 280773, 6D1039, 3902813, 86883026, 36Z1406, 664638C91, 745280758, 6966570, 3902813, 4L293, 664638C91, 90011749, 4111, S-C341, SD281, 3902813, 8084521, G3902813
A cross reference listing means that this valve is a suitable replacement for the part numbers listed. Some changes in air line plumbing may be required.

For instance, if you google 6D1039+valve, you will find that # is Caterpillar's part number for the Bendix TR-3
664638C91...from experience I can tell you at a glance this is Navistar/International Harvester's # for your part.

PS Your welcome.....even tho I am blocked and ignored...
Good Luck

[technomadia]

From Bendix
*ReMan pn*..*New pn#*
*101450RX* *101450N*
*Special-Duty Bus Application

Cross References: 280758, 245407, 280758X, 280773, 6D1039, 3902813, 86883026, 36Z1406, 664638C91, 745280758, 6966570, 3902813, 4L293, 664638C91, 90011749, 4111, S-C341, SD281, 3902813, 8084521, G3902813
A cross reference listing means that this valve is a suitable replacement for the part numbers listed. Some changes in air line plumbing may be required.

For instance, if you google 6D1039+valve, you will find that # is Caterpillar's part number for the Bendix TR-3

PS Your welcome.....even tho I am blocked and ignored...
Good Luck

Thanks... the part number of the valve that came off is 280758, which is not a special bus application one. Seems the difference is the PSI cut on and cut off points?

(and.. have never blocked you here, and definitely not ignoring you here)

[eagle19952]

Seems the difference is the PSI cut on and cut off points?
Hence the Phone #.
I wonder if the valve leak is not a function problem......related to something upstream....
Not being critical here or judgmental.
But often new problems are related to recent repairs, and I almost always try to eliminate those possibilities first. JMW

[luvrbus]

 35 or 70 lbs will both work for their setup

[technomadia]

Seems the difference is the PSI cut on and cut off points?
Hence the Phone #.
I wonder if the valve leak is not a function problem......related to something upstream....
Not being critical here or judgmental.
But often new problems are related to recent repairs, and I almost always try to eliminate those possibilities first. JMW

Yup... agreed. Especially considering a rebuilt compressor just installed on Monday, and the addition of the air dryer.

We have sourced the part here locally, and it is inbound within the hour. And Coachnet just deployed out the mechanic again to assist (at their suggestion, not our ask.. really impressed with their service). Will hook up the new valve, and see where we are from there. Good to have other eyes and experience and tools onsite.

Best working hypothesis is that the new compressor perhaps uncovered a weak link the system? If there are other theories or possibilities, always happy to hear them.

[gumpy]

The new compressor probably had nothing to do with it. Compressors do the same thing whether they are new or old. They compress air. The governor regulates the pressure at which they stop compressing air. The only difference between a new compressor and an old compressor is how long it runs before the governor unloads it. You had the same pressure with the old compressor that you have with the new one.

My guess is it vibrated loose over time and was not caught during maintenance inspections. Fitting might have been cross threaded when installed or the last time it was worked on.  

I think the bigger question might be why was it "dangling". Isn't it supposed to be bolted to something?  Aren't those two holes for bolts? Where are they?
Bolts just don't unscrew themselves simultaneously.

To me, this seems to point to lack of maintenance and/or inspections. I would imagine it's been dangling for the air lines for a long time, and the vibration strained the threads of the fittings.

[luvrbus]

You  got Craig I never saw one installed like theirs the correct way is mount it vertical with the bolt holes furnished with flex lines going to all 3 ports.
The paper label was still in place and readable I would venture to say that TR-3 is not very old vibration done it in

[eagle19952]

Best working hypothesis is that the new compressor perhaps uncovered a weak link the system? If there are other theories or possibilities, always happy to hear them.

Well since you asked....the valve is designed (per the statement above sourced from Meritor) to allow limited use of the front brakes to safely stop the vehicle in the event of rear brake loss or failure....So I would want to know if that was what initiated my problem before I was confident in the repair/replacement of the TR-3 as the "solution".

[eagle19952]

PS. I have seen instances where the valve was not properly anchored because the air lines were shortened because they were re-used as a temporary repair due to a leaky hose.....that never got fixed properly....I usually fired those kind of fixers....And I have seen instances where the lines were to short to begin with and were yanked out by the suspension....causing  what appeared to be a stripped thread....these are just thoughts to consider before you go again on your merry way....

[luvrbus]

I doubt their GM has a dual air system Donald from the photo it looks like it blew off at the supply port which is under pressure all the time on their setup  

These old buses you can find very creative plumbing and wiring sometimes when I try to help people with problems I wonder sometimes what the hell is this thing doing on the road 

They should be on the road  he found the TR-3 this AM

good luck

[eagle19952]

based on their "odd" brake cans (referred to as "mini-mags) I assumed that some one updated the system.....or better said "modified"....
On a different note...the new air dryer is referred to as a an Armada brand...one that I have never of, now I have heard of Armada replacement dryer cartridges...not sure of them, but heard of them.