CTS2
Junior Member
Posts: 70
Likes: 27
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Post by CTS2 on Aug 23, 2022 3:56:31 GMT -6
I have a Mack CHR with Neway air suspension. There is a button in the cab to dump the air. As far as suspension goes, it works fine. But I have two problems. The first is that it would make more sense if it was a switch to dump the air and leave it dumped, instead of a button that has to be held. The second is that it really doesn't work. When you push the "press and hold" button, air releases from the two valves, one of which is in the photo, the suspension drops a fraction of an inch, and nothing more happens. The air continues releasing as long as you hold the button, but the suspension never drops enough to be any use. It's as if the dumping part works, but it continues inflating at the same time. I'm pretty sure it shouldn't do this. Any suggestions as to where I should start?   |
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Post by meskie on Aug 23, 2022 7:51:41 GMT -6
Sounds like the valve isn’t dumping the air from the suspension just from the supply line. I haven’t seen a suspension dump where you have to hold it in but it isn’t hard to put a regular dump valve in. I’ve put a couple on trailers that didn’t have one.
You can either dump all the air through the switch or have a relay switch to dump the air through the valve located close to the suspension.
As I’m typing this I’m wondering if you relay valve isn’t working correctly. They do get gummed up and won’t allow the valve inside to completely move.
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Post by Beerwiser on Aug 23, 2022 10:33:11 GMT -6
I am with Meskie. Something is not right in the dump valve or the button. I am leaning toward the button just because I had oil build up on my switch at one point. I ended up taking off the output line on the switch at the dump valve and let it blow all the crap out. It was restricted enough that it wouldn't fully open the dump valve. Even more likely if that button only has 1/8 line on it.
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CTS2
Junior Member
Posts: 70
Likes: 27
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Post by CTS2 on Sept 16, 2022 6:18:57 GMT -6
Would I be correct in thinking that maybe these dump valves are operating correctly, but there must be another valve to block the supply of air to the circuit somewhere else that I haven't found yet? If so, maybe this unknown valve might be jammed?
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Post by northernfarmer on Sept 16, 2022 6:55:54 GMT -6
I was asking a friend who works on trucks and their frac equipment about the air bag circuit and his familiarity is with the Paccar trucks and mentioned there were two different methods of air supply to the bags depending on the style of air dryer for that brand of truck ( Pete or Kenworth ) but the actual functionality in both cases is all about the levelling valve itself with check valves inside that cause it to dump air if the cab switch is switched to the dump position but that air pressure is always present to the leveling valve once the trucks system is pressured up. Put another way, as long as the truck air pressure is present and getting to the levelling valve everything is happening within that one valve. Now that is not to say a Mack or that particular suspension brand doesn't have some other system as he would know nothing about a Mack and I expect the easiest is to ask someone familiar with your vintage of Mack as well as that suspension brand to find out how its system works and what if anything you have not realized is in its setup or how it should function. It sure doesn't make sense to me why one would have to hold the valve but I've only driven a Mack years ago that had no air suspension ...
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