Dump valve question...

In an earlier thread around 11/2012, I posted that I installed an elec dump valve for the REAR axle of my trailer.
It works as expected and its connected up correctly.
However, the other day I noticed something odd - but not sure if its normal.

I had accidentally hit the dump switch in the cab and didn't realize it.
I wasnt moving the rig at all (and it was empty)- but heard this air leak and watched the air gauge dropping, even while the engine was running.
The air comp was keeping up but cycling of course.

Prior to discovering the switch was active, I crawled under, looking for the air loss and noticed the following:

1. Front axle air bags were fully extended
2. Rear axle air bags were totally soft
3. HCV arm was in the DOWN position, and as such attempting to apply air into the system.
4. HCV exhaust port was blowing air - I suspect due to the forward air bags as full as they could be??


Seems though, since the HCV is located on the rear axle and I have dumped it, it continues to call for air but I dont know if thats normal and why its blowing out the exhaust port on the HCV.

Any thoughts...?

 

Thanks Carrkool....
See thats what I was thinking too. So maybe I am indeed onto something here. ######.

Now, my HCV has several connections:

-Input
-output 1
-output 2
-exhaust

Output-1 goes direct to the front air bags and output-2 to the dump-valve and then to the bags.
I was very correct on how I installed this.....I even went so far as to snap photos and send them to a tech at Hendrickson to see if I had this down. My only issue appears when I have the dump valve activated.

Else wise it all works fine at least.

it just seems odd to me...

 

I was hoping you would chime in. I almost sent you a PM...you were heavily involved in a thread about this.
Could you explain though...?

Something isn't clicking inside my head. I guess I figured if the air was cut off to the rear bags the front would carry the trailer (especially when empty) but I am at a loss as to why the air is continually escaping out the exhaust on the HCV when its trying to call for air.

I suspect the front bags are as full as they go but dunno why the valve then dumps the air flow from the supply.

 

Thanks for the clarification. Its appreciated...
I only use the valve when parking - or when idiot me accidentally hit the switch.
I wonder why the HCV itself is exhausting when trying to raise the bags though. The solenoid would shut off the air flow to the rear axle bags. Maybe it has some pressure valve in it....I might ask Hendrickson.

I'm likely way overthinking this as usual...

 

I thought when I installed/tested it that it worked as you described.
....let the air out and then dead quiet.

Thats what I remember....I dont know what would have changed unless the solenoid isnt closing all the way and 1/2 way
open and 1/2 way closed.. But air going out the EXH port on the HCV is weird.

I will call Hendrickson in the AM and then eventually double check all my work, but if it was wrong to begin with it should have been this way since day 1.