PCU safety relief valve on M932A2

[Shovelbum]

Does anyone know the PSI rating of the pressure relief valve on the Pneumatic Controller? I thought it was 120psi?

 

[doghead]

You need to list a state in your location. Site rule

Did you read any of the other threads posted on this topic(3 today I think)?

Used to protect the air brake system from accessory failure.
Open Operating PSI 65 ± 8, Close Operating PSI 56 ± 8
Inlet Port 1/4" NPT, Outlet Port 1/4" NPT
Accessory Port B 1/4", Accessory Port C 1/8"

 

[Suprman]

There is a 150psi relief on the abs air dryer if your ppv fails closed this valve will vent so you don't blow something

 

[Shovelbum]

Thanks for the info...this site has been a big help....Sorry about the location...did not see anyplace to put it (New Mexico)! I searched the treads but....so I guess I proved I'm not a computer guy!

 

[doghead]

Was the info I posted right for the part your refering to? It was from this thread, http://www.steelsoldiers.com/showthread.php?118320-Pressure-relief-valve

If you need more info, it's a good idea to look up the part number in a part TM, then google it. If you see a "parttarget" link, click on that for detailed info.

 

[Shovelbum]

Actually I am talking about the pneumatic control unit (pcu)pressure relief valve or safety relief valve (mounted underneath the winch control tower on a M932A2)...not a pressure switch. I have read through just about every TM that is related to tyour helphe CTIS system on the truck....just can not find any reference to the pressure rating for it. I did a NSN part search for it and they wanted 300.00 for it...not doing that!!!

Thanks for your help!

 

[Suprman]

On the ctis valve body in the cab? What is it doing?

 

[Shovelbum]

That is correct. It is not holding any pressure...just venting. If I hold it closed, my ctis works like it is suppose to....my finger is getting tired so I would like to install a replacement relief valve! Just can not find what it is rated at...I'm guessing over the 60 psi for the fill side of the ctis as far as tire pressure goes that is? The 65psi sounds like it would work?

 

[Suprman]

There is a small catch trap on the air feed line into the valve body. You can usually screw a schrader valve into it. You should be able to replace the safety relief on the ctis valve body with something generic from napa. Or just plug it and see his it goes. I have a tested good complete valve body here.

 

[Shovelbum]

That is good to know! I had installed a 120 psi valve that I had on hand, my tire pressure went to 75 psi with the solid red Hwy light on the ECU, so plugging it may not be my best option. I think I will get a generic 65 psi valve and see how the tires respond to that!

Thanks again for your help!

 

[Suprman]

Air is not supposed to come out of that valve. Highway pressure should be around 65psi but 70 is not unheard of. You may have a faulty pressure sensor. It's sticking out the side of the valve body.

 

[Shovelbum]

Good to know on the tire pressure. I will try to ohm it (PCU transducer) out per one of the TM's instructions.

Thanks!

 

[Shovelbum]

Turns out that the valve I was working with is nothing more than a "relief valve" with a lite duty spring which pulls the little dust cap back in place.

I have now replaced the ECU and the PCU with a manual regulator assemby. I fabricated a bracket that mounts to the same location as the ECU did (shut off valve, bleeder valve, gauge, and reg) and it works fantastic! I can now set my tires to any pressure I want...no preset PSI points also no more single point failure components (transducer, pressure switch, ECU, or PCU). I got the idea from a Soviet Katyusha rocket launcher we have here on site.