939 Air Compressor Governor Advice

[mkcoen]

And before it comes in: yes I did a search (939-air-compressor-governor-adjustment) and yes I read the TM -24 (1st section) PG 3-576 I believe. I found threads discussing turning up the pressure but no instructions on how they did it.

The governor in the TM does not look like the governor on my truck so thinking it's possibly for an A-nothing not an A2. The TM says to loosen the 1st nut then turn the second nut clockwise to increase pressure. I'm having issues with my home computer PDF reader so I can't copy the drawing of the governor but I've attached a pic of one that is like the one on my truck. Is the plastic knob on the one in the picture a dust cap of some sort or is it the actual means to adjust the governor? The only direction it would move was counter clockwise (like it was being screwed on) so no way to turn it clockwise. My air currently builds to 120psi so it's fine as it is but have read some comments about turning up the compressor to get the CTIS working and wanted to give that a shot.

 

[MtnSnow]

That Is the newer style. I have the Same one on my truck. Unscrew the black plastic cover then use a 7/16th wrench to loosen the jam nut and turn the center stud with a flathead standard screwdriver counter clockwise to bring your cutout pressure up closer to 130psi. Then thing hen the jam nut and then screw the black plastic cap back on and enjoy

 

[gimpyrobb]

http://www.beamalarm.com/Documents/haldex_d2_governor_service_data.html

 

[doghead]

Found this by Google searching "how to adjust air governor".

http://www.bendixvrc.com/itemDisplay.asp?documentID=5644

 

[mkcoen]

Thanks Gimp! That was exactly what I was looking for/needed.

Doghead, looks like the same item only directly from Bendix. And while typing that into Google found it, typing it into the Search function on SS did not. Since it's a military vehicle I zone in on searching here first and apparently forgot there are other places to look.

 

[mkcoen]

Either my governor is screwed up or the instructions are. Turning it clockwise (per the instructions) lowered the cut-off. I adjusted it twice that way and dropped from 120psi down to 115psi and then 110psi. Going back and doing the reverse had the reverse effects increasing approx. 5psi every 1/4 turn. After I got it back to the original 120psi I adjusted it (clockwise) and bumped it up to 125 then 130psi. It's holding that now but had zero effects on the CTIS so it's back to running through the Trouble Shooting manual again.

 

[mkcoen]

.

 

[hklvette]

CCW tightens the spring inside the governor, increasing the cut-out/ cut-in pressure. You have that right. You may want to search through some of the recent threads on the M939's CTIS system. Lots of good information to be found.

 

[MtnSnow]

Mkcoen,

Double check the CTIS pressure sensor which is mounted down by the PPV on the wet tank. If your sensor does not work the system thinks you are below 120 psi and will not turn on. You can unplug the wires going to the sensor and jump the wires which will make the system "see" that your above 120 psi no matter what the actual pressure is. If the CTIS then wants to work you know the sending unit is bad.

 

[mkcoen]

Mkcoen,

Double check the CTIS pressure sensor which is mounted down by the PPV on the wet tank. If your sensor does not work the system thinks you are below 120 psi and will not turn on. You can unplug the wires going to the sensor and jump the wires which will make the system "see" that your above 120 psi no matter what the actual pressure is. If the CTIS then wants to work you know the sending unit is bad.

Thanks but the truck has been gone since last year but hopefully this'll help someone else. Concentrating on the M561 now.

 

[MtnSnow]

Your welcome and sorry I missed that it was year ago...oh well maybe my suggestion will help someone else in the future

 

[Oldworldtenacity]

Your welcome and sorry I missed that it was year ago...oh well maybe my suggestion will help someone else in the future

Yep, it just now helped me out

See, it only took a few weeks into the future lol.