M923a1 air brake question

[topo]

Farmallmilitary Google wedge brakes . There are some Utube clips .

 

[M35A2-AZ]

On each of the rear axles there are service brakes and spring brakes. The bigger ones are the spring brakes, used for the parking brakes.

 

[Farmallmilitary]

Doesnt the larger one have spring brakes as well as a service chamber as well. In other words dosnt the larger one have two chambers, 1 for service and one for spring brake which would be the emergency brake if you lost all pressure in the system. So how do I tell which one it is? If the larger chamber was the spring brake then it would probably be leaking if the truck was pressurized with the brakes disengaged. If i push the brake peddle and it starts leaking then it would be the service pod/smaller pod right. Also when i take off the pods i am pretty sure you have to cage the brakes in order to take them off. I am guessing they just twist off. If i got anything wrong please correct me.

 

[M35A2-AZ]

Doesnt the larger one have spring brakes as well as a service chamber as well. In other words dosnt the larger one have two chambers, 1 for service and one for spring brake which would be the emergency brake if you lost all pressure in the system. So how do I tell which one it is? If the larger chamber was the spring brake then it would probably be leaking if the truck was pressurized with the brakes disengaged. If i push the brake peddle and it starts leaking then it would be the service pod/smaller pod right. Also when i take off the pods i am pretty sure you have to cage the brakes in order to take them off. I am guessing they just twist off. If i got anything wrong please correct me.

Yes the larger one has the spring brakes and a service side. The smaller one just has the service side.
If you load the P2P Softwhare here on SS it will help you understand how the system works.

http://www.steelsoldiers.com/showthread.php?79228-TM-s-for-the-939-series-trucks

The M939 MV truck have a lot of air lines under them.

 

[doghead]

You can remove and plug an airline, to determine if that is the line with a part failure(downstream).

Often you can hear the air in the line(flowing), or even feel it.

 

[Farmallmilitary]

I tried downloading the p2p file but on both my computers were unable to read the file. Anybody have a different format of the file that may work with my computers? Also when the truck is building pressure and the compressor is turning isnt there a pressure valve that releases pressure when the compressor cuts off? The air system doesnt get above 120 psi and the compressor kicks in around 90 psi, but if im not mistaken shouldnt there be that hiss of air when the compressor cuts off. Is the valve right next to the compressor?

 

[Artisan]

Farmall I have been trying, hard, to make heads and tails of the myraid of manuals
available for the M939 Series of trucks we own.

I am trying to find a way to get a definative list of TM's we want, that are
the MOST recent printings and that are pertenant to only the M939 Series trucks we drive.

After I know I have a good list w/ the associated DL's it will be fun(?) to print
them off and fall asleep flipping thru the pages at night. PLUS I want to carry
many of these TM's in the truck! THAT is probably what drives me the
hardest to attempt nail this down. Right now I am too much of a noob to take this
truck into the sunset w/o these books in case of breakdown. If I were rich
I would just call a tow...I am not.

I ran across 2 TM's a few days ago that might be of some help to you and that I
do believe are not available in the SS's TM M939 D/L area. If these are wrong
someone please tell me...

EDIT: THE FILS I LINKED TO WERE FOR 800 TRUCKS. I FOUND A HONEY HOLE
OF NEWER FILES I WILL LINK TO HEREIN SOON...

If these are good files I hope management grabs them and posts them in the TM section for others,
they will not be on my server forever. There are like 9 and 6.5 MEGS Each.

What I REALLY want is to get ALL the latest files in one spot
and then PRINT myself a copy of each as well. I am just way too much
of a noob to nail this down definatively, yet. It is tough. I gotta be
sure, I do not want to spend cash to print stuff then the next day
find I printed an old book or an adulterated book w/ info some Joe
changed on his home PC.


The TM-9-2320-272-10 file here in the SS TM939 D/L area on this board is year 2004 flavor,
HERE is the 2012 flavor...again feel free to rip it and post it if you find it correct doghead
( I think I saw you were sub'd here ). That is the best thing actually, get all files on this board
up to date and loaded, w/ every TM know to man in it. I just made 3 contributions ( I think )

 

[Farmallmilitary]

Thanks those files are exactly what i need.

 

[Artisan]

I tried downloading the p2p file but on both my computers were unable to read the file. Anybody have a different format of the file that may work with my computers? Also when the truck is building pressure and the compressor is turning isnt there a pressure valve that releases pressure when the compressor cuts off? The air system doesnt get above 120 psi and the compressor kicks in around 90 psi, but if im not mistaken shouldnt there be that hiss of air when the compressor cuts off. Is the valve right next to the compressor?

I do believe you speak of the "Air Pressure Govenor" . 90 and 120 sounds about right to me.

Do the COLA test Farmall. You gotta learn that bro. It is hard to deal w/ all this w/o
having someone teach you the theory as you go. I mean you can watch this
video but I do not think one time the teacher says the word "Govenor" to explain
why this and that is happening and why we do it...

I was taught that it is wrong to assume there will always be a sneeze of air and
that you are supposed to watch the gauge, not listen for a sneeze. What if it sneezed and
you were only at 91PSI?, that is why I was tought to not trust a sneeze.

Remember I am learning here too Farmall, hopefully
someone else will chime in.

 

[ARYankee]

I've got a training handout for the 939 series air brakes. I have it here: https://www.facebook.com/groups/416679351736973/

 

[juanprado]

The 23 series have just been released recently and are vastly superior for troubleshooting with the flow charts. They have troubleshooting flow charts that use the abs midland info center and also with out it. They replaced the earlier 24 series.

See this thread and download this 5 part goodie!
http://www.steelsoldiers.com/showthread.php?93023-The-Mother-Load-of-TMs

 

[Farmallmilitary]

Success i found the leaks. Yeah unfortunatly more than one but I finally found them after crawling under the truck for an hour. Ok so I took the white line off the chambers like you guys told me to do and felt if there was any air coming out of the chamber. I started at the back of the truck and always felt air coming out of the lines not the chambers. So i went to all 8 service chambers in the rear and nothing. I was getting kind of annoyed but then i went to the right front and no luck. So like it always is, it was the last one, the front left chamber. It was shooting tons of air out when i pushed the brake, so i capped it off and did part of the COLA test, holding the peddle down for 60 seconds and seeing if the system lost more than 4 psi within that period. It passed, which made my day. The other leak was in the rear left spring brake chamber. I knew this when i had all the brakes released and it was blowing out air. So only two pods need to be replaced!
My next question is how do i get them off? Do I have to pull the hub off to release the arm? Or do i just cage it and unscrew it?

 

[rangereter]

Your not replacing "pods", you will be replacing the rubber diaphrams ($5 +/- each) more than likely... However, you still could be losing your air from rusted housings, in which case you would/should be replacing the assemblies ($$$). To replace the #12 rubber diaphram in the steer axle chamber, just remove the 5/16" bolt holding the clamp on on the two chamber halves...pay attention to the orientation of the diaphram when you remove it, clean any rust or corrosion on mating surfaces, install the new diaphram, center the rubber in the middle of the housings and re-clamp. Test the same as you diag'd.
To replace the park brake release diaphram in the rear maxi's, cage the p-brake chamber (tighten the caging bolt until you have compressed the internal spring, when caged completely, you will have run the nut down most of the way onto the caging bolt)...remove the spring brake section of the assy from the center section as you did the steer axle service brake assy by carefully removing the two adjacent 3/8" bolts, when removing the clamp do not have your face in front or near the assy in the event that you did not completely cage the spring brake spring...then orient and replace the #16 diaphram. If you do not feel comfortable replacing the maxi's spring brake diaphram...then cage the maxi as above, and remove the clamp on the service side of the assy with the one 5/16" bolt. With the "piggy-back" assy removed from the brake rod tube, take it to a truck repair shop and they should be able to install a new diaphram on the emergency/p-brake side of the chamber. Remember to orient the chambers when installing to facilitate air line connections. Above all else, treat the p-brake chamber assy's (emergency side of the piggybacks) with care...do not drop or handle carelessly, the park brake spring is about 3/8" in diameter and several inches long, is under compression while in the chamber (caged with bolt or not), it is a relatively large spring under compression and has more than enough stored energy to injure or kill. Always be conscious of this, if you don't understand this procedure, don't attempt this repair. If these chambers appear rusted, damaged or deteriorated in any way, get a truck mechanic (who has experience with these older assy's to help you out. I am not trying to scare you out of fixing your own equipment, just letting you know that these piggy-back chambers have not been made with removable spring brake clamps for over 20 years due to the amount of injuries incurred by even veteran mechanics not being careful when servicing. Regard's
Bob

PS: Be safe, and if I have missed something here, anyone please chime in.

 

[Artisan]

Farmall,

I eff'd up and gave you 800 series files back in post #47...I think there VERY close
but you should delete the files I sent you back in post #47 and
take a look at these files me think's...

I think these are the 5 files JuanPrado speaks of...

The DL's are HUGE, click and take a nap!

These files I think were sent to patracy by Juan so eventually they will
prob get uploaded here on the SS site in the TM area.

M939 SERIES

FIELD MAINTENANCE MANUAL #1

FIELD MAINTENANCE MANUAL #2

FIELD MAINTENANCE MANUAL #3

FIELD MAINTENANCE MANUAL #4

FIELD MAINTENANCE MANUAL #5

IF ANY INFO IS WRONG PLEASE TELL ME!

( But the wife is out now buying me a thumb drive to put these and
other files I have that are updated ) ..and I am gettin' it done.

 

[Farmallmilitary]

Thanks artisan i have been reading those manuals for the past few hours and have now figured out how to take the pods off. It even showed me how to rebuild the service chambers but not the spring brake chambers. I will probably end up rebuilding the service chamber and the taking the spring brake one to get rebuilt by a proffesional. I would probably be able to rebuild to rebuild it but for everyones safety as well as mine I think I will just pay a few more bucks to get a pro to do it. Hopefully I can get this beast working properly. Also artisan you have a m925 right, mine is a m923 and it has the winch controls in the cab but no winch. Do you have any clue why they would put the controls in but no actual winch? Just wondering.

 

[73m819]

Thanks artisan i have been reading those manuals for the past few hours and have now figured out how to take the pods off. It even showed me how to rebuild the service chambers but not the spring brake chambers. I will probably end up rebuilding the service chamber and the taking the spring brake one to get rebuilt by a proffesional. I would probably be able to rebuild to rebuild it but for everyones safety as well as mine I think I will just pay a few more bucks to get a pro to do it. Hopefully I can get this beast working properly. Also artisan you have a m925 right, mine is a m923 and it has the winch controls in the cab but no winch. Do you have any clue why they would put the controls in but no actual winch? Just wondering.

your truck was a marine truck, they took the winches off to save space when loading on ship

 

[ARYankee]

Farmall,

I eff'd up and gave you 800 series files back in post #47...I think there VERY close
but you should delete the files I sent you back in post #47 and
take a look at these files me think's...

I think these are the 5 files JuanPrado speaks of...

The DL's are HUGE, click and take a nap!

These files I think were sent to patracy by Juan so eventually they will
prob get uploaded here on the SS site in the TM area.

M939 SERIES

FIELD MAINTENANCE MANUAL #1

FIELD MAINTENANCE MANUAL #2

FIELD MAINTENANCE MANUAL #3

FIELD MAINTENANCE MANUAL #4

FIELD MAINTENANCE MANUAL #5

IF ANY INFO IS WRONG PLEASE TELL ME!

( But the wife is out now buying me a thumb drive to put these and
other files I have that are updated ) ..and I am gettin' it done.

Sweet!!! More manuals to help me out. I thought that I had all of them. Thanks

 

[73m819]

I've got a training handout for the 939 series air brakes. I have it here: https://www.facebook.com/groups/416679351736973/

WHAT about those that do not do face book crap, your link is worthless to those because it REQUIRES a face book sign in

 

[Farmallmilitary]

Wait does that mean my truck WAS an m925 but no longer one? The plates say m923.

 

[73m819]

yes, I also understand that the trans pto was left on the trans, just the winch kit was removed