CTIS Quick release valve

[RAJ LMTV]

Does anyone know if there is an aftermarket replacement for the quick release valve on the front wheels of the LMTV? Mine have slow leaks and are becoming a nuisance with low tire pressure if the truck sits for a couple of days. Even a replacement like the rear wheels would be fine where there is no quick release, just a solid L valve.

Thanks

 

[Smike740]

The rears are available new from Spicer Dana, I purchased 2 a few months back from Find It Parts. If you google the NSN you should be able to find the Spicer part number. If you have trouble let me know I might still have the box in the garage with the part number on it.

 

[RAJ LMTV]

Thanks Smike. I'll do a search and get back with you if I can't find them.

 

[RAJ LMTV]

Well I was able to find the NSN for the front kneeling valve in the TM but no luck locating the part number for the rear valve. If you happen to still have the part number I would appreciate you posting it.
Thanks

 

[KGBruce]

Missing CTIS air hose

Hello everyone! Fortunate to have access to this great community. Just acquired a 1998 M1078 this past weekend. Purchased in a "Non-Running" condition with little to no knowledge of its troubles or history. Ya, I know!! LOL!
i actually have it running already after landing all of the wiring that had been disconnected from the back of the CB panel.
I thought I was in some serious trouble until discovering each and every wire has its home address stamped on it.
Anyway, so now I have discovered a massive air leak coming from a missing airline on the bottom,front,center of the cab. (Visible only when the cab is raised. Looks like one of several parts that have been pillaged from this truck. My problem is identifying what this connection looks like along with its configuration. I've looked over quite a few diagrams of the CTIS system and have yet to find any decent pics on the bottom of the cab. I wish I could look at another truck to get a perspective but I'm kinda all alone here! Would anyone have any info or pics of this section of airline? The pic on the right is the center, bottom of the cab where all the air escapes. The pic on the left is a view under the front passenger side of the cab where I assume the is the other connection point.

 

[tennmogger]

In picture number 2, that non-terminated fitting is an exit vent from the brake treadle valve. Nothing missing I think. I had a bad leak out of that fitting and the problem was sand and gravel in the treadle valve. Of course there are no brakes (except the parking brakes lock up) if there is no air remaining.

I had to take apart the treadle valve to clean it out. There is a thread covering that, which I will edit in after I find it.

There could be other problems too.

Edit: read this thread: https://www.steelsoldiers.com/showthread.php?154348-LMTV-air-brake-problems

Entry 57.

 

[KGBruce]

Interesting! I just figured another air hose missing. So I will research how to clean the break treadle valve. I just need to get the system to pressurize and continue ruling out any more leaks. Much appreciated! Really been racking my brain to figure out what was missing...... So pic #1 looks normal as well? Nothing missing there either?
Thank you!

 

[coachgeo]

BTW there are a couple of these trucks in MO. try the members list searched by state and LMTV?

UPDATE: well that search method sucked. did several other search ways for you.

Here is some

https://www.steelsoldiers.com/member.php?11355-sargentwolf
https://www.steelsoldiers.com/member.php?1858-Overdrive
https://www.steelsoldiers.com/member.php?69681-Webrep
https://www.steelsoldiers.com/member.php?33656-hcso2332 Not sure if he still has one or not

 

[firefinder]

KGBruce,

There are several FMTV owners in Missouri as coachgeo said. I sent you a PM with contact info.

Stay safe and stay in touch,

firefinder

 

[tennmogger]

Does anyone know if there is an aftermarket replacement for the quick release valve on the front wheels of the LMTV? Mine have slow leaks and are becoming a nuisance with low tire pressure if the truck sits for a couple of days. Even a replacement like the rear wheels would be fine where there is no quick release, just a solid L valve.

ThanksView attachment 655838View attachment 655839View attachment 655840

A valve like this (used for "kneeling" the truck) caused me a lot of hair pulling. That tire had a leak that I could not find. It seemed to leak when driving it but usually stopped leaking when stopped. Sometimes it continued leaking and the tire would go down.

That heavy valve and it's hose are threaded onto the stem coming from the wheel. There are threads on the stem backed up by a tiny o-ring. The stem threads on my tire were barely holding and the o-ring was worn so when the wheel was spinning the weight of the valve (centrifugal force) was letting the air out.

Another good reason to replace this type valve.

 

[Ohiobenz]

I thought this was the quick release valve?

 

[Ohiobenz]

For the benefit of Science, and since I found a reasonable priced replacement on fleabay, I decided to disassemble the front QRV.
Basically it is nothing more than a differential pressure valve with a rubber flapper in between the upper input pressure and the vented chamber into which the 2 hub lines go.
When the pressure of the input is higher than the wheel/hub pressure the flapper is pressed against the exhaust/vent port and sends that input pressure out the hubs. When the input pressure is lower than the wheel/hub pressure the flapper is pushed away from the vent and exits until it is slightly lower than the input pressure, at which time the flapper closes.
There really is very little that can fail other than a dried out rubber flapper which would allow air to leak out of the wheels/hubs while the input is continuously trying to reach it's set point.
I'm sure that would cause deflated tires and a fault on the controller for failing to reach pressure.
The only way to test it would be to plug both outlets and apply pressure at the inlet. Any air escaping from the the vent would mean either a bad flapper or dirt inside of the unit.
Hope this helps.