M105A2 Brake help needed.

[jimm1009]

I need to speak with someone as soon as you are avialable on troubleshooting the brakes on a '77 or newer M105A2 trailer with the dual air lines and reserve air tank, etc.
Is there anyone out there that has real experinece in maintaining these model trailers?
Brakes seem to work find until unhooked from Deuce and then they don't release so you can push the trailer around by hand.
I'm reading the TM while monitoring the PM section & e-mail for response.
I'll call you so it will be on my nickle.
Please PM or e-mail me.
jimm1009 here on S.S.
or jimm1009@yahoo.com

 

[rosco]

The air tank/reserve air is designed to provide brakes in an emergency break away, or if the air pressure drops below the minimum 60 psi. The tank will have a check valve (to keep air from escaping from the hose end), and an air valve, called a relay/emergency valve, that will apply the breaks, using air from the tank to apply them, in the event that there is a disconnect from the vehicle. If the air brake chamber is simple, the air from the tank applies the brakes directly. In newer vehicles and there is a double air chamber that has a big mean spring in it (called spring brakes), the air holds the spring pressure away from applying the brakes except in an emergency.

In order to roll the trailer around, once disconnected from the tow vehicle, you must get under the trailer and bleed off the air from the tank. Bleed the air off, then close the bleed/drain valve again, so that you are ready to go again, when you re-hook the trailer.

The two lines on the truck, one provides constant air for the trailer's resovir, called Emergency Air -right side of vehicle, and the left side provides Service Air. The service air, does not apply the brakes! It provide a signal to the Relay/Emergency Valve, that causes it to open, allowing air from the trailers air supply tank, to apply the brakes. A good trailers air system will hold air indefinatly and keep the trailers brakes on. but usually, the air will bleed off, after a while, allowing the trailer to roll away. That is why they went to "Spring Brakes" on newer commercial vehicles.

Lee in Alaska

 

[mikew]

First off, I'm no expert...

I just built a trailer using a deuce bed mounted on an extended M105 frame (two frames spliced together). I have the same brake system as you do.

If you open the drain valve on the reservoir tank and let the air out, the brakes will release.

 

[jimm1009]

Just got off the phone with Lee and it seems that the air system will retain a charge for a while and must be drained through the sump valve (drain valve) in order to free wheel the wheels and push the trailer by hand.
Wonderful news for me but I will be exploring some other minor issues for GP.
Did I say "what a great site this is"?
It's so nice to be able to tap into the "Main Server" of MV talent when you run into a problem and get stumped.
jimm1009

Picture needed
Could someone take a underside picture of their M105A2 trailer for me?

I need a picture this morning taken from the bottom side at the tongue looking up an to the rear that shows the air tank and shuttle valve for the brake system on the A2 with dual air hoses that connect to the truck.
I've been told that these are 1977 and newer but can not prove that per the TM.
I think that I may be missing something on the air shuttle valve so I really need a good picture showing the bottom of the valve and the drain for the air tank.
Question #2. The TM does not state anything about having to drain the air tank on this model trailer before attempting to move it around by hand.
Can someone clarify if you must drain the trailer air tank prior to attempting to push it around by hand just after releasing and uncoupling from a deuce.
The trailer brake system would have some air charge remaining in it.
Is this normal? TM is not specific here.
I may have caused my own problem here. The trailer had the valve broken off and I have temporarily placed a pipe plug in the hole where the drain should be but I do intend to place a drain valve there shortly.
Again, the TM is not specific in this area (TM9-2330-213-14&P paragraph 2-12).
jimm1009

 

[Motorcar]

Question #2. The TM does not state anything about having to drain the air tank on this model trailer before attempting to move it around by hand.
Can someone clarify if you must drain the trailer air tank prior to attempting to push it around by hand just after releasing and uncoupling from a deuce

Exactly what ROSCO said above in his reply, you can go to NAPA and get a drain valve for the air tank and fix your problem in about two minutes. Open the valve, let air out, roll around if you are a strong guy or have help. Good parking brakes or chocks are a must.

 

[jimm1009]

He was exactly right...hit the nail on the head.
Boy dooooo IIII feel STUPID!

But silly me, as I have to ask. Why does the TM not make mention of this
trivial little matter?
Immagine unhooking your empty trailer for the day and you need to move it 2 feet by hand cause it is off the mark by that much. Imagine the brakes are locked up and it take 200 guys to move it 2 feet.
My M1009 would not budge it in the rocks but it sure did want to dig a hole!
Live and learn!

I hope this stupidity on my part helps others with the same kind of brake system in case they run inot the same "problem".

jimm1009

 

[Recovry4x4]

There is a section in the TM indicating the year 77 for dual lines and the relay valve.