brake problem.

[madsam]

When I push my brake peddle something lets all the air out. All the time when the peddle is down the air is open out the exhaust. As far as I understand, that exhaust is just for releasing the pressure when the peddle is released. So there seems to be an issue between the air in and the exhaust where some valve is not getting closed. I tried tapping on it to knock loose any rust, but got no where.

Has anyone seen this? Does anyone know the manual to look at for a diagram on this part? What is this part called? (Air assist??)


Thanks for the help.

 

[madsam]

I think the Air pack or booster assembly diagram is what I am looking for.

Does anyone know what a Valve Shuttle is?

 

[CCATLETT1984]

I'm sure a few of the guys will have some help for you later in the day, most are sleeping right now

 

[madsam]

Yep. I was hoping to take the truck to a parade tomarrow.. But with bad brakes...

I can't find any diagram for the air pack itself, only what it looks like. But no internals.

I figured out that the 'valve shuttle' is a valve that can take 2 inputs and run a device wit one output.

 

[CCATLETT1984]

there is a rebuild diagram for the deuce, but i know the 5ton airpack is different

 

[madsam]

Where? on this site? I did a search, but did not see anything.

 

[CCATLETT1984]

http://www.steelsoldiers.com/index.php?name=PNphpBB2&file=viewtopic&t=8063

TM 9-2320-209-34-2-1
that's the TM for the m35 airpack.

 

[madsam]

I think the brake system is something like this - Air boost hydraulic system. Except there is only one booster unit. This is a blurb from the document:

Air–Boost Hydraulic Brake System
(Air Brake Endorsement not Required)
An air–boost hydraulic brake system uses air pressure
to assist brake force. This is similar to vacuum–assisted
brakes on most passenger vehicles. An air–boost system
usually has the same components of a standard air
supply system including a compressor, governor, wet
and dry reservoirs. These components are found usually
in the same places as on a full air brake system.
The brake pedal linkage operates a hydraulic master
cylinder that sends hydraulic pressure to the booster
unit. Initially, at low pressure the hydraulic fluid passes
through the booster and begins to pressurize the wheel
cylinders moving the brake shoes out to the drums.
These booster units are similar in operation to
“Hypower” or “Hydrovac” vacuum boosters found
on most light and medium weight vehicles, but air
pressure is used to intensify the hydraulic pressure
generated by the master cylinder rather than vacuum.
Built into the booster unit is a hydraulically operated
air control valve.

This is where air from the reservoir is directed.
As the pressure from the master cylinder increases,
the air control section in the booster will open
and begin to deliver air pressure to the rear of the
air cylinder. The air cylinder pushrod transfers
pressure on a piston in the hydraulic section of the
booster, increasing the hydraulic pressure at the
wheel cylinders.

The driver has full control of the braking force as
the air control section modulates the boost pressure
in proportion to the master cylinder pressure.
If the vehicle was to lose all of the air pressure
the brake system would lose the air assist boost,
however the hydraulic system would continue to
work but at reduced effectiveness. An air brake
endorsement on a driver’s licence is not required
to operate a vehicle with this brake system. Consult
the operator’s manual for the vehicle you drive for
maintenance requirements.

 

[madsam]

This is what I think it looks like. I will look tomarow to see. Still looking for a booster diagram for the 5 ton.

 

[madsam]

Here is a pic of the booster out of the truck. I am going to pull it apart to see what is wrong with it. My guess, is that there is rust in it somewhere.

 

[Boatcarpenter]

Here is a link to the Deuce airpack pages.
http://www.steelsoldiers.com/index.php?module=pagesetter&type=file&func=get&tid=1&fid=file&pid=98
Go to page 12-7 in the TM. Should also be page 569 of 772 if the link opens in Adobe.
Hope this helps.
BC

 

[madsam]

Thanks. I will look at it.

 

[madsam]

Ok, I have it apart now. And you know a lot of times, things get worse before they get better. Well, they got worse..

It is all able to be cleaned up, but a mess. Lots of rust, and moving parts not moving.

I am amazed it was working at all before.

 

[madsam]

Here is the Shuttle valve. It takes air from two different control sources to control one output.

This is for activating the brakes from 2 different places.

 

[madsam]

hydraulic piston that activates the air to the air ram for boost. This was stuck and did not move. It was stuck in the off position that evacuates the air from the ram. That dumped all the air out the exhaust port.

You can still see some of the rust running out.

The only way to grab the piston was to put a screw with a wire tie to tighten it up to hold. It does not hold real tight, but enough to exercise the piston.

 

[madsam]

Here is the air valve.

 

[gimpyrobb]

Wow, that was nasty! Good job on the clean up.

 

[madsam]

After cleaning up the air plunger, I found a new problem. The end was bent. I think there was ice in the can this winter and it bent the end of the rod. That is when it stopped working. So I cleaned everything up and carefully bent the end back.

I think this truck was in a deep watter place like a hurricane. Lots of rust and water where it should not be.

I think there should be a drain on the can for before winter. But then again, there is not supposed to be watter in it.

 

[madsam]

This truck will be called the wd40 king...

 

[madsam]

I got the air pack all back together today. tomorrow I hope to get it back in the truck. Cross your fingers..