brake problem. - Steel Soldiers::Military Vehicles Supersite

madsam · 08-15-2008, 23:37

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 · 08-16-2008, 00:24

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

Does anyone know what a Valve Shuttle is?

CCATLETT1984 · 08-16-2008, 01:13

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

madsam · 08-16-2008, 01:27

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 · 08-16-2008, 01:43

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

madsam · 08-16-2008, 02:06

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

CCATLETT1984 · 08-16-2008, 02:09

http://www.steelsoldiers.com/index.p...pic&t=8063

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

madsam · 08-16-2008, 23:32

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 · 08-17-2008, 00:21

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 · 08-25-2008, 14:27

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.