W500 Air Brakes help needed

[Connecticut Yank]

I have a W500 with what appears to be air brakes. There is a gauge on the dash and a big tank on the drivers side of the frame.
The truck is inop so I have no idea of the system's operability.
Can anyone tell me where I can read up on how such a system works and how to maintain it?

[712edf]

Are you sure its not a vacuum gauge? My W600 also has large tank on the driver's side frame rail, just under door. This is part of the booster system. You will find that in addition to the single chamber master cylinder on the firewall, there is a booster & another cylinder mounted on the inside of the driver's side frame, about opposite of where that tank is located.

My guage reads about 22 under normal driving conditions.

Bucky

[712edf]

Locate a factory service manual for the year model of your truck. They cover 100-800 series trucks, are about 2 or more inches thick. They are like bibles. Scripture doesn't fail lol.

They turn up on ebay, but I think a member here or on one of the Dodge truck forums has them. Expect to pay $25-50 bucks, depending on condition/year/shipping. Worth every cent.

Bucky

[W_A_Watson_II]

For reference, here is a pix of my W500's Dash. The Vacuum gauge is the one above the Heater and Wiper switches.

[Connecticut Yank]

Are you sure its not a vacuum gauge? My W600 also has large tank on the driver's side frame rail, just under door. This is part of the booster system. You will find that in addition to the single chamber master cylinder on the firewall, there is a booster & another cylinder mounted on the inside of the driver's side frame, about opposite of where that tank is located.

My guage reads about 22 under normal driving conditions.

Bucky

I truly am not sure. What you describe is what I have but this is what the gauge says : Air Pressure Brake. See picture.

[Tom Petroff]

Sounds like you have air over hyd. brakes.
Some trucks were equiped that way.
Basicly a Hyd brake system with an air operated booster.
You have a compressior on the engine?
TGP

[Connecticut Yank]

You have a compressior on the engine?
TGP

I don't know if there was a compressor as a lot of the peripheral stuff on the engine is missing.
It is a bus- like a school bus.
But never used for school kids at all.
And when the snow clears I will climb in and over it.

[712edf]

While I haven't personally seen air over hyd brakes on a 500 series, they did come on larger trucks. Maybe the fact that yours is a bus has something to do with how it was equipped.

My vacuum gauge reads from 0 to 30.

If all of your plumbing was present, following where the tank is connected would tell you if its vacuum or pressure. Vacuum tank would be hooked to the intake manifold, pressure tank to a pump ( likely belt driven) like Tom mentioned.

Bucky

[W_A_Watson_II]

Oh, that is a nice W500 School Bus!

[Jeff in N.Tx.]

If your gauge has readings up to 130 or maybe even 160PSI, then you most likely have air brakes. Vacuum brakes would have a much lower pressure limit as was previously mentioned. A large diameter brake cannister at each rear wheel, connected to the brake pads with some type of linkage, will indicate air brakes. A push-pull knob on the dash could be another indicator of air brakes. You might not have any brakes on the front axle, as they were not required yet on that model year of truck.

[W_A_Watson_II]

The center of the dial on that gauge is a factory matching gauge. Mounted in a different spot than my '64. Do you have that picture in a larger size? What year is this truck?

[Connecticut Yank]

The center of the dial on that gauge is a factory matching gauge. Mounted in a different spot than my '64. Do you have that picture in a larger size? What year is this truck?

It is a 1963.
BTW your W500 fire truck is very nice.

[dougdodgeman]

My 2 '69 D-500's have air over hydraulic brakes, just as Tom talks about. Also has that gauge on the dash, and were set up for air brakes for a trailer, as well! Doug