Do brake chambers have brake fluid in them?

It's only air in that chamber. Fluid breaks down, air doesn't

 

The only fluid you'll have in them chambers is water splashing from a wet road.

The only brake fluid semi's have is the clutch.

 

Fluid will burn at the temperatures that we do braking downgrade in mountains. You cannot find fluid strong enough to endure that kind of condition without catching fire. You also cannot use fluid to apply the required force to generate that kind of braking power.

What does?

Air. Compressed air, and a hell of alot of it.

 

OMG, you have GOT to be kidding? They're new all right and I thought I heard it all.

 

i realize that you have a question, and asked it here, it's better to ask, then to either assume, or make mistakes at the DMV test site.

however, if you are in any CDL school right now, that question would have been better asked to your instructor(s). in fact, your instructor should have told you it's an "air system", which would mean, no fluids of any kind in there.

on an outside "chance" your truck has a bad air-compressor, there "might be" a trace of oil seeping out, but in all my years, i have never seen that...

so " NO audible leak" would be all that you'd be saying...

 

I'd make a terrible instructor, there would be an even bigger driver shortage. BRAKE FLUID? GET OUT

 

but you know something.??

it would not surprise me, if someone had a grudge against a company, and did pour "some sort of fluids", into the glad hands, and reconnect them. just like the old penny trick into the grommets.

 

Heavy, I do respect your continued contribution to this forum.
But this time, you're absolute wrong.
The air itself does not produce any friction to slow down the vehicle, it is the brake liner. And for the brake liner, there is no difference what made the necessary movement to turn the cam and press it against the drum. It could be as well any hydraulic system.
A bydraulic system provides even more than a 140 psi of pressure.
The reason, why air is used, it's my assumption, air doesn't change its viscosity in cold temperatures whereas oil does. The brake system is not a continuous flow system and would leave cold oil in the lines, making it slow to react in cold conditions.

 

Also, any hydraulic system would need to be bled if they were disconnected anywhere or a break in the lines somewhere.

Won’t be fun being under the truck in -20°c to -40°c weather laying in snow bleeding every wheel on the truck and trailer that got air in the hydraulic system.

Air is a way better and more safer system to reliably work all the time in combinations vehicles.

Every truck that has hydraulic brakes and pulls a trailer, the trailer is either electric brakes or electric over hydraulic.