Why airbrakes?

Why do trucks have air brakes and not hydraulic brakes?

 

With air you can replenish a small leak driving down the road. The main reason though is for emergency braking. If you lose break fluid brakes do not work at all, if a truck loses air the brakes are automatically applied.

 

Fluids will BURN on the mountain long before you reach the bottom. Brakes generate massive thermal loads.

Also... in my time, trucks lived and died on air pressure, wipers, engine start, horn, steering, etc.

I would never ever use a fluid based braking system on some of the mountains Ive run.

Air when blown like on a train or 18 wheeler etc travel VERY fast, like near the speed of sound. Much more ability to apply just so much of this or that where you want it. And usually there is more where that came from.

If not? That is where you the professional human comes in with your low air, no air training.

 

You are so full of ####.

 

Because how are you supposed to have trailer brakes? Electric brakes quite frankly suck and have too many possible failure points to be reliable. And hydraulic brakes are no good because it would suck having to bleed your trailer brakes every time you drop the trailer. For RGN guys it could be a dozen times a day.

 

This.

Hydraulic brakes simply wouldn't work dropping and hooking to various trailers...even the smallest little bubble of air in the system and their effectiveness is severely reduced.

 

Air brakes have been proven to work on trains that are over 5 miles long. The design on tractor trailers follows very closely to that of a train. If you lose air pressure the brakes are applied.

The better question is, why dont cars have air brakes instead of hydraulic?

 

Because hydraulic fluid compresses far less than air providing overall better brake feel and quicker response.

 

I can see it now. Idiot brake checker drains his air and gridlocks a entire highway in a morning rush somewhere.

Hell, they are making trucks with airride now and one with jacobs. Why not airbrakes... I would love it. Probably hate it too.

 

It is a safer system all around. In your car, there is a pump that multiplies the braking force of your foot on the brake by something like 360x. Imagine how much multiplication a truck would need. If that pump ever failed you have nowhere near enough meat on your legs to push the pedal down hard enough. Air is much easier to open a valve to the desired amount for braking. Also as previously mentioned the safety benefit of the brakes automatically applying in the event of loss of air pressure.