Guages

I should have elaborated more and giving a more detailed description of what those gauges are. Reason being, those gauges are pretty important. Others on here are definitely correct, when teaching someone about driving a tractor, having proper air pressure is super important. Considering the fact that if they fall below 60psi your brakes engage. Kind of important when traveling down the Hwy.

 

How did 80% fail the question?

It is a stupid question. One that should never have had to have been asked.

Like was said earlier, if you need to ask this question, you have no business driving a cmv.

Neither of the gauges in the photo are for just the tractor or just the trailer. The same two gauges would be a Class B straight truck that only has a yellow knob.

 

Define irony...

 

The primary tank supplies air to the tractor rear brakes and air operated accessories.
The secondary tank supplies air to the trailer circuit and the steering axle brakes.

 

https://hnctruckparts.com/images/airbrake.jpg

 

But, what if you’ve got a pre-121 single circuit without steer axle brakes? Lol!

 

Maybe your attitude is why no one taught you about those two gauges and how they work in the first place?

 

Everyone was giving you solid information. Not our fault your not grasping the concept. This forum is a great place for information, and I’m very glad that it has the potential to help new drivers such as yourself. But at some point you need to be able to apply that information. Go get em big guy.