Help! How Is Anyone Supposed To 'accurately" Read An Air Pressure Gauge Like This One?

Soulin H.

OK This what the book says for Commifornia:

1. Governor Cut-out Test After safety starting your engine, push in your tractor and trailer brakes. Pick one gauge (primary or secondary) and stick to that gauge for the "Whole Air Brake Tests". Governor Cut-out Test, (Engine Running), Should cut-out No More than 140 psi .(While engine is running),

Use gas pedal to build up air to normal pressure (not more than 1500 Rpm) Once both needles on Primary & Secondary gauges stop moving, release the gas pedal. **Call out the needle readings on the gauge you have picked** If it is good, Then tell the DMV tester "This is a good Test"

2. Applied Leakage Test (Engine Shut Off)

Should Not Leak more than 4 psi in 60 Seconds in a combination Vehicle such as this Tractor and Trailer. Once both needles on Primary & Secondary Gauges have Settled, Push and hold brake pedal, once needles have settled again call out needle readings on gauge you have picked, then your 60 seconds starts. STILL HOLDING THE BRAKE PEDAL. After 60 seconds is up, release the brake pedal first, then give out the reading on the gauge you have picked. If it is good, "This is a Good Test"

3. Governor Cut-In Test(Engine Running)

Should Cut-In in no less than 100 psi **After Applied Leakage Test , Build Air Pressure to Cut-Out Pressure before you perform this test** * Push and release the brake pedal only once. * Call out needle reading on gauge you have picked. * Push on Gas Pedal and hold for 10-15 Seconds While watching the needle movements. * If needle doesn't move, repeat the above step 3 again.

Once the needle starts to move call out the gauge reading from that needle movement point.

"This is a Good Test"

4. Low Air Warning Light & Buzzer Test, (Engine Running)

Light and Buzzer Should Turn On Between 55-75 PSI

After the Governor Cut-In Test is completed, keep using the brake pedal till the needles drop in the range and turn on the light and buzzer.

* Make sure it is a consistent Light and Buzzer * Call out the reading on the gauge! * "This is a Good Test"

5. Spring Pop Test (Engine Shut Off)

Springs should pop Between 20 & 45 PSi

After you have Shut Off the engine:

* Start Pumping the brake pedal till Both Valves(Red and Yellow) Pop Out. * Once both Red and Yellow valves pop out, STOP PUMPING THE BRAKE PEDAL. * Call out the gauge reading. (Example 30 PSI). "This is a Good Test"

Then the Tractor and Trailer Tug Test And the Service Brake Test

When you are done the examiner will tell you that you either passed or not.

NOW THIS IS FOR COMMIEFORNIA AND WEST SACRAMENTO to be exact.

I do believe that some examination stations might have a different set up.

REMEMBER, the pre-trip has to be done first. This whole process takes about 2 hours.

Hope this helps you.

1 Re:

You are not being tested on whether you not you can read the gauge,

Actually the instructors at my school have said to me and other students otherwise. They would disagree with that statement.

Re:

Soulin, aside from my mistake, you were given the correct answer.

Yes Old School, I realize most of the answers here have been correct. I was not referring to your so humbly admitted incorrect answer.

Re:

You just can't let it get the best of you in this job. Very few things are perfectly accurate in this career. You will discover that no two trucks air compression systems act identically....

... Try to relax and not drive yourself crazy by overthinking the details. This probably sounds unprofessional to you now, but about three years into this career you'll understand me. Of course, if you think I'm crazy now, and continue stressing over the minutiae, you'll never last three years in this job. It will drive you nuts.

Thanks Old School; your points well taken, I understand. Even though I am as of yet inexperienced in the trade, I do agree with that and have life's experience with many other things that same advise; would be wise to take for sure.

I have been reading posts on this website for a couple of years now and have been absorbing the informative info that is so graciously given by so many here. It is one of the things that weighed-in for my decision to follow through and get my Class A CDL.

Re:

Your on a forum full of people who have already passed this test and your going to claim we can't help you with "Thanks for trying....But no cigar"??????

Plan B, 1- My humble apology for appearing to be smug and ungrateful with my mannerism regarding the "no cigar" comment. 2- I very much acknowledge your honest good advice. I do appreciate the photo of the gauge and your support and mention that my situation is not in the least bit unique.

Re:

Step one is simply checking for leaks. Your holding the brake down while listening for leaks and making sure the pressure does not continue to drop while you are doing so.

That test is called the "Applied Leakage" test and is for the "Service Brakes" (according to CA Manual and my instructors.) In in my school that would be step 3 but most probably could be step 1. That is just not the way I am being instructed here.

At the DMV the wording we use must be accurate. I have already have shown where by using the literal verbatim of what the CA DMV refers to as the "Static Leakage Test" as. It is for the parking and emergency brake systems which must not loose more than 3 psi after the air pressure gauges "stabilize" and in exactly 1 minute (using the tractor towing a single trailer with air brake system that we have to test in at DMV anyway.

Re:

Mr/Mrs Evaluator I am going to pump down on the brake pedal until the warning light and buzzer come on at or before 60psi."

Here we have to be 100% accurate with what the minimum and maximum (range) where the "low Air Pressure Warning" light and/or buzzer come/s on. The range here in CA is a minimum of 55 psi and a maximum of 75 psi. That being said, on the trucks that we practice on in the yard and the test truck, yes the low air pressure warning system initiates at ~ 60 psi.

BTW, FWIW, I am now quite (and have been for a few weeks now) familiar with the "Spring Brake Pop-Out" test... ...(minimum 20 psi and maximum of 45 psi... ...Also, FWIW, all of the air brake test pressure ranges and steps. I was just asking here if anyone would have a specific way to read the gauge I posted a photo of, not much more other than asking why anyone would make such a gauge like that (with intervals of 30 psi instead of 10 psi) in the first place.

Re:

Yeah, this guy is gonna be a real treat to deal with. Wait until he gets on the road one-on-one isolated with his first mentor. He's gonna give one or two smartass remarks like that and on the second day find himself sitting on the side of the road hitching a ride.....with no cigar.

OK Brett. I think you may be exaggerating just a wee bit on that 'second day on the road' comment. I did not realize that some would take it that way regarding my no cigar comment gee wiz!

Now I think no matter what way I explain the why I said (meant) that contextually some here would likely say that I am making excuse for what you have decided is a "smartass' remark. I just assume get back on track of the topic instead of getting so offtrack about differing ways that the 'no cigar' comment was supposedly intended by me to contextually mean... ...OK it was a smartass remark.

I will I will do my best and hopefully will not be making any more 'smartass-like comments here.

That being said, I do appreciate the wealth of information on this website and hope that I can contribute in some way in the future, or maybe something that I already asked and the answers that were or will be generated in the future have been or will be helpful to someone anyway.

BTW, FWIW, Re:

Yeah, this guy is gonna be a real treat to deal with. Wait until he gets on the road one-on-one isolated with his first mentor. He's gonna give one or two smartass remarks like that and on the second day find himself sitting on the side of the road hitching a ride..

Not going to happen.

Thanks (Raptor) You did miss one though.. ...Not meaning to be a "smrtass"... ...just saying:

Check Rate of Air Pressure Buildup To perform this test, the engine must be running at normal operating idle, typically 600–900 rpms. Observe the air gauge to determine if the pressure builds at the proper rate. For dual air systems, the pressure should build from approximately 85 to 100 psi within 45 seconds.

1 Re:

You are not being tested on whether or not you can read the gauge,

Actually the instructors at my school have said to me and other students otherwise. They would disagree with that statement.

Might want to ask for a refresher on the gauge reading course then, because this gauge reading is inaccurate.

1/2 way between 90 and 120 is 115 for example,

1/2 way between 90 and 120 is 115 for example

Might want to ask for a refresher on the gauge reading course then, because this gauge reading is inaccurate.

Oh man......that's some unfortunate math right there! No wonder you're unhappy about this gauge.

Thanks for trying.......but no cigar.

I'll just go with

As for reading gauges, here are my gauges. The first is with the key in the on position. The second is with the key off.

The top is the one for applied break pressure. The bottom is for air system pressure.

This is going to sound like a dumb question, but this is the first time I have seen primary and secondary air on the same gauge. How does one determine whether it's showing the reading for the primary or secondary?

This is going to sound like a dumb question, but this is the first time I have seen primary and secondary air on the same gauge. How does one determine whether it's showing the reading for the primary or secondary?

There are two needles on the gauge. Orange needle is primary and there is a green needle underneath the orange one that is your secondary.

Ahh! Gotcha! Looking closer I see the shade of green on the side there. *Home Simpson "DOH!!!" moment*

Thanks!!!