Brake Test with Ultrashift

I drove an ultrashift for a couple months when I first started teams (they suck by the way) and like someone else said you have to chock the wheels or do the test on a flat surface. I "borrowed" a chock from the O.C. the thing about not turning the truck of unless its in neutral is true we did it a few times and couldn't get her started but eventuality were able to start her up again after messing with the gears a few minutes except for once when we had to get towed luckily the O.C. was only a few miles away. After that we had it with the auto and demanded a manual transmission.

 

Well... the leakage rage you don't pump down. Like I said, the part where he was asking about the pumping the brakes, not hit and hold.

NO and NO (to the first sentence). There is no difference between removing the red emergency line or pumping the brakes down, two different ways to get the same result.

I think you misunderstood me. I said your buttons will pop at the same pressures whether you pump down or pull the emergency line with the brakes released.

Its a personal thing. I do a tug test when I first hook up, then when i test the trailer brakes (and if they work) it also acts as an additional check of your fifth wheel to make sure its locked.

 

jgremlin did not mention pumping the brakes. Jakecat 22 was the first to mention pumping, then you did. Note my response concerned what jgremlin stated, not you or anyone else.

No there is not any difference but neither tests the tractor protection valve which is what you stated they both did. Iin fact it shows a lack of knowledge of what a t/p valve is for and what it does. By doing it either way you stated you are checking that the emergency brakes on the trailer automatically apply, but not the T/P valve. I'll explain more at the bottom.

And I am saying that they should not pop at the same time/same pressure in fact there is no regulatory requirement for the park brake button to ever pop. It should because the mfg designed it to do so, but it's not required to do so. In fact several years ago (1997) the CVSA issued a safety bulletin (97-1) (Google it) to it's member jurisdictions to cease testing the trip on the park brake button and to quit putting trucks out of service because of failure of the yellow button to pop. This bulletin has been superseded and I do not know the bulletin number offhand.

I guess we all have our own way of guaranteeing the trailer will not fall off.

As promised, but I will need to add a disclaimer and a warning. For those who have not taken their CDL permit tests do not read any further.

Sections 5 and 6 in the CDL driver's manual imo are written more for a matter of jumping through the hoops than actually learning anything about air brakes for both straight trucks and combination vehicles. So I will explain the T/P valve and how to test it.

First of all the red button is not the tractor protection valve and it's popping is not indicative of whether the tractor protection valve is functional or not. The T/P valve is usually mounted under the left rear of the cab or sleeper and is usually the valve where the two trailer air lines originate.

When you supply air to a trailer with the red button it sends air through the T/P valve to the trailer and it opens the T/P valve allowing service air to the trailer when a brake application is made. Conversely when the trailer air supply is closed (Red button usually out) the T/P valve should be closed thereby not allowing service air through the T/P valve.

Just because the trailer supply valve is closed (Red button usually out) does not necessarily mean the T/P valve is closed which is why we test it. The test given in section 6 (And reference made to it in section 5) of the CDL manual is not a valid T/P valve test and is more a matter of having students jump through another hoop rather than learn something.

CVSA:

Standard CVSA Roadside Inspection/Test Procedure

When conducting a roadside inspection, the officer will confirm that the Towing Vehicle Protection System is functioning properly in the event of a trailer separation. Testing of the Towing Vehicle Protection System is done under pressure with the engine off and shall be conducted as follows: (TSV refers to the trailer supply valve and a TPV refers to the tractor protection valve.)

1. The system must be within its normal operating pressure range (i.e. between compressor cut-out and cutin.).

2. Wheels must be chocked and all brakes must be released (all dash valves pushed in).

3. Explain to the driver that the supply/emergency and the service/control gladhand couplings must be removed to simulate a trailer breakaway event and to determine compliance of the Towing Vehicle Protection System under this condition. Always have the driver perform this step and make sure to advise the driver to be careful and to take protective action to avoid injury from the high-pressure air, water, oil, or dirt that could escape from the supply/emergency gladhand coupling upon separation.

4. Air will immediately escape from the supply/emergency gladhand line. Listen for and ensure that the air stops escaping from the supply/emergency gladhand line. In most cases the air will stop almost
immediately. In some systems the air will escape for a period of time and then stop, but in no case should the valve fail to close once gauge pressure drops to 20 psi (138 kPa) in either the primary or secondary
system. When the valve fails to close before pressure drops below 20 psi (138 kPa), the power unit is defective. This vehicle has a violation* that is an OOS condition.

5. When the gladhand couplings are disconnected, the trailer emergency (spring) brakes must also apply automatically. Failure to do so indicates that the breakaway system on the trailer is defective. The trailer
has a violation* that is an OOS condition.

6. When the gladhand couplings are disconnected, the trailer system must close automatically. Check the supply/emergency gladhand coupler on the trailer for air bleeding back. Air leaking from the gladhand coupling on the trailer indicates that the trailer spring brake control valve is defective. The trailer has a violation* but it is not an OOS condition.

7. Once the air has stopped and you have checked the pressure, have the driver return to the cab of the truck and instruct the driver to apply the service brakes and hold it.

8. Check for any air escaping from either the supply/emergency or the service/control gladhand line. When air escapes from either gladhand line, the Towing Vehicle Protection System is defective. This vehicle has
a violation* that is an OOS condition.

9. Once the test has been completed instruct the driver to reconnect the gladhands

http://www.cvsa.org/programs/documents/nas/2010-01 Tractor Protection Systems Revised 05-19-10.pdf

Note that at no time did it state the park brake (yellow button should pop out).

The CDL manual is a good manual for a couple of bucks, but it is very lacking concerning air brakes.

 

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