Somebody

[MalahatTwo7]

Refresh my memory of air brake systems, particularly regarding slack adjuster adjustments.

I just finished reviewing the handouts for my EVOC training (class is tonight) and one of them indicates that "to ensure proper adjustment, the appropriate amount of movement for the slack adjuster should be approximately 1 1/2 inches." This handout does not specify if these are manual or automatic slack adjusters.

After a quick few minutes in Ask.com, a search reveals that manual slack adjusters should not have more than 1/2 inch of play - which I agree with. However I am sure that automatic adjusters need 1 1/2 inches. I can find no substantiation for this.

The main point I am trying to make is that our books do not describe the system in detail, and therefore no descriptors for identifying if a vehicle is equipped with manual or automatic systems. For a new driver I think these are very valid and important points.

To drive any air equipped vehicle, British Columbia requires that the driver be trained and certified for air brakes. I hold that certification, which is where my concern comes from. Could anyone from Virginia give me some insight here? I want to make sure I'm going to bark up the right tree, before I dig a huge hole for myself in class tonight. Thanks.

[pvfire424]

27, the travel is dependant upon the chamber 9 size of) rahter then the adjuster. ( for instance: the adjustment limit on a type 30 chamber is 2")

This should not change whether or not you have an automatic adjuster. If you do have an automatic and you are experiencing too long a stroke, then the adjuster would need to be tested and/or replaced.

The criteria is based upon CVSA ( Commercial Vehicle Safety Alliance) North American Uniform Vehicle inspection Criteria.

Hope this helps

[MalahatTwo7]

Mmmm not sure if that helps or not. I made a note for myself to check my books when I get home. I am sure there is a difference between manual adjusters and automatics, but I like to be certain of my facts before stepping into the fire. :o

I have the number to my a/b instructor from Victoria - at home. Might just give him a call when I get in - just to be sure.

[lvwrench]

I don't know for sure if the items still exist but when Rockwell was Rockwell before Arvin Meritor they had a book on their slack adjusters and a set of plastic or cardboard templates to measure the appropriate distances for their manual and automatic slack adjusters. You might try a search and see if these itmes are still available since I found them quite handy. Chamber size and type of adjuster do make a difference.

[MalahatTwo7]

I haven't heard of that before LV, but have no doubt there might have been such a thing. I did manage to find my air brake training manual and re-read through my EVOC training package. Apprently I had to read a bit slower on what the Co has determined is appropriate for brake adjustment checks. It takes two people to do a "proper brake check" because one is in the cab, and the other is underneath the truck. The purpose is to OBSERVE the amount of travel for the slack adjuster when the brakes are fully applied. Which in this case is 1 1/2" of travel.

I don't know about anyone else, but to me that is both a waste of time, and more importantly an unnecessary risk to personnel. When I was trained to operate an air system, I was taught to do the brake checks on my own. Truck engine off, wheels chocked, parking brake released. Crawl under, using the Brake Buddy, pry on the adjuster. Any more than 3/4" of travel, adjust it down. Anything less than 1/4", open it up a bit. Do the same for all wheels.

I asked my instructor about state a/b certifications, and he looked at me like I just grew a 3rd head. Because we are operating emergency vehicles, the requirement (if there is one for the state) has been waived. Our books talk about making brake adjustments, and also state that any accident that results from a mechanical fault is first the responsiblity of the driver.

My contention is that if the driver is not properly trained to check the brakes on his rig, then how can he be held accountable? The answer to that is the driver is still responsible, because it up to him to know all there is about the safe operation and typical driver maintenance of that vehicle.

Now I may be in the midst of stepping on some really big toes and feet, but ... well at least when the time comes, I know what is required and do carry a certification on my civil licence that says I know how to make the appropriate inspection, and adjustments as needed.