Adjusting Brakes

I never have adjusted them on any newer truck or trailer that has automatic slack adjusters...although I've pulled a few trailers that needed them adjusted. I figure that, if TA can't touch 'em, I can't either.

 

So here's part one of the article KW refers to (with added emphasis in bold):

NTSB: Don’t manually adjust automatic slack adjusters
By eTrucker Staff
Published March, 09 2006
The National Transportation Safety Board has issued a warning that manually adjusting automatic slack adjusters is dangerous.

The board recommended Feb. 15 that the Federal Motor Carrier Safety Administration develop with the Commercial Vehicle Safety Alliance a North American Standard Inspection training materials module against this practice.

The FMCSA will work with the board to learn how often manual readjustment occurs and to keep this from happening, said Ian Grossman, FMCSA communications director.

“The agency has considered ways to deter manually adjusting automatic slack adjusters, but there is no information that indicates it is a widespread practice – though we do recognize that some drivers and mechanics do it,” Grossman said.

These adjusters are required on certain air-braked vehicles manufactured on or after Oct. 20, 1994. Motor carriers must ensure that the devices are properly maintained, Grossman added.

Manually adjusting automatic slack adjusters should be done only during installation or for an emergency move to a repair facility, the NTSB said.

Manual adjustment “fails to address the true reason why the brakes are not maintaining adjustment, giving the operator a false sense of security about the effectiveness of the brakes, which are likely to go out of adjustment again soon,” the NTSB said.

This practice also can cause abnormal wear to the internal adjusting mechanism, which can lead to brake failure, the board said.

 

Here's part two (divided by me, arbitrarily, sort of, for readability):

The board also advocated that drivers of air braked commercial vehicles weighing less than 26,000 pounds undergo training and testing to demonstrate proficiency with such vehicles.

The board’s recommendations stem from a Feb. 7 report on a 2003 accident in Glen Rock, Pa,. involving a 1995 Ford dump truck on a steep two-lane residential street.

The driver for Blossom Valley Farms was unable to stop at an intersection where four passenger cars were stopped. The truck pushed one vehicle into the intersection, and the car in turn hit three children on a sidewalk. One vehicle driver and an 11-year-old passenger were killed.

The board said the accident’s cause was the lack of oversight by Blossom, which resulted in an untrained driver improperly operating an overloaded, air-braked vehicle with inadequately maintained brakes.

The 21-year-old driver had worked for Blossom less than two weeks. He had never driven an air-braked vehicle before joining the company and had received no training on how to drive one, the board said. Also, the rear truck brakes were out of adjustment, the board said.

Moreover, mechanics misdiagnosed the truck’s brake problems, the board said. Having readily available and accurate information about automatic slack adjusters and stronger warnings against manual adjustment would have helped, the board said.

The accident was similar to a California truck accident the same year in which mechanics did not look for underlying problems with the slack adjusters or other brake components, the NTSB noted.

 

And lastly:

The board also recommended:

• Every state and the District of Columbia should incorporate the information on automatic slack adjusters from the new American Association of Motor Vehicle Administrators model Commercial Driver License Manual into their CDL manuals, which should include an additional statement on the dangers of manual adjustment.
• Manufacturers of vehicles with air brakes and of automatic slack adjusters should include a warning.
• Warnings should be included by the National Institute for Automotive Service Excellence (in its T4 brake certification testing materials) and the National Institute for Automotive Service Excellence (in its certification test study guides).

Well, I know that the mechanics where I work routinely adjust automatic slack adjusters and not just on installation or for emergency. I know it. And we've talked about certifying all drivers on adjusting their brakes. It sounds, though, like we'll trade our 7/16 sockets for tape measures for the most part. Once I get under the truck and adjust the brakes, I get out of my now dirty clothes and usually don't crawl back under.

So KW claims that if the adjuster measures more than 2" or so, the truck is just as OOS as if the low air warning didn't come on. Oh, what to do, what to do... my world is crumbling and I think I'm gonna melt.

I think KW has me caught on the horns of a Cajun dilemma. Drats!! After all the trouble I went to looking for a single deep 7/16 socket not in a set! Grumble, grumble, grumble,, grumble, grumble, grumble, grumble, grumble, grumble, grumble... and trade that for what? A carpenter's FatMax 16' measuring tape??

Humph! Ugh!

 

Whoa Victor,
Careful with that 2" measurement. Maybe you know already, but that's not slack/free play. That means 2" total travel on the brake pushrod, measured by making a mark on the pushrod at a reference point on the brake chamber's face or bracket while the brakes are fully released, then apply the brakes and make a new mark the same way. The difference will be the total stroke. It should be no more than 2", for most brake chamber types.

A slack adjuster's slack is different, in being allowed a max of 1", measured with brakes released, by pulling on the slack adjuster. Some are tough to pull by hand, so I use a short piece of steel bar inserted in the slot by the clevis pin, as leverage.

That article was one of the older ones I had bookmarked, but there are many newer documents issued by FMCSA, DOT, & NTSB (along with the brake manufacturers). I was too whooped last night to scan thru those docs to find them.

BTW, I wanted to address the last lines you wrote in Post #49:
Just so you and others know...
I am not trying to claim any "superiority" over anyone. Not my style, especially in person.
No "final bows" are due, warranted, and definitely not desired.
My rewards come when someone teaches me something, or I teach them something. That's the real motive of "me".
But I am overly persistent, when it comes to trying to show persistent opposing ppl new views.

I guess I come off or came off as asche-whole with "apparent superior knowledge"(as you put it).
I'm not "above" anyone here & never thought I was. Quite the contrary & not even close.
I can show you many posts where I acknowledged & thanked other drivers, who taught me something new, or something I had not realized.
If I was the "superior type" that would NOT have happened.

But now I'm glad you have a great sense of humor about it (I do too), as it shows in your last post.
I give you credit for enduring our head butting over this topic, but mostly for taking time to "look into it" with an open mind.
It truly isn't settled or "won" by anyone. Not me, for sure.

 

Any time I get anew trailer I go under it, and any time i would slip seat I would def go under. I dotn trust the last idiot that drove it

 

Auto slack adjusters can need to be adjusted sometimes. Not sure where this myth came from (the manufacturers?) I was trained by my garage on how to do it, and when I questioned even doing it in the first place they laughed, because they hear it all the time. "We'll let you in on a little secret......."

 

if you have to adjust brakes. you learn as to how easy the bolt turns. and how hard it gets once the brake hits the drum.

you learn not to go that hard. you learn when to stop turning the wrench.

and if you pay attention and watch EVERYTHING as you adjust. you will learn to spot bad parts.

i once pulled a trailer with a bad cam bushing. the brakes were recently replace. why didn't the mechanics spot it? had another trailer with a bracket starting to crack. had a brake can replaced on a truck by company mechanics. but the nuts were gone.

when you climb under neath to adjust your brakes. you spot things that are wrong. becuase if it's bad. it'll move once the brake hits the drum.

your not just crawling under with a wrench. your looking for ANYTHING else that may also be a problem. automatics go out all the time. doesn't mean anything else is wrong. but things do wear out. and they are very easily spotted when you have to turn a wrench.

good solid components don't shift around. worn out components do. and you'll know what your breaks are doing. every time you hit the pedal. worn out components will move till they can't move any more. before your brakes start to move.

when you adjust the brakes. it's opposite. your brakes will adjust till they can't move anymore. then you see the worn out components shift.

one company i once worked for. would check your brake adjustment before leaving the yard. if was the drivers responsibility to adjust his brakes.EVERY DAY. not the mechanics. if you didn't adjust your brakes. and tried to leave the yard. you got written up once. terminated the second time. if a worn bushing or something was spotted. you got turned around back to shop for repairs. and quite possibly went back home. making no money for that day.

 

KW, I like and prefer 'superior' knowledge where ever I find it and I thought you brought it and didn't want to just roll over and sink without a few bubbles bubbling up. I don't have any problem with your persistence. in fact, thanks. It was my sideways fashion to say 'thanks'.

Now, the time I'm spending on TTR--that's a problem.