Trucking DIY Brake Adjustments

I agree drivers who can go years on a brake job and use jakes all the time do not adjust as well as the drivers who are on the brakes all the time

 

Article
Don't Let Poor Brake Adjustment Catch You Unawares
Brake adjustment is a pain, but it doesn’t have to be if you use stroke indicators.
April 2013, TruckingInfo.com - WebXclusive

by Jim Park, Equipment Editor - Also by this author


Constant Adjustment
Slack adjusters, as the name implies, are designed to take up the slack in the stroke as friction surfaces wear away. In “normal” service in a U.S. highway environment, a manual slack adjuster might need adjustment every 10,000 miles or so, says Dale Holman, president of TruckWatch Services in Georgetown, Ontario.

“But there’s no such thing as normal when you’re talking truck brakes, and that’s why slack adjusters are designed to be adjusted. You make the adjustment when it’s required, not because some mileage interval has come and gone. It’s not like an oil change.”

Manual slack adjusters require operator intervention, and could get close to the adjustment limit in a short time under certain conditions. Automatic slack adjusters do an admirable job overall of keeping stroke within limits, but a lot of auto slacks are found to be out of adjustment during roadside brake inspections. With manual slacks, improper adjustment is often a matter of negligence or laziness on the part of the operator, but when auto slacks go out of adjustment, there’s usually something else going on.

If you take nothing else away from this piece, remember this: Automatic slack adjusters normally don’t require manual readjustment. If you have a brake that is over-stroking and it has an automatic slack adjuster, you have a problem with either the brake or the adjuster. If you readjust it, you aren’t really fixing the problem. A manual readjustment may bring the brake back into compliance and improve the way the brake operates, but it will only be temporary.

Faulty auto slacks can be a factor, Holman says, but that’s rare. “If there is a mechanical issue, it’s more likely to be improper initial installation, or faulty or worn components elsewhere in the brake system.

“But in my experience, the primary cause of auto slacks stroking beyond their limit, is – believe it or not – good drivers,” he says. “I’m talking about the driver who never makes an application harder than 15 or 20 psi because he or she never has to. They’re the ones who manage speed well, keep a safe distance, and coast up to traffic lights. These drivers hardly ever put enough torque through the adjuster to cause the ratchet to roll over to the next peg. Consequently, as the brakes wear naturally, the auto slacks aren’t compensating.”

What these drivers need to do is make half a dozen full pressure applications once a week or so to get the adjuster to turn over, and then visually check the stroke before leaving the yard.


Looks like one thing we can agree on is automatic slackers maintained properly will adjust their self.
Snowmanw900, I don't do the back up deal but I know some guys that back up fast and hit the brakes hard in the north to free up ice, maybe that where the other OP is mixing up info.

 

I'm just guessing but, hard brake application in reverse was/is the way drum brakes adjusted themselves on cars.

 

Right, on cars/pickups. True.

Drum breaks with cams, no.

im still wondering why he thought reverse would have anything to do on that.

 

Brake shoes are anchored solid to the spider on heavy trucks. Direction makes zero difference as to how they will adjust. Cars/light trucks are typically only anchored loosely at the top and free float with a star wheel link at the bottom. Braking in reverse causes the shoe to self energize/servo and triggers the adjusting arm, expanding the star wheel link.

 

I use my jakes, plan my stops/speed changes ahead of time, and rarely apply more than 25-30psi of brake pressure to stop so I have to manually adjust my brakes from time to time.

ETA. a set of brakes usually lasts me 300-325k while driving mostly 2 lane roads so they dont' get much of a workout.

 

Every time you set your parking brake thats equivalent to a 65-70 psi brake app.

I do that prob 20 times a day.
You guys are over thinking this.
If working correctly they dont need adjusting.

 

Right!!!