How do you adjust the trailer brakes?

As far brake adjustment, the only proper answer is in the geometry of the rod & slack. They need to be at 90° at full application. On manuals, that was 1/4 turn back from snug. With autos, the pitch of the adjusting thread varies, so on the rare occasion I've had to adjust them, I'll use the drum tone to make sure they're off the drum, and set brakes to verify geometry.

 

Our 2 newest 3 axles chassis have color coded and marked brake rods, very easy to determine proper adjustment and if they are close being out of adjustment. Even had one inspector make a joke about it, that even if he was color blind, he wouldn't be able to flunk my brakes due to the incremental markings.

 

Marking the pushrods with paint is a great ideer. I can't believe they didn't do that years ago.

 

Zip tie works fine

 

If you don't own that trailer and it's not insured by you, and you run over a family of 5 and faulty brakes caused the accident you got trouble. If brakes need adjusting there is more to it than simply turning a nut on an a slack. Self adjusting brakes do not need adjustment when all of its components are in correct spec and in working order. If your asking what tools are needed then you're not qualified to identify the underlying issue of why they are out of service. Every single component that is tied to brake service has numerous possibilities if wear and it damage that needs to be identified. If it's cammed over there is no adjusting until cam or bushings, bearings, drums, shoes, ECT: are replaced. You could inadvertently cause friction contact heating resulting in a wheel seal failure from overheating leading to axle oil/grease pouring onto red hot bearings or hub. Those are the trailers you see roadside burning to the ground before a fire truck gets near it. In some states it's illegal to touch any brake without a training certificate. The load can wait until the owner of that trailer makes repairs. This shouldn't be a topic of conversation if the trailer is inspected and maintained as scheduled and proper pre Tripps are performed.

 

Iirc stand on the brake pedal and 100 psi is supposed to adjust auto slacks, lack of grease kills them more than anything

7/16, 9/16, or 3/8” and a flat head until tight and back off a quarter plus a couple extra clicks is how I do it,

 

The truck stop puts plenty of grease on the brake linings, the fuel water separator, the center link, the tyres, the exhaust, the driveshaft, some on the bottom of the DEF tank. They even get it all over the bottoms of the fuel tanks. But they have yet to hit one single zerk fitting with it. I swear, it's like some magic trick.

 

I don't know if it actually works, I have never tired it and then went to see if there was a difference. But, I have read that brakes can be "calibrated" by releasing the brakes and then pressing and releasing the break pedal a few times. It supposedly will make the auto slack adjuster tighten up. It won't work correctly if the brakes are warm though, from what I read.

When I have seen a mechanic adjust a self adjusting slack adjuster, they do the same as the old days. Tighten it down, then back it off a quarter of a turn.

 

Assuming they even have ASA's, they shouldn't need adjusting and if they do they need a brake inspection by someone that knows brakes. That's safety territory. The training and DOT guidelines are "Do not adjust ASA's". People do, but the right thing to do is find out why they went out of adjustment or aren't adjusting. Manuals, you adjust frequently.

 

This brake is parked. Imagine releasing the valve. And the gap widens. Don't need measuring tools to know it's out of adjustment. Keep your brakes adjusted properly and you don't need to worry about measuring. It'll be well within the 2 inches maximum allowed before oos. Adjusting for a 2 inch stroke is silly.