How do you adjust the trailer brakes?

Large wheel chocks in front & back of wheels are better than using a curb. Something like a piece of 4x4 lumber is good. Just remember your braking ability is reduced. Get that fixed.

 

The size of the adjustment nut, the standard slack adjuster is 9/16, automatic 7/16. And the automatic are bulky looking.

 

https://youtube.com/shorts/_k0M9ypjLI8

 

I missed the "red valve pulled out". My mistake & i also stated the wrong wrench size. Correct size is 7/16th. I usually used a crescent wrench.

 

I’ve never used a crescent wrench, don’t want it to slip. I’ve only used a Boxed wrench.

 

Holy crap there is some misinformation on here...
There is little to nothing on the road that still has manual slack adjuster, they have been outlawed for many many years I'm pretty sure.
Air pressure does not apply the brakes when you pull the red knob. it's a heavy spring that applies the park brake. those can break or just get weak.
Automatic slack adjusters don't normally require adjustment, if they do there's a good chance they are shot.
Mr expedite_it id recommended watching some YouTube videos. it's very easy to adjust brakes but I video visual might be helpful to you.

 

Misinformation ? I did say/mentioned “IF” the automatic slack adjuster “ISNT” working. I’ve ran across quite of few that don’t work properly and had to do my own adjustment. And have written them up for the shop, but when your on the road, you got to what you got to do. I didn’t read about the red valve. I know when I need to slide my tandems, I use the rolling motion then lay on the trailer hand valve(trolly) or whatever they call it now.

 

You don't need a video

Just look at the brakes.

If they don't hold with the valve pulled. They're out of adjustment. But that's all 4 tires. If one or more are actually working. You won't know. Until you get under there and look.

You don't need measuring tools. A good adjustment will have the brake practically kissing the drum. A bad adjustment will show a gap.

It's not rocket science.

Release the brakes and look under there. For any gaps between brake and drum.

The brakes need to be released anyways to adjust them. However. You need one vehicle applied. If you're adjusting the trailer. Leave the truck applied. If you're adjusting the truck. Leave the trailer applied.

You shouldn't need to chock unless both vehicles are bad. Or you're unhooked. And dealing with truck only.

7/16 and 9/16 are most common. I don't know how manuals are outlawed as some of us to this day still see them.

Occasionally you'll run into the square adjuster. 5/16 or 8mm is needed for those. My last job had them. My current rig has them on the drop axles.

I adjust to snug and back 3 clicks. I like a tight brake adjustment so I don't have to adjust them as often. Once a week is preferable to daily. But that's local work. Highway driving isn't as bad.

If they're not adjusting. They're bad. And should be replaced. Adjusting them at least keeps them braking better. But Occasionally you'll run into completely froze up..at which case. Immediate replacing is called for or you'll be oos and a scar on your psp.

Backing up and slamming on the brakes is a waste of time and hard on the equipment. If They're not working like they're supposed to going forward. They won't work backing up.

I watched a truck in Montana do that. You could see the gaps on his trailer. After backing a few times. He left. The gaps never changed.

 

I was mostly talking about the 9/16 wrenches and manual slacks. 99.99% of ppl have never and will never see a manual slack.
if its find a slack adjuster out.of adjustment i will grease it and adjust it. if it goes.out.of adjustment again I'll replace it..
many times they quit working just from lack of lubrication