How do you adjust the trailer brakes?

For the most part. You are correct. If functioning properly they should find correct adjustment.

 

I would say if the number 1 cause and highest percent of oos for trucks nationwide is brakes being out of adjustment spec that autos still do not do their job. They still need to be manually adjusted at least as part of a pm. Manual slacks and an application gauge and proper adjustment will still pass a brake test better than autos will anyday. The backing off 1/4 or 1/2 is just rule of thumb. No slack, cam or clevis pin is the same. One may need to be 1/3 or 3/4 turn to get proper rod stroke measurement.

 

Those that think you have to back up to adjust them must be thinking of the old wedge brakes, but I doubt that many are that old. LOL

 

My 81 Mack training tractor at matlack had wedge brakes and their relationship with those who had to fix 'em...

I remember the Self adjusting Slack adjuster and training certification mandate...

I also remember the warnings as the 'new' self adjusting slacks came on-line.

Warnings NOT to whip out a wrench and DIY to one loose adjuster as some of the 'new' adjusters would break if the wrench holder didn't know how to release/properly adjust them making that brake assembly useless but to report them instead..

That's when the FCMSA decided to grandfather any carrier's mechanics presently trained and working with their brake systems AND allowed individual's [like owner operators] to be 'certified after 'training'.

NJ motor truck assn. presented training classe monthly for years might still do; I don't get the emails now.

 

Oh wow, did you bring back memories, my first truck I drove had wedge brakes, they NEVER worked. It was a short wheelbase cornbinder. Me being green and driving that POS was a nightmare whenever I was bobtailing. IDK how many stop signs and red light intersections I ran thru them. Long story short….. I quit after couple of months.

Edit;
And to adjust them was another project by itself.

 

Just like older auto drum brakes. Kept them lubed up they were fine. Keep all the dust plates on and all DOT could check was by tapping the drum

 

Funny thing about wedge brakes is I can say i’ve never experienced them and actually never known anyone that still had them growing up. Old timers I was raised with talked about them and had them on some trucks but they all said they went to the scrap pile pretty quick for s-cams. I have seen them on trucks at shows or in junk yards plenty of times.

 

This was on a 1973 International Transtar. I will never forget that POS. It belong to an O/O. This was back in 1979 when I had that unfortunate experience. Definitely taught me a lot.

 

I was told with auto slacks you didn’t want to crank them down and then back them off because when you back them off they’re going against the ratchet. That’s why they click and pop when you back them off.

 

In a previous life in the late 70s, I worked for Air Products. They always wanted to be running the latest technologies.
So we had disc brakes on the trucks and wedge brakes on the trailers.

When they refurbished the trailers, you would've thought that was the perfect time to upgrade the outdated brake system.
But they didn't see it that way.
They were a handful in the rain and snow with half a load.