Automatic slack adjusters?

Most tractors I run up to roughly 1994 model year for me was a cutoff. In terms of automatic slack adjusters vs Manual Slack Adjuster. You needed either a 9-16th inch wrench or a half inch wrench and a length of school house chalk to mark your strokes on the rods plus a ruler down to the 16th level of measuring.

When you are told to pull around back and bring all your papers in over pull into your parking spot by about 15 feet. Put her into reverse (With automatic slack adjusters only, not manuals...) move about 3 feet, MASH your service brakes to the floor and hold it. Let it go back up another three feet MASH again your service (foot) brake and hold a few moments. Repeat about 6 times total. BEFORE you bring in your paper work etc. To DOT outside you are just making final parking adjustments, and if that DOT man is any sharp at all mentally, he will understand why you sound like you are totally intent on draining your entire service tank into your brakes while backing up. (You are simultaneously testing your low air alarm in both Primary Tank and Secondary Tank. You are making a adjustment Ghetto style. DOT man is going to crawl in there with something to measure your stroke with. (Gawd, I hate the english language...) and mark each one. During the inspection.

Now here is where you the driver has to leave the automatic slack adjusters the hell alone with your tools. If Memory serves me, there is a sleeve that goes over the bolt that determines stroke length of that specific push rod based on your strict situation at. that. wheel. based on drum wear, pad wear, metal fatique of your stroke rod general over all view of your braking system guts at that level. If everything is in order, Inspector will move on to the next set of automatic slack adjusters.

You, the untrained driver (Im dead serious here... listen to what I am saying and do not pay attention to what I am not doing.) do not make adjustments to automatic slack adjusters manually with tools. You turn that tractor trailer into dealership such as Volvo, Freightliner etc or to your Company Shop and designated TRAINED mechanics will make the adjustments necessary. If they are done right, your tractor trailer will be pretty balanced on braking with a very good effort for maybe 15 pounds application gauge if that. You don't even need that much, 9 or so would be outstanding. Stop like you ran into a wall while empty.

Anyway, Ive said enough. The last thing I want to do is confuse anyone. On the much older iron you dove under that rig and built new brakes by adjusting to less than 1 and 1/16th stroke length I believe. As your pads wear further towards baremetal, your adjustments will increasingly be a failure until you install new pads.

Good luck!

 

If it fails it will get replaced because chances are you're not going to be able to move.

 

The reversing while braking has no effect on brake adjustment. Unless you call tearing the chambers from the axles an adjustment. Never ever attempt that, it's not how they work.

 

Hm. Nice picture. And pretty strong postion too. Even I must concede that point. However... habits die hard. I have not ever.. er... lost a brake due to this method of quickie adjusting. Ive only been formally inspected for stroke length 4 times in my life time So just the behavior trying to be sure that the brakes are somewhere in the vicinity of being adjusted this way is exceedingly rare in my 50 plus years on this planet.

That also should show the sorry state of Federal Based Truck Inspections when I only got probed 4 times in my life time out there at the scalehouses. Im not exactly asking for more frequent inspections mind you. Don't have time for dat what with the appontments and so on.

 

That picture shows a failed weld bracket above the chamber onto what I interpret as the frame. Do you have another perhaps a better angle?

I think due to metal fatique property and physics that brake chamber assembly would have torn loose at some point that it actually went ahead and did as the metal bracket above got tired over time and finally snapped.

 

Putting the truck in reverse has nothing to do with slack adjusters. That is not how they function. It's not an old Chevy caprice. If make 3 or 4 hard stabbing break application (once you're stopped) they will adjust if they are functioning properly. It had nothing to do with backing up!!

 

It's not the reversing, it's the movement in general. With more than 90-100 psi a full stoke on the brake pedal will adjust them. Move forward (or backward) and do it again to ensure everything is good to go. Don't know why but when the adjuster can't seem to adjust moving forward allows it to do it's thing.

 

had one fail on the left side of tractor, it pulled to the right when the brakes were applied, took it a shop via counter steering, they replaced it. there appears to be different levels of fail

 

That sounds more like an abs failure on one wheel than slack adjuster. If you have abs fail on one wheel you have regular brake locking while others are antilocking and can cause you to jacknife.

 

left steer brake can