Community Forums

nitedriver57 · 02-20-2022, 06:56 PM

Retired journey level bus mechanic here. If you have no training or limited experience with s-cam, air brakes, and self-adjusting slack adjusters, PLEASE take your RV to a repair shop or call a mobile mechanic to do the repairs. The RV weighs many times what your car or pickup does and you could easily do something wrong and if you are involved in an accident you would be liable for any damages or injuries.

johnmontgome · 02-20-2022, 10:00 PM

Be smart and take that thing to a shop.

Todd727 · 02-20-2022, 10:55 PM

First takeaway for me is that you have not been doing proper pre-trip inspections. You should have caught that slack adjuster issue long before now.

From the answers, it also appears a few others might not be doing a proper pre-trip also.

Grab your states CDL manual and find a good YouTube video on pre-trip, particularity the air brake portion.

Jchemie · 02-21-2022, 08:48 AM

Inspection & maintenance of the air brake system on a regular basis is the best thing you can do. From reading all posts on Dansawyer trying to get it to work, wouldn’t it better to replace the rusted, sticking unit by now? Yeah, it is gonna cost you, but it sounds like the unit is pretty well worn and used up. Time for a new one and a certified air brake mechanic to look over the entire system for other problems. And ask if the mechanic will show you what he is looking for and show you as he/she inspects. Then you will educated to check your own system, just not certified (��). Better safe than sorry.

twinboat · 02-21-2022, 10:09 AM

Quote:

Originally Posted by Jchemie

Inspection & maintenance of the air brake system on a regular basis is the best thing you can do. From reading all posts on Dansawyer trying to get it to work, wouldn’t it better to replace the rusted, sticking unit by now? Yeah, it is gonna cost you, but it sounds like the unit is pretty well worn and used up. Time for a new one and a certified air brake mechanic to look over the entire system for other problems. And ask if the mechanic will show you what he is looking for and show you as he/she inspects. Then you will educated to check your own system, just not certified (��). Better safe than sorry.

If you re-read the OPS posts, you would see that the pin is seized in the slack adjuster and clevis.

The first step to removing either the slack adjuster or the brake chamber is to remove the clevis pin. They don't come as a kit.

He has to and is attempting to free up the seized pin.

Parkers2ca · 02-21-2022, 04:51 PM

Quote:

Originally Posted by dansawyer

I greased the S cam arm and tested the action with the brake released. It was smooth and operated as expected. I then operated the brake as normal and it stuck again. I then slowly levered the arm back into the release position. I noticed a significant scraping sound. It sounded as though the actuator arm threads were binding on the actuator case.

I then inspected the base position of the actuator that is binding and compared it with the gap on the other wheel. The darker image, left shows a greater gap between the cast and the yoke then the lighter image on the right. I am now suspecting the alignment / positioning of the actual actuator.
I am not sure how to proceed from here. It is a bit over the top suspect the actuator, however the differenct in gaps leads me to go there next. I plan to remove the yoke pin to get a reading on exactly where the neutral actuator position is.

Are there other paths to perform first?

Check that clevis pin turns, it could be seized. That is a pivot point and will give symptoms you described. You may have to use a torch and heat it red to get it to turn. If you get it free put a coat of anti-seize on it.

dansawyer · 02-21-2022, 05:24 PM

Thank you all. Yes, as Twinboat observed, the pin was seized on both on the clevis and on the slack adjuster. It is now beginning to move a bit, but it is does not have full range of motion.

The task at hand is to pull the pin. I will try an oxy-acy torch next. I tried butane yesterday but the flame was too broad. I plan to heat the clevis and the adjuster arm and try not to heat the pin. The plan is the holes expand somewhat and the pin size remains fixed.

Once it is moving somewhat freely I will create a simple press to pull it.

To the comments in the thread:

This could have created damage had it not been found; however it was identified relatively early. As was pointed out early in the thread, there is an additional list of areas to check.

RichardE · 02-21-2022, 06:05 PM

When I am using the torch in such a technique to enlarge the hole before enlarging the part in the hole, I use a cutting torch. I just don’t hit the O2 blast. The cutting tip puts out a lot more heat in a concentrated area than a standard welding tip.

mackwrench · 02-21-2022, 06:37 PM

Quote:

Originally Posted by dansawyer

Thank you all. Yes, as Twinboat observed, the pin was seized on both on the clevis and on the slack adjuster. It is now beginning to move a bit, but it is does not have full range of motion.

The task at hand is to pull the pin. I will try an oxy-acy torch next. I tried butane yesterday but the flame was too broad. I plan to heat the clevis and the adjuster arm and try not to heat the pin. The plan is the holes expand somewhat and the pin size remains fixed.

Once it is moving somewhat freely I will create a simple press to pull it.

To the comments in the thread:

This could have created damage had it not been found; however it was identified relatively early. As was pointed out early in the thread, there is an additional list of areas to check.

IF it's starting to move, keep spraying blaster on it and try it every few days, it'll go....

Be careful applying heat for any extended length of time, the rod will transfer heat inside the chamber and damage the rubber diaphragm.

Journey cat · 02-21-2022, 08:28 PM

Use ~ OSPHO ~ use a small paint brush give it a good soaking and it removes rust in a few hours like nothing https://www.amazon.com/SKYCO-Genuine...a-567050222626

Todd727 · 02-22-2022, 12:37 AM

Do you have access to an air hammer/chisel? If so, grind the head off (unless you can get to it from the bottom) and use the air hammer with the punch attachment to drive the pin out. That will put vary little stress on the arm.

dansawyer · 02-22-2022, 09:51 AM

It is starting to rotate, but not without a small assist to get it started.

I have an acetylene torch and an air hammer if it comes to that. I was hoping to loosen it to the point I could 'press' it out. I am trying to be very carefull not to over heat or over force anything.

I can only get free access to the head side of the pin. The cotter pin side only has an inch or so clearance. I am taking a trip out to inspect this AM, I will take something to measure the clearances.

I tried a couple of days ago to rotate the pin with a pipe wrnch. However the teeth simply slid on the collar. I suspect the pin may be hardened.

mlpeloquin · 02-22-2022, 01:16 PM

In my early life, I worked in a vertical motor plant. We did use torches to heat shafts when we had stuck shaft collar. We sometimes needed to add dry ice to the collar all while swinging a 100lb brass hammer on your knees to uncock it. Then light taps to get it off. If heat does not do it, see if you can get dry ice to cool the shaft down after heating. Expand one and shrink the other. You might try Mouse Milk as well.

Rob_M · 02-22-2022, 02:52 PM

Quote:

Originally Posted by mlpeloquin

You might try Mouse Milk as well.

Ok Fauker…. How do you milk a mouse?

Sorry couldn’t pass that one up.

At work sometimes we have to heat and cool pins, shafts, and even bolts multiple times to get them to shrink enough to come out.