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dansawyer · 02-13-2022, 05:01 PM

The vehicle is a 2002 National Tradewinds. I am doing general maintenance and have worked to inspecting the rear spring brake mechanism. The brake actuators themselves are relatively clean. However the arms are covered in a coat of oil/sludge. I have identified the connecting mechanism and a separate mechanism from the top. I believe this second mechanism is part of the slack adjuster.

The brake system is working properly. It does not cycle excessively and it holds pressure. At this point I do not believe the oil/sludge is associated with the air system.

Is there fluid / oil in the slack adjuster mechanism? Is it a reasonable trail to follow to look for the oil to be coming from the slack adjuster?

twinboat · 02-13-2022, 06:13 PM

Slack adjusters have grease fitting that need to be serviced along with the S cam shafts tubes.
There is no oil, just chassis grease.

I have extensive experience with air brakes but I'm not following what your describing.

Maybe post some pictures or download a graphic of rear air brake assemblies so you can use the proper names for the parts.

dansawyer · 02-13-2022, 07:51 PM

This is not a great picture, however it shows the actuation arm and the mechanism that appears to be leaking. The photo was rotated during load.

DiplomatDon · 02-13-2022, 08:50 PM

Quote:

Originally Posted by dansawyer

This is not a great picture, however it shows the actuation arm and the mechanism that appears to be leaking. The photo was rotated during load.

You are right it is not a good picture. Try taking it from the side not the back end. In my 43 years of checking and adjusting brakes haven't seen that type of crud build up.

Dutch Star Don · 02-13-2022, 08:53 PM

Make sure that what you're seeing is not grease /oil being thrown on there from the drive shaft, rear trans seal or rear end seal.

Skip426 · 02-13-2022, 09:52 PM

To stop pictures from rotating during posting ; resize to 1000 pixels , or the site computer system does weird things with them .

Judging by the rust on your air system compressor ; in another post ; a previous owner my have coated the mechanism to prevent it seizing up .
Clean the mechanism and monitor for more build up, at your next service..

twinboat · 02-14-2022, 04:36 AM

Here is a picture of what I think your posting.

The booted section is the self adjusters mechanism. If the clevis moves to far off 90° it strokes the rod to re-adjust the slack adjuster.

As mentioned, look for oil being thrown from somewhere else getting on the slack adjuster.

Click image for larger version

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Bruce Anthon · 02-14-2022, 10:51 AM

The slack adjuster has a grease fitting as well as the S cam tube that runs from the slack adjuster to the wheel. Excess grease (or oil from the grease) can run down from there causing what see in your photo. I would grease all the fittings, wipe up any excess and continue to watch. Many semi’s have a adjusters that look like yours over time.

dansawyer · 02-14-2022, 11:00 AM

I have taken better photos. There is nothing near by throwing grease/oil on the adjusters. Is there a lubrication connection from the axle to the adjusters? Or is the only lubrication from the grease zirk?
is there a grease zirk associated with the rotating arm used to apply the brake? If there is this could simply be a case of excessive grease.
I checked the front adjusters, they have a small coating that is directly attributable to grease.

twinboat · 02-14-2022, 11:36 AM

There is a fitting closer to the tire that may have been over greased but no harm if it came out the side near the slack adjusters.

Spray some grease cutter and then water on the parts to clean them up.

There is gear oil in the wheel hub lubrcating the bearings but if leaking will be in the drums and on the brake shoes.

Argosy · 02-14-2022, 01:00 PM

What's on the slack adjuster looks like normal buildup if it was never wiped down. The zerk should be wiped before greasing and any grease pushed out should be cleaned up.

I'd clean the grease up behind the slack adjuster and see if the zerk on the shaft for the S cam is taking grease. It could be it's hard to get on or frozen, but it looks like a lot of grease never made it where it's supposed to be and was never cleaned up.