J Walker
Oakton, Va
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Joined: 06/12/2003
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I just talked with Freightliner and learned that my Meritor air brakes have an S-cam roller that should be lubricated every year or so. This is a simple task made hard by the work required to get to the part. The tire must be removed, brake drum removed, and the brake shoes removed in order to reach the S-cam. The maintenance manual I got with my 2000 MH did not mention S-cam lubrication but Freightliner's new manual which also applies to my MH in this case has lubrication yearly. The description of the part is that there is a cam which is contacted by a roller. The roller sometimes fails to roll and so it slides. The effect is for the brakes to go bang when making a hard stop. Yep I have had that symptom periodically since the MH was new. This maintenance item is a new one to me and I am a little discouraged since it is not a DIY task and will cost about $400-500 to have a shop do the work. Freightliner customer service says that if the roller slides too much the surface becomes flattened and the repair would be expensive.
Finally, my question is what are others doing to maintain their S-cams? Maybe some air brakes don't have the S-cams. This maintenance item seems excessive!
Jim Walker
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Don36G
New Hampshire
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Joined: 10/19/2006
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I brought my MH in for my state inspection at freightliner and I mentioned to the service manager that I would get a clunk when braking every now and then. He told me all I needed was a shot of penetrating oil on the s cams. They gave each one a blast, and the noise was gone!
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dons2346
Sioux Falls, SD, formerly of So. CA
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Joined: 11/21/2001
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I think all air brake systems have the S cam. Mine is out in the open so it isn't hard to reach.
If I were you, I would be looking at a way to remove the existing zerk and install a hose of some sort to bring the lube point to a point where I could reach it and install azerk there.
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Rollincool
Always Rollin
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Joined: 08/10/2007
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J Walker wrote:I just talked with Freightliner and learned that my Meritor air brakes have an S-cam roller that should be lubricated every year or so. This is a simple task made hard by the work required to get to the part. The tire must be removed, brake drum removed, and the brake shoes removed in order to reach the S-cam. The maintenance manual I got with my 2000 MH did not mention S-cam lubrication but Freightliner's new manual which also applies to my MH in this case has lubrication yearly. The description of the part is that there is a cam which is contacted by a roller. The roller sometimes fails to roll and so it slides. The effect is for the brakes to go bang when making a hard stop. Yep I have had that symptom periodically since the MH was new. This maintenance item is a new one to me and I am a little discouraged since it is not a DIY task and will cost about $400-500 to have a shop do the work. Freightliner customer service says that if the roller slides too much the surface becomes flattened and the repair would be expensive.
Finally, my question is what are others doing to maintain their S-cams? Maybe some air brakes don't have the S-cams. This maintenance item seems excessive!
Jim-
Have you ever worked on BIG brakes before? (I only ask because of some of your remarks in your post.) This isn't as easy as it may seem. (If you think it is.) I would definetely leave this task up to the heavy vehicle mechanics. Jacking up your MH, taking the tires off, pulling the drums and so forth is HEAVY and dangerous work.  If you never worked on these type of heavy brakes before, I wouldn't.
But just incase you have, and you know whats going on, THIS PDF manual will help out a lot. Page 30 Fig 5.23
Good Luck,
-Joe
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wagonmaster2
northcentral oklahoma
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Joined: 02/18/2005
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I have a 2004 coach on a Freightliner chassis. Can anyone explain exactly where the S-Cam is, what it looks like, etc. It would be nice to see a picture but I know how hard that would be from the sound of the above posts. I don't have any brake noise and have been greasing all zerks under the coach but don't know if the S - Cam is someplace else. Thanks for any help.
Wagonmaster2
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JUrban
Delaware
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The S cam is on the end of the actuating arm that moves to apply your brakes. The PDF file that Rollincool referenced shows what has to be done on page 36. The tires and brake drums do have to be removed, but I've been lubing them on my former Bounder and the Tuffin and have never removed the shoes. It is heavy and dirty work but nothing beyond someone who would be able to remove and replace a tire. There is no way you should try to lube the roll pins with a zirk, as it doesn't work that way. Squirting some stuff in on them from the rear may quiet them till you get around the corner. But it will probably get lubricant on the shoes and drums with predictable results.
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toolttime
Morinville Ab Canada
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There is no way you would have to take the wheels and drums off to lube a s cam. The grease fitting on the round tube comming out of the backing plate is what lubes it the s cam shaft is inside. The only time you would ever have to remove the whells and hubs is you were repairing a seiezed or over cammed brake. Also overgreasing is just as bad as no grease at all. Over gresing will contaminate the brake shoes from exess grease leaking by the s cam I have a feightliner chassis in my coach and it has the grease zerks. I have been in the petroleum truck tanking bus and with 4 Peterbilts and . for 31 years freightliner in my fleet I have repaired many over the years.
07 Mandalay
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J Walker
Oakton, Va
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Thanks to Joe for the PDF that shows the S-cam rollers. It shows me where they are and why they cannot be lubed with a zerk. I would never consider doing a roller lube myself due to the difficult and heavy task of removing wheels. The brake shoes may be a bit easier to remove. When I referred to the lube of S-cams being easy I meant after all the work of getting to them was done. For me the lube of S-cams is one that I will find a shop I trust and then decide how often I will have it done. I would like to know how often to lube the S-cam and how many don't lube it at all. Unknowingly I didn't lube mine for seven years and 55,000 miles. All of your posts have been very helpful.
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1fastdad
mo.
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Joined: 08/27/2007
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I have worked on big OTR trucks for the last 30 years and I have only seen a problem with brake rollers a couple of times. The banging problem you discribe is normally cause by lack of lube on the shaft. The shaft hanges up and when it gets enough pressure it comes loose and bangs when the brakes hit the drums. A lot of the OTR trailers you see on the road don't have backing plates on them and are exposed to the wheather and don't have any roller problems. I go along with toolttime and keep oil and lube away from brake shoes.
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wagonmaster2
northcentral oklahoma
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Joined: 02/18/2005
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I keep the shaft with the zerk well greased, I think, but can it be over greased? Is it possible for excess grease from the shaft to get into the drum and onto the brake shoes? I went to the web link above but it didn't indicate how to tell when enough is enough. No problems at this time but always trying to anticipate them, especially since the diesel world is new to me in the last 4 years.
Wagonmaster2
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