I have a Freightliner chassis under my WB Journey and am taking it in for the yearly oil/fuel filter change/lube and service.  In looking over the manual, it calls for the brake "S Cams" to be lubricated.

I know this is not the air brake slack adjusters, is this something that is contained inside the brake drums?  Do the wheels and drums have to be removed to service the cams or can this be done from outside the rear of the drums?  What happens if you skip this?

Just want to get a handle on this so I can talk knowledgably (sp?) to the service advisor and not get ripped off at $110/hour labor rates.

Best regards! 

Paul,

I believe you're referring to the grease zerk at each of the brake camshafts.
Here is a link to the Frieghtliner doc Knowing Your Chassis
http://www.freightlinerchassis.com/pdf/mh/KnowingYourChassis.pdf

thats a large PDF file, when it opens, go to page 13 to see a graphic and list of all the chassis lube points. The one you're asking about is listed there as item No 7.
No need to remove the drums, its right next the the slack adjusters, just a typical grease zerk to pump some lube into.

Jim

Jim,

Thanks for the info.  As I look at the guide, I don't see any "S" cam mentioned, yet in the Fruitliner Owner's Manual, it does list an "S" cam lube requirement as well as the slack adjusters. 

Guess I'll have to quiz the FL service manager about this.

Also, how do you tell if you have a Meritor differential, the maint. list shows a fluid drain and replacement requirement if that is what your chassis is equiped with?

Thanks again and Best Regards!

Paul,

For FCC unit specific questions like that, you have 2 options:

1) call 1-800-FTL-HELP and give them the last 6 digits of your VIN and they can look it up
or
2) apply for online access at http://www.accessfreightliner.com/  once they authorize your username/password logon info, you can use their "PartsPro" application and the same last 6 digits of your VIN to lookup all your chassis parts and chassis drawings.

Jim

The s cams are what makes your brake linings go against the drum at the end of the shaft that your slack adjusters are on you will find what looks a little bit like a s there is a bearing that should have a grease fitting on it that the shaft goes though. As you apply air the shaft rotates and the s turns and goes against rollers that are fitted into your brake shoes and then applies the pressure to the drum. Hope this helped a little and doesn't confuse.

Old Snipe,

By all means, ask about lubing the S cams, but especially if you're taking the Coach to good service facility, the S cams should be just a normal lube point that is included in the lubrication of the chassis. No wheel or drum removal required.

Wish I had a quarter for evey one I lubed through the years.

Jim

Niles and Jim01, Thank you for enlightening me, I do understand what you've both told me. You can be sure I'll crawl under my MH after I get it back and ensure there is some fresh grease on the S-cam fittings. I appreciate your help, as always, this is a GREAT forum! Best Regards!

Snipe:

The "S" cam is located inside the brake drum.  It is the device that actually spreads the brake shoes apart so that they make contact with the drum.  They are driven by a shaft that passes through the backing plate and is turned by the brake actuator.  Since the cam itself is located inside the drum, it should not be lubricated as any thing you might put on it could make its way onto the surface of the brake shoes reducing their capability to stop the coach.  I am certain that any lubrication of the "S" cams would mean lubrication of the shafts that turn the cam.  A better explanation of this is easily found on the internet by doing a search on "air brakes."

JMO

ahoweth has it right on - as usual...

What is really getting lubed is the shaft connecting the air chamber actuator rod to the actual s-cam like ahoweth said. Here's a diagram. There are typically 2 zerk fittings on this connecting rod. You can see them in this diagram as well. It is just part of a normal chassis lube as should a check of the slack adjustment - even if you have auto adjusters. 

A chassis lube is a simple job but, even with a pit (I don't have one) it is exceptionally dirty crawling around down there and wiping grease/dirt off of everything and poking your nose all around. There are a couple tricks for the DIY like some u-joints have 2 zerks, but the chassis zerks, unlike so many other things on our rigs, are exactly where you would expect them to be every time. I do my own lubes as I can then do a very thorough cleaning/inspection of everything going on down there in the hopes of catching stuff before it is a problem... It has paid off several times for me already. I suspect that most chassis shops will do only a cursory inspection - hence my DIY approach.

Alan and Jeff, Thanks for your explainations, I understand exactly what I need to have done. Jeff, the diagram was great! That really makes me at ease. I want to ensure that my MH has the best care I can give it. Preventive Maintenance was a big part of my early Coast Guard career and I never had a beakdown that left me stranding and walking for help (actually, I would have had to SWIM for help). Best Regards!

Snipe: Lubricating the actuator rods is a very important part of a lube job on any vehicle with air brakes. They all operate essentially the same way. All semi trucks today have the same type of brakes on them, even though ABS has been added lately, it doesn't alter the basic means of actuating the brakes. Consequently any quality shop which does truck maintenance should be lubricating these areas. Of course you would only know for certain if you did it yourself. But since so many thousands of miles are being driven today by trucks with air brakes, I doubt that a shop that cuts this corner would stay in business very long. JMO