Skip to main content ↑ ↓
Topic: seized "S-cams" (Read 2465 times) previous topic - next topic
0 Members and 1 Guest are viewing this topic.

seized "S-cams"

Yahoo Message Number: 20789
Thought I would share with the group that I had a scare recently.
While at the Ft. Myers rally, Jake (tech) was crawling around, looking under my coach for an unrelated matter when he noticed a possible seal leak in the rear wheel. I fortunately already had an appointment at Ken Robertson's in Lakeland, so I added it to the list.
Turns out that (chicken or egg... not sure which came first) The inner seal did indeed fail and the S-cam was in the seized position when they removed the wheel to get to it. Then we discovered grease and oily mess all over the brake and everything-- as well as the brake pad that was down to the rivets! I was informed that worst case scenario I could have been a flaming brochette going down the road, had luck not been with me.

I do have Smartire and I keep an eye on inflation. I never had an alarm go off for temps, but I have been traveling down the East coast since September, so no big grades. I drive conservatively and use my jakes and shifter, effectively. I do not hotrod. Maybe that saved my behind. No I did not notice pulling to one side. Front brakes were excellent. No problems there.

There was no external evidence of a problem and I don't crawl underneath, so I would never have known without being in the good hands of Country Coach techs at the Ft. Myer's rally. Thank you JAKE!
To finish the story. It turned out it was the inner seal and Lester at Robertson's said it looked like a slow drag. FYI the opposite brake shoe was fine and looked hardly worn. But we replaced both of course.

I am still concerned with why the S-cam was seized up. One CC technical person thought it might be that the last time I had it lubed up north, the tech only put a few pumps of grease in it thinking it was enough. Otherwise I have no idea either if the seal failure and oil spray caused it to stick/seize or if the brake seized which blew the seal, but I think the latter is more likely. But what do I know?

SO. I will be watching the temps on all wheels more than usual, keeping an eye on those brakes that way, manually by touch/compare and the smartire temp reading- ESPECIALLY when I am going over the Western passes on my way back to OR/WA this spring.

Can I be rude and say that was a pucker factor of 10 even after the fact? ( I didn't say that...) :-0

By the way, Ken Robertson's is a great service place to keep in mind and I highly recommend them. The experienced techs from Buddy Gregg are there now. I believe Ken was the service mgr for BG before he sold it the first time. You can stay with teh coach and watch everything they do... I did and learned a lot.

Rosemary

2000 Magna #5798

Re: seized "S-cams"

Reply #1 –
Yahoo Message Number: 20793
First of all, what is an "s" cam ?? I assume something to do with the brake actuator (rotates to apply the brakes maybe ???)

Secondly, thanks for the Ken Robertson info ... we live about (5) miles from their place and I have heard good things about them but never been there.

John and Terry
2005 Affinity

Quote from: Rosemary, Magna #5798
>

Thought I would share with the group that I had a scare recently.
While at the Ft. Myers rally, Jake (tech) was crawling around,

looking

Quote
under my coach for an unrelated matter when he noticed a possible

seal

Quote
leak in the rear wheel. I fortunately already had an appointment at > Ken Robertson's in Lakeland, so I added it to the list.

Turns out that (chicken or egg... not sure which came first) The

inner

Quote
seal did indeed fail and the S-cam was in the seized position when > they removed the wheel to get to it. Then we discovered grease and > oily mess all over the brake and everything-- as well as the brake

pad

Quote
that was down to the rivets! I was informed that worst case

scenario

Quote
I could have been a flaming brochette going down the road, had luck > not been with me.

I do have Smartire and I keep an eye on inflation. I never had an > alarm go off for temps, but I have been traveling down the East

coast

Quote
since September, so no big grades. I drive conservatively and use my > jakes and shifter, effectively. I do not hotrod. Maybe that saved

my

Quote
behind. No I did not notice pulling to one side. Front brakes were > excellent. No problems there.

There was no external evidence of a problem and I don't crawl > underneath, so I would never have known without being in the good > hands of Country Coach techs at the Ft. Myer's rally. Thank you

JAKE!

Quote
>

To finish the story. It turned out it was the inner seal and Lester

at

Quote
Robertson's said it looked like a slow drag. FYI the opposite brake > shoe was fine and looked hardly worn. But we replaced both of

course.

Quote
>

I am still concerned with why the S-cam was seized up. One CC > technical person thought it might be that the last time I had it

lubed

Quote
up north, the tech only put a few pumps of grease in it thinking it > was enough. Otherwise I have no idea either if the seal failure and > oil spray caused it to stick/seize or if the brake seized which blew > the seal, but I think the latter is more likely. But what do I

know?

Quote
>

SO. I will be watching the temps on all wheels more than usual, > keeping an eye on those brakes that way, manually by touch/compare

and

Quote
the smartire temp reading- ESPECIALLY when I am going over the

Western

Quote
passes on my way back to OR/WA this spring.
> Can I be rude and say that was a pucker factor of 10 even after the > fact? ( I didn't say that...) :-0 > > By the way, Ken Robertson's is a great service place to keep in mind > and I highly recommend them. The experienced techs from Buddy Gregg > are there now. I believe Ken was the service mgr for BG before he

sold

Re: seized "S-cams"

Reply #2 –
Yahoo Message Number: 20816
Okay, I am not a "gear head" but will make an attempt to explain it.

"S cam" slack adjuster is called that because it is shaped like an "s". It is a self-adjusting( for wear) part of the brake system (along with springs and camshaft etc...) that moves the brake pad into braking position when you actuate the brakes and vice versa. If it seizes up, like it did in my situation, it locks the brake on. If it is "flipped" it will fail to apply the brake.

RE: the seals, just to clarify: There is an inner seal and an outer seal in the rear dual axle which also contains two sets of bearings.
Apparently the outer seal is more easily repaired and if oil is seen on the outside of the wheel, that is your clue that you have an outer seal leak. If the inner seal is leaking, everything has to be removed and it is a very expensive repair. :-(

It is easier to show you than for me to explain. I took pictures of the wheel removed, so I will attempt to upload them to our website. No promises.

Maybe someone can explain it in more accurate technical detail.

You can also see an example in drawings on the Bendix website technical manual on pg.19. Try this link:
http://www.bendix.com/downloads/air_brake_handbook/BW5057_online.pdf
Actually there might be an article on this in an upcoming "Destinations" magazine... no promises there either.

Rosemary

2000 Magna 5798

Re: seized "S-cams"

Reply #3 –
Yahoo Message Number: 20823
Thanks Rosemary ... I never heard of them called that before, but I know what you are referring to.

Thanks for the link also, that a good reference.

Good luck ...

John and Terry
2005 Affinity

Quote from: Rosemary, Magna #5798
>

Okay, I am not a "gear head" but will make an attempt to explain

it.

Quote
>

"S cam" slack adjuster is called that because it is shaped like an > "s". It is a self-adjusting( for wear) part of the brake system

(along

Quote
with springs and camshaft etc...) that moves the brake pad into > braking position when you actuate the brakes and vice versa. If it > seizes up, like it did in my situation, it locks the brake on. If it > is "flipped" it will fail to apply the brake.
> RE: the seals, just to clarify: There is an inner seal and an outer > seal in the rear dual axle which also contains two sets of

bearings.

Quote
Apparently the outer seal is more easily repaired and if oil is seen > on the outside of the wheel, that is your clue that you have an

outer

Quote
seal leak. If the inner seal is leaking, everything has to be

removed

Quote
and it is a very expensive repair. :-( > > It is easier to show you than for me to explain. I took pictures of > the wheel removed, so I will attempt to upload them to our website.

No

Quote
promises.

Maybe someone can explain it in more accurate technical detail.

You can also see an example in drawings on the Bendix website > technical manual on pg.19. Try this link: >
http://www.bendix.com/downloads/air_brake_handbook/BW5057_online.pdf
Quote
>

Actually there might be an article on this in an upcoming > "Destinations" magazine... no promises there either.

Rosemary

2000 Magna 5798

>
 

Re: seized "S-cams"

Reply #4 –
Yahoo Message Number: 20852
I'll try to explain this and still keep it short.
Mounted on each side of your rear axle are the spring brakes (sometimes called parking brakes). Coming out of the spring brakes is a rod that attaches to one end of your automatic slack adjuster.
The other end of slack adjuster is splined and attaches to one end of the "S" cam. The "S" cam runs into the inside of the "hub" and the actual "S" part of the cam resides there. Each end of your brake shoes are configured with a semi circle opening. One end sits on a non moving pivot pin and the other has a roller cam that sits on either the top or bottom of the "S" cam (top brake shoe and bottom brake shoe).

When you push on the brake pedal the rod extends out from the spring brake, turning that slack adjuster, turning the "S" cam and "spreading" the brake shoes causing them to come into contact with the drum. End result is you stop. The "S" cam turns in a counter clockwise direction. There is a "spring kit" that supplies a counter pressure to the brake shoes that pulls them back from the drum when you release pressure on the brake pedal.
When a brake "cams over" it goes past the open end of that "S".
Brakes USUALLY "cam over" because the diameter of the drum and the thickness of the shoes exceed the limit of the "S" cam travel.
In MH application most do not run enough miles to encounter this situation. If you have had this problem I'd be looking at a bad auto slack adjuster. You will need a new set of shoes, spring kit and a new drum. These are not expensive nor difficult parts to replace.
Our brake systems are for the most part very dependable and NOT complicated.

Now for the inner seals issue. Inner seals fail for a multiple of reason, the three most common I suspect are they "dry" out (non use), loose wheel bearings, and dirt contamination. They USUALLY start to seep first before they finally really let loose. You can take a flashlight and look for an accumulation of dust around the inside of the drum/shoes/tire WITHOUT GETTING UNDER THE MH. Once it really starts to leak you will see a "wet" run of oil coming down the inside of the tire. Once brake shoes get contaminated with oil they can be steam cleaned and reused. However as the shoes get hot the impregnated oil will be drawn to the surface of the shoes and diminish braking ability, and if they get hot enough they could start a fire. For the cost of new shoes I would just replace them.

Michael

01' Intrigue #11224

Quote from: Rosemary, Magna #5798
>

Okay, I am not a "gear head" but will make an attempt to explain

it.

Quote
>

"S cam" slack adjuster is called that because it is shaped like an > "s". It is a self-adjusting( for wear) part of the brake system

(along

Quote
with springs and camshaft etc...) that moves the brake pad into > braking position when you actuate the brakes and vice versa. If it > seizes up, like it did in my situation, it locks the brake on. If

it

Quote
is "flipped" it will fail to apply the brake.
> RE: the seals, just to clarify: There is an inner seal and an outer > seal in the rear dual axle which also contains two sets of

bearings.

Quote
Apparently the outer seal is more easily repaired and if oil is

seen

Quote
on the outside of the wheel, that is your clue that you have an

outer

Quote
seal leak. If the inner seal is leaking, everything has to be

removed

Quote
and it is a very expensive repair. :-( > > It is easier to show you than for me to explain. I took pictures of > the wheel removed, so I will attempt to upload them to our

website. No

Quote
promises.

Maybe someone can explain it in more accurate technical detail.

You can also see an example in drawings on the Bendix website > technical manual on pg.19. Try this link: >
http://www.bendix.com/downloads/air_brake_handbook/BW5057_online.pdf