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Author Topic: Rear Slack adjuster question.....  (Read 2023 times)
NCbob
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« on: June 12, 2006, 06:27:37 AM »

This will prove how little I understand my braking system but recent events have caused me to go to Da Book and I found this interesting tidbit of information (which proves to me that I should definitely attend the Bendix Clinic upcoming).  Shocked

"Be sure that the air pressure is over 60 PSI before adjusting the rear brake Slack Adjusters". Right from the MC5A Maint. Manual.

Why?  To be sure that the parking brake is released?  I thought my brakes were adjusted properly...after all it was done when I picked up the bus and by the previous owner.  I know there was no pressure in the system and probably the parking brakes were applied.  Embarrassed   Seems dumb now but no wonder I'm complaining that I don't have any stopping power.  Tongue

At the time it somewhat surprised me that so little adjustment was necessary.  Undecided

OK guys, jump aboard and straighten me out.  Wink

NCbob
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gumpy
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« Reply #1 on: June 12, 2006, 07:01:26 AM »

You cannot adjust the brakes with the parking brake applied. I'm not sure it's even physically possible to turn the adjusting screw, but it definitely will leave you brakeless on the drive axle if you were successful.

I'm going to recommend that, before you continue driving your bus, that you find someone (another busnut, a truck driver, a qualified mechanic) who will show you (not just tell you) the proper way to adjust the brakes. It's not overly difficult to do, but if you don't know what you're doing (and based on your previous post, I dare say that you don't, or you wouldn't be writing that post), you are putting yourself and everyone on the road near you in grave danger. I'm not trying to bash you here, and I think you understand just how dangerous this is. This is not something anyone should take lightly.

Do attend the Bendix training, if you can (wish I could), but by all means learn how to properly adjust your brakes before you drive that bus again.

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Craig Shepard
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NCbob
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« Reply #2 on: June 12, 2006, 10:21:20 AM »

Thanks Craig, but please recall that the seller thought he was showing me how to adjust the brakes but it's pretty clear to me now that he didn't know much more than me. Right now the bus is in the shop and I'll ask my mechanic to go through the brake adjusting procedure with me while HE's doing it.

I have more than enough white hairs over this brake thing.  One would think that if a guy owned a bus for 15 years HE'd know how to adjust them properly.

The main reason I exposed myself to criticism is that I want to KNOW...not guess.

Thanks for you response.

NCbob
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gumpy
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« Reply #3 on: June 12, 2006, 10:28:38 AM »

Excellent idea. Ask your mechanic to teach you the proper way to adjust all the brakes. Make sure he can show you how to adjust, and how to measure the travel properly.  Note that there will be different measurements for front vs. rear brake assemblies.

Yes, it's scary to think that someone actually owned and drove that bus for 15 years and didn't understand how to adjust the brakes properly, let alone how the emergency brakes work.

I'm glad to hear you are willing to learn and do it properly.

Again, no criticism was intended. Just trying to emphasize how critically important this issue is.

Please let us know how this turns out. And I'd be interesting in hearing a brief description of the technique he teaches you to use.

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Craig Shepard
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« Reply #4 on: June 12, 2006, 11:20:22 AM »



Why?  To be sure that the parking brake is released? 

Basically, yes.  If the air is not up to pressure, the parking brake could be partially set enough to where you thing you are getting a good adjustment, then when you air up, the parking brake releases completely and you have no service brakes.  I think it's unlikely that this would happen, but there is really no way to know that your parking brakes are released unless you are aired up.  I always wait for the dryer to purge and double check that the parking brakes are released before adjusting brakes.  I snug the slack adjusters, then back off 1/4 turn.
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Busted Knuckle
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« Reply #5 on: June 12, 2006, 03:21:51 PM »

First off though be double darn sure to chalk the wheels where it can't roll foward or backard! BK
Smiley Wink Grin Cool We gonna party in West Tennessee! We gonna have a bus Party! Roll Eyes Cool Shocked Grin
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Busted Knuckle aka Bryce Gaston
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JackConrad
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« Reply #6 on: June 12, 2006, 03:40:23 PM »

Also do not get under the bus without blocking it up. Air suspension can make you very flat very quickly.  Jack
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NCbob
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« Reply #7 on: June 12, 2006, 04:05:27 PM »

Oh my yes!  Shocked  I thank each and every one of you for the safety tips.  Grin  I might have been born at night but it wasn't last night!  Wink

The longer I hang around these boards...the more I learn.  I was never one to hang out under any vehicle without first making sure either the hoist or (if on the ground) the wheels were chocked.  I ain't a big guy but I'm sure not looking forward to getting any smaller...or thinner.

I'll keep reading Da Book, it's on the back of the ...well it's in the reading room...and every morning I add a bit more knowledge to the vast stores of ..emptiness. Smiley

Thanks guys,

NCbob
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FloridaCliff
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« Reply #8 on: June 12, 2006, 04:41:41 PM »

Bob,

If you get everything fixed, what are you and Charlie going to do all Winter? Wink

Cliff
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« Reply #9 on: June 12, 2006, 07:45:32 PM »

Remember to check your stroke after adjustment. I have seen stroke measurements reveal problems with foundation components. In my opinion an adjustment without stroke measurement is worthless.
When I adjust mine I'll measure stroke, adjust, and measure stroke again.

Maintenance....it's a beautiful thing. Grin Grin GrinTq
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Torquester
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Sojourner
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« Reply #10 on: June 12, 2006, 07:58:19 PM »

Reason to have at least 60psi or great is keep “Parking” Push-Pull valve in “IN” (release) position to cause “inversion” valve to unload (zero-psi) in parking/emergency chamber while 45 psi or greater at “locking” port to release locking mechanism.

It all explains in first few page of “Brake” department of your MCI manual.

Website to Bendix Brake Chambers Stroll down & look for DD-3 Safety Actuator. Click “Download/View” button & left click on “Service Data Sheet”

http://www.bendix.com/products/ViewLiteratureDownloadMenu.do?key=ActuatingDevices

FWIW

Sojourn for Christ, Jerry
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