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06-08-2010, 02:24 PM
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#1
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Moderator
Join Date: Feb 2007
Location: NUNYA
Posts: 4,236
Year: 1995
Coachwork: Thomas
Chassis: 3800
Engine: DT408, AT545
Rated Cap: 23 500 gvw
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Re: Air Brake Questions
Go to your DMV and pick up a commercial driver handbook and study the air brake section. With air brakes, you have to understand the system or you might end up without brakes.
CA Commercial handbook
http://www.dmv.ca.gov/pubs/cdl_htm/toc.htm
Air Brake Section
http://www.dmv.ca.gov/pubs/cdl_htm/sec5.htm#sec5
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06-08-2010, 04:00 PM
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#2
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Moderator
Join Date: Feb 2007
Location: NUNYA
Posts: 4,236
Year: 1995
Coachwork: Thomas
Chassis: 3800
Engine: DT408, AT545
Rated Cap: 23 500 gvw
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Re: Air Brake Questions
Quote:
Originally Posted by cincinnati_kid
Quote:
Originally Posted by crazycal
Go to your DMV and pick up a commercial driver handbook and study the air brake section. With air brakes, you have to understand the system or you might end up without brakes.
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At least he wont hurt anyone when the brakes go out
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I don't get it.
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06-08-2010, 05:34 PM
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#3
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Bus Nut
Join Date: May 2010
Location: Texas
Posts: 471
Year: 1988
Coachwork: Ward
Chassis: Ford B600
Engine: 6.6L Turbo Diesel
Rated Cap: 26
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Re: Air Brake Questions
Quote:
Originally Posted by crazycal
Quote:
Originally Posted by cincinnati_kid
Quote:
Originally Posted by crazycal
Go to your DMV and pick up a commercial driver handbook and study the air brake section. With air brakes, you have to understand the system or you might end up without brakes.
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At least he wont hurt anyone when the brakes go out
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I don't get it.
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Air brakes have a spring assembly that engages when the air pressure is too low. Thus, the bus will not move if the air system fails or leaks. So when CK said "At least he wont hurt anyone when the brakes go out", that statement is true.
__________________
We few, we Band of Brothers. For he who sheds his blood with me shall be my brother.
- William Shakespeare ("King Henry V")
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06-08-2010, 05:37 PM
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#4
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Moderator
Join Date: Feb 2007
Location: NUNYA
Posts: 4,236
Year: 1995
Coachwork: Thomas
Chassis: 3800
Engine: DT408, AT545
Rated Cap: 23 500 gvw
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Re: Air Brake Questions
I think there is more to air brakes than whether or not you have air but yes, if you have no air, you're not going very far.
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06-08-2010, 07:16 PM
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#5
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Bus Geek
Join Date: Feb 2006
Location: Saint James, MN
Posts: 2,669
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Re: Air Brake Questions
They are going to "feel" different, but the only way to get used to the lack of a solid connection between your foot and the drums or the delay in their action is to drive them. You'll also be surprised at their power.
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06-08-2010, 07:21 PM
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#6
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Bus Nut
Join Date: May 2010
Location: Texas
Posts: 471
Year: 1988
Coachwork: Ward
Chassis: Ford B600
Engine: 6.6L Turbo Diesel
Rated Cap: 26
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Re: Air Brake Questions
Quote:
Originally Posted by crazycal
I think there is more to air brakes than whether or not you have air but yes, if you have no air, you're not going very far.
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I was trying to simplify the answer. Perhaps I made it too simple. CC you are right. Air Brakes are a complex system. However, in keeping the system immobilized, the answer is simple......
__________________
We few, we Band of Brothers. For he who sheds his blood with me shall be my brother.
- William Shakespeare ("King Henry V")
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06-08-2010, 09:08 PM
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#7
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Moderator
Join Date: Feb 2007
Location: NUNYA
Posts: 4,236
Year: 1995
Coachwork: Thomas
Chassis: 3800
Engine: DT408, AT545
Rated Cap: 23 500 gvw
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Re: Air Brake Questions
One example is not bleeding your brakes and if you live where it freezes, you now have to worry about that moisture freezing in your lines. I am not pretending to be an expert, but it's not just a go, no-go type of thing.
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06-08-2010, 09:45 PM
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#8
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Bus Crazy
Join Date: May 2007
Location: Whidbey Island, WA.
Posts: 1,109
Year: 1984
Coachwork: Blue Bird
Chassis: All American
Engine: 3208 na boat anchor
Rated Cap: 2
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Re: Air Brake Questions
Best to know about slack adjusters and how to adjust (if you don't have the automatic ones.) If the throw on them are past tolerance even your spring brakes won't stop you.
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06-09-2010, 06:26 AM
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#9
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Bus Nut
Join Date: May 2010
Location: Texas
Posts: 471
Year: 1988
Coachwork: Ward
Chassis: Ford B600
Engine: 6.6L Turbo Diesel
Rated Cap: 26
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Re: Air Brake Questions
Quote:
Originally Posted by bus-bro
Best to know about slack adjusters and how to adjust (if you don't have the automatic ones.) If the throw on them are past tolerance even your spring brakes won't stop you.
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Very valid point. The mechanical slack adjusters are easy to adjust. Simply adjust the adjuster to a firm (not tight) contact between pad and drum, then back off 1/4 turn. Also, CC, in cold climates use rubbing alcohol to free up the frozen lines. Alcohol dries up the water and frees up the internal workings of the brakes.
There are air driers that can be grafted into the system to help eliminate water issues.
__________________
We few, we Band of Brothers. For he who sheds his blood with me shall be my brother.
- William Shakespeare ("King Henry V")
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06-09-2010, 07:54 AM
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#10
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Moderator
Join Date: Feb 2007
Location: NUNYA
Posts: 4,236
Year: 1995
Coachwork: Thomas
Chassis: 3800
Engine: DT408, AT545
Rated Cap: 23 500 gvw
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Re: Air Brake Questions
Quote:
Originally Posted by M1031
Quote:
Originally Posted by bus-bro
Best to know about slack adjusters and how to adjust (if you don't have the automatic ones.) If the throw on them are past tolerance even your spring brakes won't stop you.
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Very valid point. The mechanical slack adjusters are easy to adjust. Simply adjust the adjuster to a firm (not tight) contact between pad and drum, then back off 1/4 turn. Also, CC, in cold climates use rubbing alcohol to free up the frozen lines. Alcohol dries up the water and frees up the internal workings of the brakes.
There are air driers that can be grafted into the system to help eliminate water issues.
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I don't live where it freezes, but I know about alcohol. It's not me that is looking for the education, the OP is. All I did was post links to the CA commercial driver handbook and the air brake section. If CK thinks ignorance of air brake systems is no big deal, it's no skin off my back.
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06-09-2010, 06:28 PM
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#11
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Bus Nut
Join Date: May 2010
Location: Texas
Posts: 471
Year: 1988
Coachwork: Ward
Chassis: Ford B600
Engine: 6.6L Turbo Diesel
Rated Cap: 26
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Re: Air Brake Questions
Sorry CC, I was trying to help with four hours of sleep just before beginning classes this mo(u)rning (sometimes I spell morning with the "u" when I'd rather be asleep).
__________________
We few, we Band of Brothers. For he who sheds his blood with me shall be my brother.
- William Shakespeare ("King Henry V")
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06-09-2010, 07:18 PM
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#12
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Moderator
Join Date: Feb 2007
Location: NUNYA
Posts: 4,236
Year: 1995
Coachwork: Thomas
Chassis: 3800
Engine: DT408, AT545
Rated Cap: 23 500 gvw
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Re: Air Brake Questions
Quote:
Originally Posted by M1031
Sorry CC, I was trying to help with four hours of sleep just before beginning classes this mo(u)rning (sometimes I spell morning with the "u" when I'd rather be asleep).
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No need to apologize. I am baffled that people take safety so lightly. Whether that happens to be air brakes or towing a bus with a F150 and some half-wit daydreaming behind the wheel of the bus. Someone asked about air brakes and I post a link to a commercial driver handbook. I guess my mistake was adding my $0.02 that one should understand the system or one might not have brakes.
Maybe someone should ask Smitty if he would like to be on the receiving end of a 20k pound school bus without proper functioning brakes. How about some reckless fool towing a bus knowing what he is doing is illegal and putting other peoples lives in danger.
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06-09-2010, 10:32 PM
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#13
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Moderator
Join Date: Feb 2007
Location: NUNYA
Posts: 4,236
Year: 1995
Coachwork: Thomas
Chassis: 3800
Engine: DT408, AT545
Rated Cap: 23 500 gvw
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Re: Air Brake Questions
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06-10-2010, 12:36 PM
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#14
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Moderator
Join Date: Feb 2007
Location: NUNYA
Posts: 4,236
Year: 1995
Coachwork: Thomas
Chassis: 3800
Engine: DT408, AT545
Rated Cap: 23 500 gvw
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Re: Air Brake Questions
Sorry, I guess I was having a crappy day.
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07-11-2010, 03:18 PM
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#15
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Bus Nut
Join Date: Oct 2009
Location: Idaho
Posts: 575
Coachwork: Thomas
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Re: Air Brake Questions
On topic but slightly not OP ... How expensive are air brakes to fix? What is the big deal with them--why them over hydraulics? Seems like so many things can go wrong while driving with this complex system.
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07-11-2010, 08:13 PM
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#16
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Bus Crazy
Join Date: May 2007
Location: Whidbey Island, WA.
Posts: 1,109
Year: 1984
Coachwork: Blue Bird
Chassis: All American
Engine: 3208 na boat anchor
Rated Cap: 2
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Re: Air Brake Questions
You've got an air compressor, when it starts to go you'll get oil pumped into the wet tank. Drain tanks. Water can freeze in the system when cold. Drain tanks, install dryer, or know how to add alcahol (there is a little tank on those systems). And know how to adust your slack adjusters (unless of the automatic style). If the slacks are beyond thier throw the air diaprams can't apply full force to the brake shoes=no stop! Search Bendix air brakes, it's all there.
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10-11-2010, 09:57 PM
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#17
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Bus Nut
Join Date: Sep 2010
Location: Ocala, FL
Posts: 635
Year: 1995
Coachwork: Bookmobile body by Farber
Chassis: International 3800
Engine: Navistar DT466/Alison MT643
Rated Cap: 1
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Re: Air Brake Questions
The reason that almost all commercial trucks use air brakes is because the brake system can be easily connected to a trailer and thus operate the trailer brakes with the same system. Connecting a hydraulic brake system to a trailer is impossible to do if you want to be able to quickly disconnect and reconnect the supply lines. When connecting air lines to the trailer you are allowed to leak a little (or a lot) of air and it will simply build up again when the on-board air compressor refills the air tanks. Trucks (like buses) that don't usually pull a trailer do not need this capability, so they can use air brakes or hydraulic brakes. As was mentioned before, hydraulic brakes don't have the tendency to freeze in cold climates, so that's a benefit for drivers in high latitudes. Air brakes have the benefit of fail-safe springs, although I doubt you'd want to trust your life to that system by neglecting proper preventive maintenance.
I'm no expert, and I may be way off. This is just stuff I've read online. Since I found it on the internet, I assume it's all true.
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