| Author |
Message |
Jesse Williams (Buffalo_76)
Registered Member
Username: Buffalo_76
Post Number: 10
Registered: 8-2006
Posted From: 205.175.225.5
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, August 14, 2006 - 11:58 pm: | |
This may seem like a dumb question, but as a newby to busin and especially air suspension and brakes hopefully you'll forgive my ignorance. On the air gauge in the dash of my 4905 there are two needles, one white and one green. What do these needles tell me? The white one comes up pretty fast as the compressor builds pressure but the green needle stays low for a while but eventually come up to 120psi.
Thanks,
JW |
james dean boggs (Jd_boggs)
Registered Member
Username: Jd_boggs
Post Number: 100
Registered: 11-2004
Posted From: 68.70.70.253
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, August 15, 2006 - 2:26 am: | |
These gauges represent air preasure for primary and secondary air tanks for the brakes. It may have a note on the gauge "DO NOT OPERATE BELOW 80 PSI". Before driving your bus pump the brakes 8-10 times make sure the dial is above 80 PSI before taking off. |
Bob greenwood (Bob_greenwood)
Registered Member
Username: Bob_greenwood
Post Number: 87
Registered: 7-2006
Posted From: 65.150.47.248
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, August 15, 2006 - 8:16 am: | |
what ?? |
Jesse Williams (Buffalo_76)
Registered Member
Username: Buffalo_76
Post Number: 11
Registered: 8-2006
Posted From: 74.229.105.27
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, August 15, 2006 - 8:53 am: | |
Where are these air tanks located? There is a tank above the chassis batteries (behind the right front wheel) with two drains coming out of it. Thats the one I drain when I shutdown and park. Is this two tanks in one? Any idea why the green needle stays low for so long?
JW |
Alex Alexander (Doctor_al)
Registered Member
Username: Doctor_al
Post Number: 1
Registered: 8-2006
Posted From: 67.142.130.25
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, August 15, 2006 - 12:44 pm: | |
there is an air tank in the compartment lower left front of bus below the drivers seat. and another in front of the rear axle, about center. most people neglect the rear one because it's so hard to get at. |
mike merrill (Mikemerrill71yahoocom)
Registered Member
Username: Mikemerrill71yahoocom
Post Number: 16
Registered: 8-2005
Posted From: 70.161.78.188
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, August 15, 2006 - 12:48 pm: | |
JW the tank you are talking about is your main tank,you have two other tanks one on the left front under the driver open that comp and you will see it as it has a drain and should also be drained,the other tank is underneath in front of the rear axel which also has a drain,the reason the white needle comes up faster is because it reads the main tank which fills to about 85psi before your aux will start to fill which is why you will notice that your suspension will not come up untill you get to about 85psi,hope this helps Mike 79 h8h-649 |
Jesse Williams (Buffalo_76)
Registered Member
Username: Buffalo_76
Post Number: 12
Registered: 8-2006
Posted From: 205.175.225.5
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, August 15, 2006 - 4:28 pm: | |
Thanks to everyone for the info. I have seen the front and rear tanks but wasn't sure what they were. This whole air-brake/suspension thing is new to me and I'm sure I'll have more questions. I appreciate everyone's patience while I learn. Any more info about the "air" stuff will be greatly appreciated. I have a pretty extensive mechanical background but it's all in aircraft (A&P mechanic) which use compressed air for a lot of things but not suspension or stopping!!! Please keep the info coming.
Thanks again,
JW |
Bob greenwood (Bob_greenwood)
Registered Member
Username: Bob_greenwood
Post Number: 91
Registered: 7-2006
Posted From: 65.150.44.201
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, August 15, 2006 - 4:35 pm: | |
they make a lanyard that replaces the little valves you are unscrewing,run that lanyard to a convienient place & all you have to do is pull on it at the end of the day,if you don't keep the tanks drained,LESS air is in there, tanks will RUST-----truck supply |
Buswarrior (Buswarrior)
Registered Member
Username: Buswarrior
Post Number: 869
Registered: 12-2000
Posted From: 67.68.35.35
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, August 15, 2006 - 8:46 pm: | |
Hello Jesse.
Your bus, being a 1976, should have a dual brake system. Does your build plate indicate any exemption under any permit number for the air brakes?
You want to know at what pressures the other parts of the air system are supposed to be protected from the brake tanks, and then figure out if the various pressure protection valves and regulators that are plumbed in are actually doing their jobs properly. Much of the "real" plumbing in a bus is not included in any driver oriented training materials, and many mechanics are not educated in the engineering involved in air brake system design.
It would cause me some concern if the air system does not "air up" all together. I would want to know exactly why not, and then compare that to what it is supposed to do. I am very suspicious of a dual circuit brake system that does not show the gauges airing up together.
It probably isn't best to refer to any part of a dual air brake system as the "main" part. All parts of the air system are important, and serve their various purposes. We need to use the proper terminology so as to not confuse ourselves.
Bob's advice to retrofit cable drains in your tanks is a good one! Makes the job easy, and when it is easy, it gets done!
I have been lazy, and not done that yet to mine. Gotta find some time!
happy coaching!
buswarrior |
Richard Bowyer (Drivingmisslazy)
Registered Member
Username: Drivingmisslazy
Post Number: 1656
Registered: 1-2001
Posted From: 75.108.82.163
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, August 15, 2006 - 9:50 pm: | |
If I understand it correctly, on my Eagle the main tank aired up first to about 60-70 lbs and this is the tank that the brakes work from and that guage always came up first. The second guage, for the auxiliary tank that fed such things as the W/S wipers always came up later after the main tank was up to where there was enough air to operate the brakes.
Richard |
David Evans (Dmd)
Registered Member
Username: Dmd
Post Number: 68
Registered: 10-2004
Posted From: 71.125.20.202
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, August 15, 2006 - 10:17 pm: | |
Jesse, on the main page you will see down on the left The Coach Builders Bulletin. Click on and find the books George Meyers sells. His latest is all you would ever want to know about air and brake systems on buses. His bimonthly bulletin is not a fancy magazine but has more usfull info than the others. Pretty good stuff, its compilations of his articles for Bus Conversion Mag. |