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largebus
Advanced Member
USA
468 Posts |
 Posted - 12/05/2002 : 5:30:59 PM
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While I am not a mechanic or technician I was curious about a recent trouble. The arrival of cold weather and harsh winter conditions in Western NY is wreaking havoc on several buses-the new ones only. The air doors are freezing consistently, causing buses to arrive over 15 minutes late for 3 consistent days. What recommendations would any of you have for this air door problem? The buses themselves are running but the doors simply freeze and a bus with two open doors is "broken down". What are your recommendations?
Logan C. Geen
Future Superintendent of Schools |
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Rich
Top Member
United States
5768 Posts |
Posted - 12/05/2002 : 5:41:13 PM
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Just wondering. What bus brand are these buses? I've never heard of this happening, but perhaps it has to do with the high pressure from the cold air? 
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Unwrap the School Bus Within You!
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largebus
Advanced Member
USA
468 Posts |
Posted - 12/05/2002 : 5:50:23 PM
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Most are AmTrans that are maybe 2 or 3 years old at most. However, the 5 new Blue Bird buses that arrived this year (which run like a dream compared to the AmTrans, half of which didn't start when they arrived, and are otherwise nice buses) are also experiencing the same problems.
Logan C. Geen
Future Superintendent of Schools |
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KMM
Advanced Member
USA
271 Posts |
Posted - 12/05/2002 : 6:58:45 PM
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We bought air doors from 97 to 2000 and had problems with most of them in cold weather. All buses purchased from 2001 to present have went back to manual doors in our fleet. I personally never liked air doors to begin with.
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Indy bus mech
New Member
3 Posts |
Posted - 12/06/2002 : 05:40:43 AM
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Check your air system to make sure the air dryer is doing its job. Manuelly drain the air tanks to see if there is moisture in them. We had one of our new Bluebird that froze do to excessive moisture, and found the air dryer was bad.
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PHW
Top Member
USA
1345 Posts |
Posted - 12/06/2002 : 06:46:42 AM
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Try a air gun type lubricant and inject a small amount into the air inlet side of the door engine if applicable.
PHW
Child Check For Life
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LaidlawDriverMassachusetts
Senior Member
USA
160 Posts |
Posted - 12/06/2002 : 10:54:52 PM
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How long have the busses been running in the morning before routes? Maybe they need to be started earlier and put the heaters on an hour in advance to warm the busses. We have a few problems in our yard with this situation. One driver has to get up and open and close her door because the bus was not allowed to warm up enough- so her air door didn't work properly. I've never had a problem with my door - We have two different kind of systems - Some busses have dual air brake systems -
Air Park Brakes with Air Service brakes usually always need to be warmed up for at least a 1/2 hour in the AM or they will experience problems with the door and stop sign-
what i really don't understand is...Busses that have hydrolic service brakes but have air park brakes Never have problems with the doors yet both systems the doors are air operated-?
so my advice would be to allow the bus to be started earlier and warmed up- If you are still having problems maybe the line to where the air travels is broken? THat's happen to a few busses
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bbird66
Top Member
USA
881 Posts |
Posted - 12/07/2002 : 09:16:27 AM
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I'll bet these buses have air brakes also, they are just another problem in the air "loop" get manual opening.. I dont like electric either.
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BusInspector
Active Member
USA
11 Posts |
Posted - 12/08/2002 : 7:58:58 PM
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It sounds like condensation may be getting into the accessory line to the air door system. Many times the manufacturer's plumb the line from the wet tank on the air system instead of through a pressure protection valve plumbed through the front brake side of the air system. You may want to install an old fashioned alcohol dripper system at the compressor or relocate the feed line. I am in upstate NY on the eastern side and have not heard of many problems with air door freezing. I wouldn't get rid of the air doors just yet. Many repetitive wrist injuries have been linked to manual door mechanisms.
DOT Nick |
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Craig Thoricht
Senior Member
USA
177 Posts |
Posted - 12/10/2002 : 03:03:16 AM
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Hello-
I have a small fleet-30 buses-but all have air doors. They can be a strange beast on occasion, but the one thing I have noticed with ours is that the operating pressure usually has to be SLIGHTLY adjusted upward in cold weather.
The previous post about plumbing is correct about the supply line coming out of the wet tank but condensation has not been an issue for us in northeastern Ohio.
Be sure that all pivot points are very lubricated and that the doors are properly hung in the opening. Not that Bluebird would hang a door improperly.
I would be careful about excessive idling time in cold weather. These newer diesels don't generate a lot of heat until they are put to work and Cummins and Caterpillar are vocal about "excess idling" in their owners manuals.
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Churchville Charlie
New Member
United States
8 Posts |
Posted - 12/10/2002 : 08:47:14 AM
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Parts are available from body MAN.We have had air doors since 1984 and have had almost no problems.
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largebus
Advanced Member
USA
468 Posts |
Posted - 12/11/2002 : 6:16:59 PM
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Hey Churchville-Charlie you are literally right next door to me! I attend Spencerport schools, so we are "neighbors". Everyone-thanks for the info I will pass it on to my driver and the garage. Thanks again!
Logan C. Geen
Future Superintendent of Schools |
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BusDiva
Top Member
USA
609 Posts |
Posted - 12/14/2002 : 06:26:33 AM
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Logan
We had that problem a few years back when we got our first round of AmTran RE'S.
We came back from winter break when they arrived and the driver's started buses but no door power.
Not having any information from International and me not reading the owners manual failed to read what things we needed to do in cold climate. Well, the buses left the garage and all called me-(i was dispatcher then) and said none of them could get above 5 mph and still had no door power.
After about 10 minutes of driving they began to call in 1 by 1 and said they did get full door power and their buses were running at normal speed to no problems.
I instantly called our International rep and he explained the follwoing:
In cold climates, the Internatioanl products need to run for a minimum of 10 minutes at an RPM of 1250. This allows the engine to warm up and for cold parts for the door control- located near the outside of the bus to warm up. He said to try it and let him know.
Well, we had temps in the teens the enxt morning, so we started the buses up 30 minutes early, idled them as instructed, and before the drivers pulled out, they all called in saying the doors worked perfect and all the buses ran fine.
We also did the sanme with our thomas Saf-T-Liners we had and also had no problem.
perhaps try this and see what happens.
I am a firm believer in air doors for safety reasons and would never spec a manual door.
It's the little things that count |
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PHW
Top Member
USA
1345 Posts |
Posted - 12/16/2002 : 07:06:50 AM
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A reason for the low power and air doors not working could be the accessory air tank.This tank supplies air to the door and air throttle. When the air tanks first fill up with air the accessory tank is the last to get air. You'll notice when the air guage first builds up it hesitates at about 85 to 90 psi. That's when the accessory tank first starts getting air. When the accessory tank psi catches up with the other tanks they all go up together. If you start driving your bus before the accessory tank gets air you will have no air to the air throttle or air door. This accessory tank does not register on your air guage.
What happens at times is when the bus sits for awhile the accessory tank may bleed down but the other tanks dont. Your air guage will show full even tho your accessory tank may be empty. This is another reason your fast idle, air windsheild wipers, etc.are not working at first until the accessory tank builds up.
PHW
Child Check For Life
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bus tech 151
New Member
USA
9 Posts |
Posted - 12/18/2002 : 4:51:34 PM
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| Your busses are hidding water in the air lines . Check and bleed your air system. We have found injecting about 1qt of alcohol in the air system works well. |
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Brad Barker
Administrator
USA
874 Posts |
Posted - 12/18/2002 : 5:54:47 PM
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Be careful when injecting alcohol into air systems. Once in a while would be OK to relieve an occassional problem but constant use will cause premature problems with air valves. The alcohol washes the lubricant off of seal rings inside the valves causing them to fail or have internal leaks. Bendix does not recommend the use of alcohol in their systems manufactured in the last ten years. Installation of an AD-9 air dryer would be a plus. The easiest fix is to drain air tanks daily. Have your mechanic install a cable pull drain valve on each air tank. They can be purchased for about $5 each. Most buses will have three or four air tanks. So for $15 to $20 bucks you solve your moisture problem.
Brad
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Air Door Troubles
