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Author Topic: Governor  (Read 3436 times)
John316
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« on: October 12, 2008, 06:55:25 PM »

How do you adjust the air governor. We want our air to stay between 115 and 120. It doesn't kick the compressor on soon enough when we are in traffic. It drops to maybe about 100 then the compressor starts and brings it up. I want it to kick the compressor on between 110 and 115 to bring it up to 120 or 125. I know that is a little tight parameters, but in traffic you don't want to get at all low. I just don't know how to adjust the governor. I think that there is two screws on it, but I haven't looked closely yet.

Any suggestions of pointers would be great. I am still learning. Smiley

God bless,

John
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white-eagle
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« Reply #1 on: October 12, 2008, 07:02:23 PM »

i haven't had a problem with my governor and i'd be a little concerned about having my compressor running each time i hit the brake.  i've been in some traffic jams, but no problems or even close.

i'm sure that didn't answer your question, but i think it obviates the need for doing anything.
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« Reply #2 on: October 12, 2008, 07:06:12 PM »

To adjust the D-2 take the cap off the end, free the locking nut and rotate the set screw (I think clockwise) to increase the set PSI - max PSI is 130 PSI +/-    HTH
« Last Edit: October 13, 2008, 07:15:26 AM by niles500 » Logged

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makemineatwostroke
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« Reply #3 on: October 12, 2008, 07:41:29 PM »

John316; what you trying to do can not be done with a governor adjustment if it set at 120lbs it will not kick in till around 105lbs.The only way is take it to a air brake specialist and he can do with the unloaders on the compressor but it won't be cheap     

                                have a great evening
« Last Edit: October 12, 2008, 08:26:39 PM by makemineatwostroke » Logged
buswarrior
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« Reply #4 on: October 12, 2008, 09:24:25 PM »

Your typical air system governor will operate the air system over a 20 to 25 lb spread between compressor cut-out and cut-in.

The numbers you quote sound fine to me, and your air system is functioning normally.

Now, as to what your air consumption rate might be....

Often, those unfamiliar with air brakes use far too much brake pedal, and hence, too much air waste, for a lot of stops. Try to feather back on the pedal and at all times of brake pedal use, you only squeeze down the absolute minimum to get the job done. The amount of pedal used to hold the bus stationary is often the worst waste of air.

Does the system leak? With the air system full, with the parking brake released, and foot on the brake pedal to the floor, turn off the engine and watch the air gauge. If it stays still for one minute, great. If it is dropping, not great, go get those leaks fixed, they all add up to compressor run time, and air not being available for the brakes.

Or, another way, your air system should stay full/within the governor range running down the interstate indefinitely unless there is some air consuming feature operational.

Way too many busnuts have been fooled by someone into thinking air leaks are acceptable. Constant cycling of the compressor shortens its life, and depending on where the air is leaking, and the rest of the air system maintenance, leaks could be dangerous as the brakes could be compromised under the right failure conditions.

Good for you in wanting a good supply of air!

happy coaching!
buswarrior
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BJ
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« Reply #5 on: October 12, 2008, 10:39:31 PM »

 Grin taint nothing wrong with your air system. If it ain't broke don't mess with it  Grin
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Sojourner
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« Reply #6 on: October 12, 2008, 10:53:46 PM »

Read the link about D-2 Governor:
http://www.bendixvrc.com/itemDisplay.asp?documentID=2382

You can change pressure setting but the pressure range between cut-in and cut-out is not adjustable.

FWIW

Sojourn for Christ, Gerald

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Dreamscape
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« Reply #7 on: October 13, 2008, 02:53:07 AM »

Leave it alone! Wink

The more your compressor runs to keep up with such tight settings will just cause more condensation, which is water.

The settings you have are just right, I would suggest not to mess with it!

The following Bendix link is one I found the other day and it has been most helpful.

https://www.bendix.com/EN-US/SERVICE/LIBRARY/Pages/SDSheets.aspx

Everything about Bendix applications that most of us have is there.

By the way, if you have a manual it should describe how do adjust your govenor, mine did.

HTH,

Paul
« Last Edit: October 13, 2008, 03:19:17 AM by Dreamscape » Logged
John316
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« Reply #8 on: October 13, 2008, 09:16:43 AM »

Thanks guys for the input. Yes we do know how to use the air brakes (read books and looked at courses, talked to truckers and busers, and we have gone through all of the DOT book on CDL etc.). That makes sense about the parameters. We haven't had a problem yet, but I didn't want to have any problems with running out of air. We don't have any major air leaks (we are finding them and fixing them), except for overnight, when the air bleeds down a ways.

Just shows how much I know about the governor Grin. The 120 is fine but if I can't adjust the parameters that is okay.

I was also wondering if I could bump the governor to 130 or will that be hard on the air components?

Buswarrior, great words of wisdom. I will check on if we have any leaks the way you described, I don't think we do but we'll see. I agree with what you say about the least amount of pressure on the pedal to do the job, but there is a lot of times that little car that thinks they can squeeze in the gap right between your bumper and the car in front Sad. Our dryer purges rarely as we are driving on the interstate so that is also a good sign.

Sojourner and Dreamscape thanks for the sites, good info.

God bless,

John
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buswarrior
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« Reply #9 on: October 13, 2008, 09:22:35 AM »

Yes, you may up the cut-out to 130 lbs with no ill effects.

Mine is up close to that, and a great number of the newer equipment are leaving the factory up at 130 lbs.

Designed use standard for the components is 150 lbs, with the burst point way up over 300, so you'll be fine at 130.

happy coaching!
buswarrior
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« Reply #10 on: October 13, 2008, 10:04:16 AM »

John, one thing about going from 120#s to 130#s it will help find the weak points in your system on a 20+ year old bus, shoot man it may help by creating others for you to repair (did for me)    good luck
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« Reply #11 on: October 13, 2008, 11:05:16 AM »

Pulling water and other waste out of your tanks also makes a huge difference in available when needed, any water in the tanks displaces air that you may need.>>>Dan
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John316
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« Reply #12 on: October 13, 2008, 12:55:18 PM »

Thanks I will adjust it up to 130.

Dan our tanks are very clean. I have drained them regularly and I haven't gotten anything yet.

I checked and we don't have any leaks in the system.

God bless,

John
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MCI 1995 DL3. DD S60 with a Allison B500.
makemineatwostroke
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« Reply #13 on: October 13, 2008, 01:07:35 PM »

John316; i don't know what make or model of bus you have but before i started changing the air pressure there may be a reason the air pressure is set a 120lbs consult your owners manual. have a great day
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Hartley
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« Reply #14 on: October 13, 2008, 02:02:56 PM »

I would hesitate to fool with the pressure.
You will find a nasty series of problems if the air-bleeder for the filter/drier
is weak. The pop-off ( over Pressure valve ) may get tripped because of a weak spring (old) and won't kick back in until (and if) the presure drops to almost nothing. I had the same problem when I ran my air pressure to 130 psi and it went away when I went back to the 120 psi. The other thing to remember is that old air tanks get weakened by internal rust. Demanding that they hold more pressure than they normally hold is pushing the chance of failure way up.

If you blow a tank you are in a heap of trouble that you really don't
want to deal with on the road.

The older coaches have some quirks especially after years of use and abuse.

Good Luck.....

Now if I could figure out where I parked all will be great...(hehhaaa)...
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John316
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« Reply #15 on: October 13, 2008, 04:30:27 PM »

Makemineatwostroke we have a 95 MCI DL3.

Dr. Dave-Reloaded, good point I will wait till we're home to adjust the pressure. I shore would hate to blow a tank on the road. I think our pressure unloader is good since I just rebuilt the whole dryer.

Thanks for the input and advice, lots more will be needed Wink.

God bless,
John
« Last Edit: October 13, 2008, 06:09:10 PM by John316 » Logged

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« Reply #16 on: October 14, 2008, 10:08:03 AM »

John, it seams you want to make sure that you have enough air to stop in heavy traffic.  Most of the time to make a stop you are only using about 30 to 40 lbs of pressure.  In a hard stop you won't see the gauge go above 100 lbs.  My bus has a duel gauge that gives tank pressure and applied pressure.  I have always been surprised at what a little pressure it takes to stop.  At low speed 10 to 20 lbs.
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Dallas
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« Reply #17 on: October 14, 2008, 10:30:15 AM »

whooooaaaaa, wait a minute...
If you are using 30-40 psi per application, it's wayyy past time to be doing some brake adjustments.

On all my trucks I either had an application gauge or installed one..

If the amount of air EVER went past 15 psi, I knew it was time to adjust. Even in a panic stop, my applications never approached 30 psi.

remember, the longer throw from the slack adjuster to the brake cam, the more air it's gonna take.

Have some one explaing the pinging method of brake adjustment, or it's also known as the "bang on the brake drum" method. Personally, I jack up the the wheel and adjust until the wheel just barely won't turn, then back off 1/8th turn, until it freewheels.
After a few times of this method, you'll know where to set your slack adjusters while on the road.

Good Luck!

Dallas
 

John, it seams you want to make sure that you have enough air to stop in heavy traffic.  Most of the time to make a stop you are only using about 30 to 40 lbs of pressure.  In a hard stop you won't see the gauge go above 100 lbs.  My bus has a duel gauge that gives tank pressure and applied pressure.  I have always been surprised at what a little pressure it takes to stop.  At low speed 10 to 20 lbs.
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« Reply #18 on: October 14, 2008, 11:22:12 AM »

The thing I always adjust when I get on the road with the bus is following distance.   Wink

(not being a wise guy here but it has to be said)

Fred

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« Reply #19 on: October 14, 2008, 12:25:24 PM »

The pressure that I am talking about is the lbs that it takes to apply the brakes.  Not the amount of air used to stop.  I can stop at least 20 times in slow moving traffic before the compresser restarts.
I don't think you can make a max brake pressure stop at 30 lbs.  We must be talking about two different things.  If you have a gauge that shows how much pressure that you have put on the brakes, just push hard and witch it go past 100 lbs.  I am a CDL driver and do know how to adjest my brakes.  Sure would hate to make a panic stop with only 15 lbs. of pressure of course the system would have locked up at 60 lbs.
Jack
« Last Edit: October 14, 2008, 12:35:58 PM by blue_goose » Logged

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Sojourner
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« Reply #20 on: October 14, 2008, 12:31:53 PM »

whooooaaaaa, wait a minute...
If you are using 30-40 psi per application, it's wayyy past time to be doing some brake adjustments.

On all my trucks I either had an application gauge or installed one..

If the amount of air EVER went past 15 psi, I knew it was time to adjust. Even in a panic stop, my applications never approached 30 psi.

remember, the longer throw from the slack adjuster to the brake cam, the more air it's gonna take.

Have some one explaing the pinging method of brake adjustment, or it's also known as the "bang on the brake drum" method. Personally, I jack up the the wheel and adjust until the wheel just barely won't turn, then back off 1/8th turn, until it freewheels.
After a few times of this method, you'll know where to set your slack adjusters while on the road.

Good Luck!

Dallas
 

John, it seams you want to make sure that you have enough air to stop in heavy traffic.  Most of the time to make a stop you are only using about 30 to 40 lbs of pressure.  In a hard stop you won't see the gauge go above 100 lbs.  My bus has a duel gauge that gives tank pressure and applied pressure.  I have always been surprised at what a little pressure it takes to stop.  At low speed 10 to 20 lbs.

Very good safety post Dallas!

That the ways I and many of truck & trailer mechanic friends do.

Thanks for correcting it and you said it well. I was about to respond until yours came in.

FWIW

Sojourn for Christ, Gerald
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« Reply #21 on: October 14, 2008, 01:20:16 PM »

John316....if are worry that your pump may not pumping  fast enough or to spec, just follow the simple tests on page 9 (make sure the compressor's intake filter is clean): http://www.bendixvrc.com/itemDisplay.asp?documentID=2389

blue_goose....you already knew what your talking  about but others need to be more informed with a little detail via Dallas's post. Thank you for your supports.

Fredward...pointing out a rule of thumb about we "bus driver" should always leave plenty of lead spaces to be prepared of the unexpected.  Thank you for your supports.

It not of my business how anyone drive a big long rig on public road, however there has been a number of our pass bus nuts who have lost a limb or two or life as well totaled their coach.

So it very important that your brakes are properly maintain and adjusted at all time. You can have other coach problems but never under estimate the importance of maximumize the care of your air braking system for yours & other's safety. We always want you back safety.

Thank you John316 for your concern and other bus nuts are trying to help each other.

FWIW

Sojourn for Christ, Gerald
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Ps 28 Blessed be the LORD, because he hath heard the voice of my supplications. The LORD is my strength and my shield; my heart trusted in him, and I am helped: therefore my heart greatly rejoiceth; and with my song will I praise him
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« Reply #22 on: October 14, 2008, 04:08:55 PM »

Beats me why you guys want to run these high pressures? Maybe my ole 4104 runs so low because it is so ancient (like me) but it is designed to run between 80-100 psi. As already posted, these high pressures just increase the leaks and the possibility of something failing.

I don't think you get a bit more braking above about 100 but I may be wrong. I'm ready to be enlightened about the advantages of high pressure?

Anyway, the only adjustment on the gov is for max-I think this has already been said.
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« Reply #23 on: October 14, 2008, 05:19:04 PM »

Hello gus.

You raise a very legitimate issue.

The rising pressures over time, from your 100 lbs 4104 to today's 130 lbs multi axles tractor trailers, have more to do with the government regulations and the demanded performance targets of the braking system, than with the fairly straight forward desire to stop.

Higher pressures are said to help with the application timing in the tractor trailers with multiple relay valves and more mileage on the airlines, albeit in a fractional manner. In a straight unit like a bus, there would not be a change of practical magnitude.

Higher pressure also packs more air into the storage tanks, giving the system a greater volume of air in reserve.

The first jump in pressures might have been in responce to the arrival of spring brakes, and the designers wanting a little more breathing room between the bottom of the operating range of the air system and the caging pressure for the springs. (Spring brake needs somewhere around 60 lbs of air to fully cage)

And , as always, how do we really know what pressure we have?

Who has calibrated their air gauge? It is not, and never was, a precision instrument. Off the top of my head, the error factor from the factory today is some horrible percentage that translates into over 10 lbs of air between the dual needles, if someone didn't bend them to align...

happy coaching!
buswarrior
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John316
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« Reply #24 on: October 15, 2008, 04:34:08 PM »

Thanks for all of the input.

In July we rebuilt the whole undercarriage of the bus, which includes the following: brakes, replaced S-cams, all springs, checked all brake shoes, rollers, etc.; we replaced all the bearings, and races; airbags; shocks; and the list goes on. I regularly check the slack adjusters, so I know that they are correct throw. Everything is greased per the MCI maintenance manual. I try very hard to maintain everything that I know of. The problem lies in I don't know everything about it yet, I am still learning. Wink
   
Blue_goose, we don't have duel gauges like you described. When making a brake application it doesn't take much to stop the bus (unless it is a panic stop). I have tested to see if we have any leaks by depressing the brake pedal, with the bus off, and seeing if there is any air loss, which there wasn't. Also driving down the road our compressor runs rarely.

Dallas we do a similar method of adjusting the slack adjuster. Thanks for the advice.

Fred, the biggest thing that we watch is distance. The roofing motto, about black roofing tar, applies here to distance, "Some is good, but more is better."

I really appreciate you all's advice. Braking is a big deal. I have seen to many accidents by not good enough, or not fast enough braking, or not keeping enough distance.

God bless.

John

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« Reply #25 on: October 15, 2008, 06:46:54 PM »

BW,

I can understand how higher pressures will store more air but a pressure reg could easily be installed to limit the overall system pressure past the tanks. As for long trailers, the trailer tanks and relays take care of the distance problem. When I see triple trailers it tells me that is not much of a problem.

I wouldn't trust my 54 year old system with much more than 100 psi, it leaks bad enough as it is!

However, about two years ago when my gov failed the gage went to 150 psi a bunch of times before I found out that the gov was bad. I don't know to this day how all the hoses and connections held up?

Which reminds me, I need to get that extra gov I need to carry in the future. Now that I have rerouted all the lines to connect to the new type gov it can probably be changed in 20 min and a new one is only about $20.
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PD4107-152
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