Spring Brakes with ICC Brake Valve?

[Rick59-4104]

 My 4104 has double chamber brake canisters which is telling me spring brakes but my brake release valve on the floor by the drivers seat is a 2 position ICC Brake Valve with emerg in the forward position and normal in the back or rear position is telling me DD3's. I can pump my brakes to bring down the pressure and the brakes do not set themselves.

Is it common to use the old ICC Brake Valve with spring brakes? I would expect to have a push/pull with the spring brakes. The ICC brake valve is leaking air in the normal position from the top of the valve, wondering if I can/should replace the ICC with a push pull valve or is there a reason the previous owner kept the ICC Valve??

Any of this make sense?

Thanks in advance,

Rick

[papatony]

Rick I have a 4106 that has brake valve, the purpose of that switch has to do with dry roads ( front brake and back work together) wet weather the rear brake engages before the fronts. The brakes do not lock down when the air goes down.  you should have a hand pull parking leaver on the left of driver.

[buswarrior]

Yes, a toggle/lever style air valve of the appropriate model may be used for a spring brake control.

However, since whatever plumbing you have has been modified/added by some previous owner, all bets are off to anything that might be called standardized.

When testing for the reaction to low air, it is not the action of the control by the driver that matters, it is whether the spring brakes are actually applying at the wheels.

I expect that you will find the springs moving the brake linkages somewhere ahead of 60 lbs as the pressure is dropping.

If this was to happen while underway, the coach may have already safely stopped itself, before the control by the driver does anything. Two separate events, two separate return springs acting against the lowering air pressure.

happy coaching!
buswarrior

[Rick59-4104]

 Did some checking tonight and yes Martha you can have spring brakes with the old DD3 ICC valve to set them. I would have thought a conversion would have included a square yellow push-pull that would apply the brakes when air pressure drops below 60 PSI.

I would say that confusion and lack of knowledge about the different air brake systems on these old buses is the number one thing that could get someone new to buses and air brakes in serious trouble real fast.

Thanks,
Rick

[gus]

My 4104 has this valve and spring brakes with two chambers also.

I don't think that is a DD3 valve, it is an ICC valve that was used for emergency application of brakes only - not for parking. Once air is lost the brakes release? The 4104 Driver's Manual says not to use this for parking.

My 4104 has both this valve and spring brakes operated by a separate current type yellow spring brake valve. With the ICC valve open everything works normally. With it closed air pressure won't build up and the brakes are locked?

It is very confusing to me. I tried to trace out the lines once and gave up after going into the black hole under the driver. I just locked it open and went on my way. You don't ever want it unlocked because if anyone accidentally pushes it down the brakes lock. Very weird!!

[Rick59-4104]

 Thanks for the replys, Gus you are right, from what I have read the ICC valve was for emergency use only, the person who added spring brakes to my bus ran the air lines to it so it is what I use to set my spring brakes, this caused me some confusion. It is leaking air so I am going to replace it with what not sure.

My 4104 and my 4103 both had the hand lever operated drum brake on the driveshaft outboard of the transmission for the original parking brake.  It was removed from the '04 I guess when spring brakes were added. Lots of air brake information in past posts and on the web but for a lot of us with changes made by previous owners it can get confusing as to just what was done. Things could get bad for someone used to spring brakes in a bus with DD3's who thinks you can use the DD3 as a parking brake. My advice to anyone not sure would be to block the wheels when parked.

Another problem is when you adjust your rear brakes but back the adjustment off instead of tightening the brakes,( and it is easy to do) then when you set the brakes and go to exit the bus it is leaving the parking lot heading for a new zip code as you step out. Don't ask how I know this can happen.

Rick

[wildbob24]

Rick said:

"Things could get bad for someone used to spring brakes in a bus with DD3's who thinks you can use the DD3 as a parking brake"


Just to clarify: DD3s are parking brakes that function much like spring brakes. They use air pressure and a locking mechanism to actuate, instead of a spring.

The original ICC control on the old GMs operated the original single function rear brake chamber as an emergency brake only, not a parking brake. I believe this is what Rick meant to refer to.

Bob

[Rick59-4104]

 Thanks Bob, not sure I was making myself clear. Correct me if I am wrong, (and I may be) when you lose air pressure with spring brakes the brakes will set (when pressure drops below 60PSI with the square yellow valve like trucks have) but with DD3's if you lose air pressure or your air pressure bleeds off the brakes release???



Rick

[wildbob24]

Rick,

If your spring brake system is working properly, the low air warning should come on at 60psi and the brakes will automatically apply at 25-45psi, usually around 30psi.

DD3s have an internal locking mechanism so that as the air pressure bleeds off, the push rod cannot retract. So, if your DD3s are working properly, they will not release when the air pressure drops.

Bob

[buswarrior]

No, that is not what spring brakes do.

There are two issues: the spring in the chamber, being held off by the air pressure in the tank, and the control valve by the driver, that has a spring in it that is held off by air pressure in the tank.

The spring in the control valve by the driver will pop wherever it does, (or it won't) popularly advertised as 20-45 lbs... hardly a creature of precision.

The springs in the chambers, the ones that matter, as they are the ones that will stop you when the air has gone away, they will be moving the brake linkage as the pressure drops to the 60 lb range, if they have anywhere near their proper strength left in them. For many, many years, the spring portion of the chamber is only strong enough that it may be overcome by an application of 60 lbs of air.

Unfortunately, driver trainers teach some foolishness in pre-trip while the vehicle is sitting still... how would you know the brakes have already applied due to the loss of opposing air pressure against the springs, long before the control at the driver pops?  And, there is no statute I am aware of that requires the control to do anything under low air pressure conditions.

Again, the things that unknowing driver trainers have blindly repeated to compensate for their lack of knowledge as to how the system functions.

Which is to say, we busnuts have even more research to do, cuz we can't trust popularly held notions in the transportation industry either!!!

happy coaching!
buswarrior

[papatony]

Rick  lets make this simple IF YOU HAVE A HAND PULLER EMG. BRAKE  BETWEND DRIVER AND WALL VALVUE WILL NOT LOCK THE BRAKES. if you do not have this brake then you have a bad valve, the push-pull buttons will work. IT WORKES ON MINE        TONY

[bevans6]

trying to make it even more simple - probably failing...  

Spring brakes apply when the air to the spring chamber goes away - it matters not what makes the air go away.  The air can bleed away slowly, or the air can be dumped from a valve - if the air drops below 60 psi, the brakes apply.  If your valve can dump the air to the spring brake chamber then it can apply the brakes.  The reason that the normal push-pull valve also pops by itself when pressure goes away is NOT to apply the brakes - they are already on since they applied with the pressure dropping past 60 psi while the push-pull valve only pops between 20 and 45 psi - it pops to make sure the brakes stay applied when the air pressure is restored.

DD3's in typical use are the polar opposite.  They need air pressure to apply the parking brake function (which is also the emergency brake function), they lock on by themselves mechanically and they need air pressure at the locking port AND the service port (not the parking brake port like the springs brakes) to release.  With DD3's the push-pull valve also pops automatically at 20 - 45 psi but unlike the spring brakes this will indeed apply the parking brake with the residual pressure of 20 - 45 psi left in the parking brake tank.  Almost completely opposite to what the spring brake system does.

To Rick, the OP - the position of your valve can have nothing to do with the application of your spring brakes - if indeed you have spring brakes!  The only thing that applies spring brakes is the absence of air pressure at the spring chamber port.  The valve is only one way to apply or remove pressure there, not the only way.  The value of the more modern push-pull valve is in the automatic pop-up that makes sure the spring brakes stay on if air pressure is restored.  The real thing you need to do is sort out exactly what modifications you have, and make sure it works to modern standards.

Brian

[Rick59-4104]

 Brain,
Thanks for the information, it is apparent to me after reading past post's and the answers on this thread that with the different brake applications and the modifications made to the brake systems on these old bus's all things brake related can get confusing.

In regard to your post on the new BNO forum about this thread and my lack of knowledge about the brake system on my 4104 please read my first post on this thread. I can see how my first post can be confusing but I do know and have known since I bought the 04' that I have spring brakes on the bus, and I do have a basic understanding of how spring brakes work.... my original question was about using the original ICC Valve with the spring brakes and how common this is. Not trying to be thin skinned here but I don't  really like being "put down" on the other forum for asking what I believe to be a valid question.  Thread closed as far as I am concerned.

Maybe I am reading more into your post on the other forum than I should, I'll drink another cup of coffee and see how I feel  


Rick

[bevans6]

Rick, I sent you a PM.

Brian

[Rick59-4104]

 OK world, had that second and third cup of coffee... Brian and I are OK ...I can see where my post's on this subject can be confusing.


Rick