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
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.
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
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
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!!
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
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
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
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
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
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
trying to make it even more simple - probably failing... ;D
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
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
Rick, I sent you a PM.
Brian
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
Rick,
As Brian has said, DD3 is just another type of spring parking brake, but more troublesome than regular spring brakes. I have them on my 4107 and, believe me, regular spring brakes are far better and I haven't even had to repair them yet!!
Spring parking brakes are spring brakes because they are operated by powerful springs, not air, and are held open by air pressure.
The old ICC is a completely different type of brake, not a parking brake bu an emergency brake only. It will work as a parking brake as long as you have air pressure, but, no pressure, no brake - not good!!
Almost any type of valve can be used with spring brakes as long as it serves the functions of releasing air from the spring brake canister. I've seen the old toggle type that was used long ago to release front brakes only when that was the current thinking.
Thanks Gus,
That was the reason for my confusion, I thought the DD3's were a single canister (non spring) brake original to the 4104 and 4103 bus, I knew I had spring brakes on the 04, just did not realize that DD3's are also spring brakes, so we were talking in the previous posts about 3 different brake systems and I thought we were discussing 2 systems.
My mistake and sorry to all for all the confusion in my previous post's.
Rick
If I wasn't confused before, I sure am now! At this point as much as I hate to do it, I will be taking the Scenic to someone more qualified than me for brake repairs! Normally I aint scared of much, but I just aint willing to play with brakes that I dont know enough about!
Boyce
Boyce,
Probably the most practical sensible post on this entire thread. :)
Take it to someone who will let you watch and if you have to pay them extra to explain everything brake related do so.
Rick
Rick -
To add to the confusion:
The simple way to tell what type of brake chambers you have on the rear drive axle is to determine how many air lines are attached:
One air line = old, original single canister. No parking brake circuit of any type. OEM on your 4104. ICC valve was for emergency braking only, once air in system bleeds off, brakes WILL release.
Two air lines = Current-style spring brakes. Used for both parking brake and emergency brake. Will automatically set if vehicle air pressure drops below about 60 psi. Most common parking/emergency brake cans used today, along with the yellow push/pull valve. Simply pushing valve down when coach low air warning buzzer shuts off will frequently release the brakes.
Three air lines = DD3 brake chambers. Used for both parking brake and emergency brake. Like spring brakes, will automatically set if vehicle air pressure drops below about 60 psi. Due to design, requires a full service brake application for 3 - 5 seconds with coach air built up to 100+ psi before they will release. No longer in production, rebuild kits available.
IMHO, if your coach, in fact, does have spring brakes, I'd suggest you figure out how to remove the ICC valve and properly plumb in one of the common yellow valves. Think of this modification as a safety issue - if somebody unfamiliar had to move your coach (such as a tow rig) - they'd easily recognize the yellow parking brake button, whereas the old ICC valve would probably make them go "huh?"
FWIW & HTH. . .
;)
A warning to busnuts:
It would be best to be very cautious in choosing someone to work on the brakes of your coach if re-design or re-engineering of the system is required.
Sad to say, that mechanic may be more stunned about the situation than you are.
But he will take your money and pretend really convincingly.
There is nothing in a traditional mechanic's training that equips one to build a brake system.
Maintain a stock one? yes.
Design or re-design? a very loud NO!
be careful.
happy coaching!
buswarrior
Someone please correct me if I am wrong, but I do believe that DD3 ARE NOT spring brakes. The two types of systems operate on completely different principles.
Correct. DD3 chambers are not spring brake chambers.
I think the various posts are playing fast and loose with a variety of terms.
Both DD3 and spring brake chambers have combined service and parking features.
The parking feature is also employed in some fashion as an emergency brake in both systems.
Spring brake chambers for parking use have widely taken over as the only solution for activating drum brakes on today's heavy vehicles. DD3 stopped being manufactured by Bendix at the end of 2008.
DD3 came into use before spring brakes, use air from an isolated tank to activate the parking portion, as well as there being locking rollers to prevent release when the air pressure leaks away, and air from another tank for the service portion. This redundancy was unheard of at the time of their invention, everyone was parking with handbrakes and air applied parking circuits in single circuit air systems. Wheel chocks ruled the day in the heavy vehicles.
happy coaching!
buswarrior
Thanks to everyone who posted, I for one feel better educated about not only the brake system on the 4104 but the other types of brakes as well. If this information keeps anyone out of trouble it was worth it.....I will be checking into replacing the ICC value with the one I should have.
Rick
Print out the Air brake Handbook and study it thoroughly. Just about everything you need to know is there. Every bus nut should have this available.
http://www.wsafc.org/WSFMA/Shared%20Documents1/Bendix%20Air%20Brake%20Handbook.pdf (http://www.wsafc.org/WSFMA/Shared%20Documents1/Bendix%20Air%20Brake%20Handbook.pdf)
So looking at my MC5, single line fronts, triple line rears, I have DD3 on rears, and old single cannisters on the fronts? I have noticed I have to apply the brakes pretty good to unlock them.
RJ says to update the old spring brakes, BW says to maintain stock. I'm guessing I could install a yellow air valve in place of the stock black knob so it would appear current to anyone, leave the rest of the system alone and just bring it all up to kosher??
Paul, on my mc7 the fronts and the tags are single line brake chambers. Only the drive axle brakes are the three air line system. That's the parking brake. John M.
Quote from: artvonne on March 03, 2012, 09:56:09 AM
RJ says to update the old spring brakes, BW says to maintain stock. I'm guessing I could install a yellow air valve in place of the stock black knob so it would appear current to anyone, leave the rest of the system alone and just bring it all up to kosher??
Paul -You've misunderstood my comment to Rick. I was suggesting he replace the old ICC valve with the current yellow push/pull, since his coach now has spring brakes.
For your coach, it ain't broke - don't fix it!
FWIW & HTH. . .
;)
Quote from: RJ on March 03, 2012, 11:21:46 AM
For your coach, it ain't broke - don't fix it!
Is there any physical or mechanical difference between the old style black knob brake valve I have, and the newer style yellow knob brake valve? I thought both were simple dump valves to blow the air.
Paul,
To repeat other posts, if it works don't mess with it. I spent untold frustrating hours trying to eliminate the ICC valve and gave up. It works and works well.
4103s and 4104s came with only the mechanical drum parking brake. The result is that it is very tight fit to install spring brake chambers, but it is well worth the trouble. I don't think I could ever trust those drum parking brakes.
I may have given you the impression that DD3s are spring brakes but they aren't. I sometimes get confused on that myself because they work pretty much the same from the driver's seat. Mine will hold without being set by foot first but I usually do it anyway. However, as already posted, they usually must be released by foot after pushing in the knob. However, again, mine release automatically about 90% of the time if I haven't pushed the pedal in real hard to set.
That really clears it up!!!
Springs are better.
Are the ICC brakes just a service brake pod as we call it today ?,brakes are fairly easy to upgrade not a rocket science I have seen on old GM's the lever replaced the with a air parking brake
I installed a hydraulic parking brake on the wife's S&S tied to the braking system push the pedal down flip a switch locks the drum on transmission and both axles brakes
Clifford, IYHO
So would it be a good idea to upgrade from DD3 to spring brakes on my MCI 5C and if so what am I look at parts and Labor aprox or just parts.
Dave5Cs
Quote from: gus on March 03, 2012, 12:59:30 PM
4103s and 4104s came with only the mechanical drum parking brake. The result is that it is very tight fit to install spring brake chambers, but it is well worth the trouble. I don't think I could ever trust those drum parking brakes.
Not recommended, don't try this at home...25 years ago and not as wise, I drove a GMC PD3751 home without air brakes, just the driveshaft hand brake. I could lock the rear axle if I hauled back on it hard enough and would leave rubber and smoke. It was a very powerful brake, one I wish this newer Bus had.
The colour of the knob matters not. The function of the valve it is screwed onto is of more concern.
This thread scares me in some respects.
If you own a bus conversion, you need to know how your brakes are supposed to work, and then check them to be sure they do. Or, be prepared to locate a reliable agent and purchase that service. Regularly.
This has to do with your responsibility to yourself, your family and the rest of us, the traveling public.
Please, proudly purchase current airbrake training materials, spend several evenings reading everything you can find from REPUTABLE SOURCES, not this or other internet BBS. What do you know? What do I know? Ignorance didn't stop either of us from typing words on here.
Bendix has an extensive library and lots of technical articles.
I am quite fond of "Practical Airbrakes" found here from the CVSA: http://cvsa.stores.yahoo.net/pracairinhan.html (http://cvsa.stores.yahoo.net/pracairinhan.html)
Strongly consider taking a proper air brake course at an educational establishment. A course for a technician would be even better than one for a driver, but both would be good.
For the MC5 question, it is a big job to swap spring brakes into an MCI, MCI took full advantage of the smaller size of the DD3 brake chamber in their suspension design. There is insufficient room to mount a spring brake chamber in the same place. Modifications involving heavy welding of new mounts is required, as well as hardware.
There is nothing wrong with a DD3 system, MCI was using it up into this millennium.
As for reliability, if a busnut changes out the inversion valve as part of their new bus preventive maintenance, give the chambers one pull of grease each, the chamber diaphragms are no worse at aging than those in a spring chamber, and may be changed out, unlike a spring chamber, which must be thrown away, and has a dangerous coiled spring contained inside.
Don't leave them lying around to maim the kids or the dog when they rust through.
happy coaching!
buswarrior
Amen, BW, Amen!
;)
BW thank You for the info.
"if a busnut changes out the inversion valve as part of their new bus preventive maintenance"
Meaning a new or to rebuild one. Not to something else or newer correct?
Dave
Sorry, remove and replace the inversion valve with a fresh one.
Maybe $100 or so? For busnuts, I recommend just purchasing a ready to go valve. We lack the knowledge to make the crucial decision on whether a valve core is in suitable condition for rebuild or not. And the spread on the cost of the kit and a fresh valve isn't worth the time to most of us. No large fleet that I know rebuilds anything anymore, not worth the time, and the potential for error and having to redo it again.
The maintenance manual recommends changing the inversion valve on some periodic basis, which you can be absolutely sure that it hasn't been. Achilles heel, very few fleets change them, and the last commercial operator wouldn't even know that there was one...
It's function is critical to coach operation, as a DD3 system must be pressurized one way or the other to both park and to drive.
You control the inversion valve with the push/pull valve by the driver. The inversion valve switches where the parking air is directed, to the chamber parking portion to park, and to the chamber locking rollers to go for a drive.
When it has decayed sufficiently, and starts leaking, or refusing to fully switch between the two modes, you've got trouble that could have been avoided.
Mounted on the differential, a sawzall run vertically down the side of the valve body tight to the threads will quickly dispatch the large corroded nut that holds it on. Be sure to stop before you cut through the mount.
Also a great time to gather up all the hoses and have some fresh ones made up. If they are seized, easiest to label them, and just cut them to make removing the remains easier. And while you are there, and this far along, swap out the the rear service relay valve and the parking circuit regulator for new ones, and there's little left to worry about back there for a decade or more.
Use the anti-seize of your choice during assembly, everything with threads and mating surfaces, careful to keep it out of the inside of the airlines, but under the mating surfaces of the fittings, cuz you'll be very mad at yourself the next time...
happy coaching!
buswarrior
You guys not all spring brakes are a throw type or tamper resistance as they are called now that has just come into play in the last few years spring brakes are easy to service not like the DD-3 and the SD-3
You cage the spring with the bolt that comes with those and the spring is not a problem replacing a $5 diaphragm compared to $100 diaphragm for the DD-3 or the SD-3
If a spring brake canister has a V type band with a bolt like a service brake pod it is serviceable problem came when some nut twister releases the band before caging one and hurt himself.
To many moving parts in a DD-3 for a brake system IMO that is why Bendix sent those to the big house in the sky and refuses to support or supply parts for the DD-3 or SD-3 any longer long live the springs lol
good luck
You would re-use, or attempt to disassemble, a spring brake chamber typically found on one of the coaches that we busnuts end up with?
I am lacking in that courage now.
happy coaching!
buswarrior
Good point lol but I have seen some bad looking DD-3's come off these buses no way could you rebuild one
Yes, no matter which way a busnut goes, worn out, rusted up parts, assembled in unorthodox manners is the mainstay of the early years of troubleshooting.
happy coaching!
buswarrior
Rick,
You owe no apologies. The 4104 brake system when modified with spring brakes and, like mine, keeps the ICC valve plus the yellow spring brake valve, can get very confusing. I never did figure out the plumbing on mine. Tried to remove the ICC valve and nothing worked! Gave up and left it!
It appears yours uses the ICC valve to set the spring brakes, a simpler system than mine and not as dangerous since pushing IN my ICC valve locks the brakes - really weird!!
On top of this the DD3 is another parking brake system altogether, but works fine, not as simple or trouble free as spring brakes though.
The original mechanical parking brake has nothing to do with any part of the air system. That whole system must weigh 300 lbs.
Wow, what a thread! I am away for a day and so much happens. Hopefully it's now clear, but for the record DD3's are completely and totally different from spring brakes, the only similarity is they both are parking brakes, and they both work with a knob that the driver can push and pull. One correction I did not see any one else catch - in many, if not all, installations they do not apply automatically when the service air pressure drops to 60 psi, or even zero. That is because the parking/emergency function is based on air provided by the independent, protected by check valves, parking/emergency brake tank. Only when it gets down to the pressure dictated by the spring inside the push/pull valve - (20 - 45 psi per BW, I never bothered to test mine) - will the valve pop and the brake apply with the remaining pressure. The way to test this is a two step process - first air up the bus, drain the wet tank then the dry tank to zero. See if the valve has popped - if the check valves that protect the parking brake tank are working right the valve will not have popped because the parking tank will have full pressure in it. Next drain the parking brake tank and the valve should pop when the pressure gets down. If you want to know at what pressure the valve will pop at, just drain the entire system from the parking brake tank. The pressure in the whole system will drop and the pressure gauge will follow the pressure down, so you can go look when the valve pops and see what the pressure is at.
One other note - brand new DD3's are available from REI. I bought a pair and was quite happy with the quality, and the service was great. I would go a long way to avoid replacing the brakes on an MCI like mine with spring brakes. Clifford says he's going to, but I won't (and didn't) if there is a reasonable alternative.
Brian
Quote from: Len Silva on March 03, 2012, 09:48:36 AM
Print out the Air brake Handbook and study it thoroughly. Just about everything you need to know is there. Every bus nut should have this available.
http://www.wsafc.org/WSFMA/Shared%20Documents1/Bendix%20Air%20Brake%20Handbook.pdf (http://www.wsafc.org/WSFMA/Shared%20Documents1/Bendix%20Air%20Brake%20Handbook.pdf)
That version is marked " (C) 2004. I have two version on my harddrive marked 2008 and 2009. I don't know where I got them (I'm guessing the Bendix site) but it would seem best to go with the latest issue.
There is one really bad fault with mechanical drum parking brakes and with no air, if the U joint fails you have nothing!!
Even 25 years ago I wouldn't have had the guts to drive with only this brake!
I have a few antique heavy trucks with this setup and this part always worries me.
First cars I owned had single master cylinders, one leak and no brakes. First cars my Dad recalled had only rear brakes, only they were mechanical. Next came four wheel mechanical, then hydraulics. You still see Choppers with no front brake, though I think thats kinda nuts. So its really your point of reference more than anything.
While I admit I drove the Bus home with only the parking brake, I doubt I ever got the Bus over 30 mph, and would slow down so far in advance of a stop sign or turn I didn't really need to brake. And it was barely 3 miles and all back roads. And driveshafts don't normally explode without some warning.
I've had plenty of U joints go with no warning and others with, all depends.
At 30 mph a 20,000 lb+ bus will roll for miles.