| Author |
Message |
Timnvt (Timnvt)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 28, 2006 - 8:40 pm: | |
Fired up the coach this evening to move it into the garage for service before our spring trip. The coach has been parked out in the cold and damp all winter.
Bad news. The coach WON’T MOVE.
The air is up to 120psi, the push pull brake valve appears to be working properly and the brake stop light switch does go off after depressing the service brake.
I think the brake shoes are stuck on the brake drums. The coach won’t budge forward or reverse though she strains hard to do so.
The coach is a '66 mc5a with an automatic tranny.
Any ideas how to free this rig?
Thanks, Tim. |
Ross Carlisle (Rrc62)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 28, 2006 - 8:50 pm: | |
My MC9 did that a couple years ago. I got it freed up by pumping the brakes with max pressure on the system. With full pressure, press pedal to the floor, hold then release. It took a while to get it to unlock. That spring I pulled the wheels and greased everything that should be greased and it hasn't been a problem since. |
Possumlodge
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 28, 2006 - 9:25 pm: | |
My MCI-5c has same problem. It has a tag on the switch panel that says to run up pressure until governor stops compressor.Then pump brakes until it goes bellow 60 pounds.LET it build back up and try releas if it dont work repeat.When mine sits for a while I have to go through this cycle 2 or 3 times. I hope this helps |
Bill Gerrie (Bill_gerrie)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 28, 2006 - 11:05 pm: | |
Tim
When mine does that all you can do is to release the brake and put in gear and floor it monentarily then put in reverse and floor it again but be careful if it releases you will take off. You may have to do this a few times to get the brakes to release. The shoes will bond to the drums with the parking brakes applied. I made up a rig to put between the slack adjuster and the radius rod to hold the shoes away from the drum all winter when the parking brake is applied so I don't have that problem anymore. Bill |
Dave Wilson
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 28, 2006 - 11:07 pm: | |
What ever you do dont try to brake it loose by putting forward and reverse. I not sure what part of the country your in but if there is any moisture in your air system your maxis will not release shut down open airline coming out of air compresor and add brake saver if available or methol hydrate dont make a habbitt of using methol hydrate it will rott your orings in your air system ,if that doesnt work completly drain air ststem each air tank one at a time and repeate above . Sounds like you have a air compressor thats passing oil. |
Dave Wilson
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 28, 2006 - 11:15 pm: | |
What ever you do dont try to brake it loose by putting forward and reverse. I not sure what part of the country your in but if there is any moisture in your air system your maxis will not release shut down open airline coming out of air compresor and add brake saver if available or methol hydrate dont make a habbitt of using methol hydrate it will rott your orings in your air system ,if that doesnt work completly drain air ststem each air tank one at a time and repeate above . Sounds like you have a air compressor thats passing oil. |
John MC9
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 28, 2006 - 11:40 pm: | |
Tim -
Ross and Dave have it right. Trying to pull forward or back
with the brakes set can do some very costly damage. Lightly
pulling against them is one thing, but to go full bore? Never.
If the parking brake was set with the air at 100 lbs, it'll need
100+ lbs to release 'em.
Worst case scenario? You'll have to (block the wheels) jack,
block, and re-adjust the brakes that are bound. After they're
released, and the bus moved, re-jack and block, and re-adjust.
Try what Ross suggested first; that's what worked for me,
and probably countless others. |
Buswarrior (Buswarrior)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 28, 2006 - 11:42 pm: | |
Hello Tim.
For fun, take both Bill's and Ross's strategies and mix them together.
You have to convince the rust bonding between drum and shoes to break. Release the parking brake and using two feet, one on each pedal, with full air pressure, once you wind it up trying to reverse, nail the brake hard, then wind it up trying to go forward and nail the brake hard. You have to get that rust to seperate using whatever force you can apply and release, brakes or engine, together and in different directions will help get it to snap free.
If it is still stuck, see if you can manage to see the rear brake linkage to confirm there is some sort of movement. You'll need an assistant to manipulate the parking controls and a good flashlight. Try using a mirror if you can't see it directly. Movement will be slight, but you are looking for any confirmation that your problem is indeed drum/lining related and not air valve related.
For future storage, to reduce the chance of the linings rusting tight to the drums, with the drums having been cleaned up through use, once a month or so, air up the bus and release the parking brake. It won't get a chance to bond if it is moved away from the drum periodically.
You may use a shop compressor instead of the engine, if you don't want to run the motor.
Also, as Ross noted, less than smooth linkages may add that straw to the camel's back; do some lubrication on your pins and shafts.
happy coaching!
buswarrior |
bruce knee (Bruceknee)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 28, 2006 - 11:56 pm: | |
There is no easy way to do this on a bus, the best way to get rusted brake shoes unstuck is with a 5 lb hand sledge. You need to strike the edge of the drum from under the bus. The brakes need to be released when you hit the drum. Don't get run over. |
Buswarrior (Buswarrior)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 29, 2006 - 12:23 am: | |
Hello.
What forces are put on the brake parts when you apply the brakes hard on the street or highway?
Which expensive parts will be damaged?
You won't break anything that isn't already broken by using the bus's own power in a measured attempt to get stuck linings free from the drums.
And if its own power doesn't do it, Bruce's 5 pound solution is the next strategy to follow.
Let's keep this all in perspective.
happy coaching!
buswarrior |
John MC9
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 29, 2006 - 12:39 am: | |
Truck garage in Bernardston, Ma., did over $2k of work,
due to a driver trying to move an Eagle while the brakes
were not released.
The torque applied to the drivetrain, when attempting to
drive off while the brakes are set, is tremendous.
It's your piece of heavy equipment, do as you please. |
Phil Dumpster2
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 29, 2006 - 2:10 am: | |
$2K for a set of U joints is a lot of money, since that's the only thing you're going to break by forcing the coach with the engine.
Specifically, it's the U bolts that hold the end caps of the joint, but you end up replacing the joint anyway since all of the pieces go flying.
The 5 lb lump hammer is the best and most gentle solution, and with a 12 inch drift punch you can even direct the force to the brake shoe itself, which is my preferred method.
Of course, the coach has to be blocked up securely before you get under it.
Having said that, there is no harm in gently using engine power back and forth to break the shoes free.
The best thing is to not leave the coach sitting in one place long enough for this to happen to begin with. |
t gojenola
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 29, 2006 - 5:46 am: | |
My theory:
Shoes frozen to the drum? Not very likely the problem. If this coach has DD3 chambers and sat over winter in the locked (park) position, it's more likely the locking mechanism on one or both sides that's stuck. Powering up and rocking back and forth won't break it loose.
You need to block it up so you can safely get under there to determine what the real problem is.
tg |
Marc Bourget
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 29, 2006 - 6:08 am: | |
I offer there's some practicality, at least in a fairly level parking spot, to chock the wheels and release the brakes for extended parking intervals.
I've wonder that modifying a "Club" to lock 'em in place wouldn't work well and otherwise not "grow legs" |
bruce knee (Bruceknee)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 29, 2006 - 6:22 am: | |
Hey TG, $50, say it is the shoes rusted to the drums, and all it will take to break them loose is a couple wacks with a hammer |
Bill K
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 29, 2006 - 6:48 am: | |
Take it easy with using power to free the brakes, I have a friend that tried that with a dump truck, several thousands later he had a new rearend back in. |
airless in Mississippi (Airless_in_mississippi)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 29, 2006 - 7:05 am: | |
Reach down from drivers seat pull hard UP on the brake pedal see if that will free the brakes. |
JimH
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 29, 2006 - 7:27 am: | |
Did the hold the brake and hit the gas thing once. Twisted the drive shaft like a screw -- of course this was with a 60 series. Your mileage may differ.
JimH |
Dave Wilson
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 29, 2006 - 7:33 am: | |
Like i said previously i had a`young fellow`driving one of my coaches a few`years back tryed to brake the coach loose a copletly trashed the bango. My 9s are parked outside all winter long go threw what your saying all the time it points to drivers not draining the air system full of moisture , |
Stan
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 29, 2006 - 8:20 am: | |
Isn't the complete driveline designed to take the maximum torque available?
On many buses you can't start up a steep slope. You don't have enough power. Does this also tear up the driveline and differential if you try it?
I live in low humidity area so I never had the problem of brake shoes rusting to the drums. |
Greg Roberts (Gregeagle20)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 29, 2006 - 8:23 am: | |
How did you eliminate your service valves as the problem? Does your bus have an emergency air system that will allow you to apply this air for a test? I would put my money on the air valves being the issue rather than the brakes bonded to the drums. Are both stuck not moving when you attempt a brake release? If so, look at the air valves. |
John MC9
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 29, 2006 - 8:42 am: | |
Phil -
"Having said that, there is no harm in gently using engine
power back and forth to break the shoes free. "
Isn't that what I said?
"Trying to pull forward or back with the brakes set can do
some very costly damage. Lightly pulling against them is one
thing, but to go full bore? Never. "
Whatever...... |
John MC9
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 29, 2006 - 8:57 am: | |
Stan -
I always swear I won't argue with you. but then I go doing this...
Re:
"On many buses you can't start up a steep slope. You don't
have enough power. "
I've driven Eagles, MCIs, GMs, Flexi's, etc etc... The automatics
geared for city use had a tough time on ski charters. Those with
standard transmissions would walk away at idle, regardless of
the hill. There's more than enough engine power, but some
automatics did not transfer all that power to the drive train as
well as a standard. Regardless, I never drove a bus that couldn't
start up a hill under it's own power.
If a driver's going to race the engine, snap up the clutch against
locked brakes, there's going to be more than U joints damaged.
It's fun to argue hypothetical problems, but some of us that
have witnessed the aftermath of the deed, know just a bit
better than to do it. |
mci 5a frank
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 29, 2006 - 9:02 am: | |
Hi Tim I have had similar issues from time to time. My solution so far has been to press the service brake to the floor repeatedly until the dd3's release (the more air the better) You can also try engageing and releasing the parking brake valve. This has worked for me. It is pointless to try to hammer on the wheels or force the coach with the engine. Good luck |
Stan
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 29, 2006 - 10:32 am: | |
John MC9: I didn't ask you. I was hoping to get an answer from someone who understands how torque converters work and how axle ratio affects torque to the wheels. |
John MC9
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 29, 2006 - 11:02 am: | |
Uh-huh. OK. |
Timnvt (Timnvt)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 29, 2006 - 11:28 am: | |
Well, FINALLY the brakes have yielded to the persuasion of the drive train.
Thanks to you all for your ideas and encouragements. I have to say that I did try tapping the brake shoes with a steel rod and hammer but to no affect. In the end it was continuing to applying and releasing the service brake and the parking brake in every conceivable combination and attempting to work the coach forward and back that she began to move. I’m sure glad it was an automatic and not a standard tranny!
The drivers side freed up first which concerned me that this could create trouble by torquing one axel against the other. I don’t think I did any damage though.
So, now I will be able to bring it inside and up on blocks to inspect and service the rig. Hey, Vermont is pretty but I sure envy you fellas south of the snow belt.
Thanks again everyone, Tim. |
Gary Stadler (Boogiethecat)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 29, 2006 - 12:24 pm: | |
Guys, here's a thought about why your driveline might get eaten if you step on the fuel pedal while the wheels are locked up...
If a bus is working normally, at a stop, you have an automatic tranny, and you want to go, you put your foot on the fuel pedal, engine torque builds up, and is multiplied by the tranny's 1st gear ratio.
As soon as the torque gets high enough to make the bus move, it moves, the torque quits building and starts the bus in motion. The "fuse" here that limits the torque to levels within driveline ratings is the fact that the bus has started moving, thus maintaining or reducing torque but never allowing it to get any higher.
Even with a fully loaded bus aimed up a hill, the maximum amount of torque that the driveline will see is "just enough" to make the bus move, and hopefully if the designers have done their job, well within driveline limits.
Now consider a locked-brake situation. The engine/tranny can very likely generate a whole lot more torque than it takes to simply move a loaded bus aimed uphill, and with the brakes locked and in first gear, it will.
That is what can rip up driveline components...
with the brakes locked, there is no longer a "fuse" (ie bus begins to move) to limit the torque. So the next link in the chain dies... a driveshaft twists, a U joint snaps, a rear end gear tooth breaks off, etc....
As an aside but related, back when we used to practice for the Plymouth Troubleshooting contest in the 60s we would take a car from cold to running temperature in less than a minute by putting it in first gear, stepping on the brake pedal, and flooring it. Due to the locked drivetrain, the engine would dump it's entire horsepower into the torque converter and heat up very quickly... and more frequently than we'd expect, we'd break an engine mount in the process. That was with new cars...well designed for torque expected during driving but not nearly stout enough to hold back a locked driveshaft in first gear with the engine roaring...
|
Jarlaxle
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 29, 2006 - 6:08 pm: | |
"$2K for a set of U joints is a lot of money, since that's the only thing you're going to break by forcing the coach with the engine."
Not at all difficult to smoke the transmission doing this. Even with big coolers & deep pans, I've seen fluid temps soar over 100 degrees in only 30-45 seconds of heavy throttle/wheels not turning. |
t gojenola
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 29, 2006 - 7:04 pm: | |
A couple of things about DD3 chambers that are worth mentioning:
The parking diaphram in a modern DD3 chamber is designed to be supplied with an 85PSI regulated air pressure, and most vehicles are set up this way. When you make a parking application, 85 pounds is applied to the chamber, the rod is pushed accordingly, and the locking rollers applied in that position. This will allow the rod to be moved additionally by a service brake application so that the locking mechanicm can be released.
However, some people make the mistake of applying the parking brake while the service brake is being applied full on. When this happens, it becomes very difficult to release the parking brake since no appliction will move the rod far enough beyond the locked position. The remedy for this in my old trucking days saw a mechanic with a long ratchet backing off the slack adjusters while the driver was getting chewed out.
Occasionally the parking brakes are applied while the drums are hot and thus expanded. When they cool they retract, and the parking brake will not release due to the back pressure thus applied against the rollers.
One other rare problem I have seen was caused by cheap brake linings that expanded when they got wet and stayed wet long enough, causing the same problem.
This may not relate to the problems prompting this thread, although I believe it does. But it may help someone avoid starting another one like it.
tg |
Dave Wilson
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 29, 2006 - 11:48 pm: | |
While seating in your Mc8 or 9 look to your left you will see a warning label telling you not to attempt to brake coach loose.I almost positive your air system is contaimenated with water and or oil. My coaches are operated in some the most harshis climates around i have sniffer bottles wich inject brake saver into the system everytime the compressor loads and air bleed from all tanks daily and i still have problems one day it could be 45below the next 10 below now there is moisture. That is what causes the problem. |
truthhunter@shaw.ca
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 30, 2006 - 12:32 am: | |
Shouldn't it also be mention that alcohol can't be used in that old sniffer bottle if the old coach had a air dryer system added at some point in it's life (like on my old MC 8). And of course with a air dryer that has been maintained there is no need to worry about moisture getting into the system, or so I have been told??? |
Dave Wilson
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 30, 2006 - 1:54 am: | |
I keep my old mc9s maintained cartriges changed three times a year but still need sniffer on the system to avoid problems it doesnt look to good when you try to depart with your clients and your frozen to the ground . |
truthhunter@shaw.ca
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 30, 2006 - 9:47 am: | |
That leaves me in a little confusion about the drier and alcohol sniffer. My factory sniffer is in the engine compartment just down line from the compressor and the dryer/ with moisture ejector is located forward of the front axle. I was told that if the sniffer was used it would saturate the dryer cartrige and cause it to dissolve into a pile of sludge. Can someone CLEAR this confusion up for me. |
Dave Wilson
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 30, 2006 - 11:05 am: | |
Most operators have shut off valve so the air dryer is bypassed for the extreme weather days -10 even -20 airdryer works fine when it dipps below that you need brakesaver in your system if i just run with airdryer the discharge outlet will freeze and with 9s no air means no heat.I am learning everyday this is just what i have learned over the years operating in the north. |
truthhunter@shaw.ca
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 30, 2006 - 11:41 am: | |
Thanks Dave , that last detail helps it all make sense now. The joys of -30 weather |
Dravo
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 30, 2006 - 9:17 pm: | |
We lost a tranny on a 102DL3 due to a driver accellerating with the brake on. |
Buswarrior (Buswarrior)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 30, 2006 - 11:27 pm: | |
Hello truthhunter.
You are correct, alchohol is an air dryer desicant killer. The desicant is rendered ineffective by the alchohol, defeating the entire purpose of the air dryer.
An achohol evaporator or injector unit may be installed after the air dryer for those applications that require it.
The air dryer has a heater in its base to keep the purge valve from freezing. Many bus converters accidentally remove the source of power for the heater during the stripping stage of the conversion, leading to a frozen dryer, which gives you a disabled bus.
On the MCI's, the coach HVAC system is popularly the source of power. Leave the coach blower switch turned off at your peril!
happy coaching!
buswarrior |
truthhunter@shaw.ca
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 31, 2006 - 12:16 am: | |
B.W. without seeing what I have on my MC 8 Would you guess that my OEM alcohol injector located in the right side of engine bay might be suitable for remounting down line of my aftermarket Air dryer that was installed by the front axle, or is do I need a different style of alcohol injector ? Living in Manitoba , I think I should aim to use both systems. |
Buswarrior (Buswarrior)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 31, 2006 - 5:25 pm: | |
Hello truthhunter.
I expect that you will be able to successfully move that alchohol evaporator from its mounting on the tag fender in the right side engine room and replumb it up front after the air dryer.
Possible locations would be under the driver, in the outside compartment or in the spare tire compartment, depending on what you are doing with either of those spaces, which ever would be easier to get at once in awhile to fill the bottle.
With some luck, the fittings might all be transferable.
While you are under there, retrofit cable style drain valves into the air tanks, route the cables to an easily accessible place, so you can easily drain any accumulated moisture without crawling underneath.
happy coaching!
buswarrior |
Dave Wilson
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 03, 2006 - 11:33 pm: | |
under the driver seems to be the best location in the spare tire location is the .... end up spilling most of it ive tryed several spots the first 9 i had #600 Greyhound combo we had it mounted in the frieght erea up top with about 60 feet of steel braided air line witch didnt make much sence. Running cables to your air tanks for easy drain works real well these coaches were designed to run over pits to be be checked and serviced daily not to be crawled under. |