Question on driving with missing Brake Can

bcaddel · May 18, 2010, 08:56:25 AM

I took our MCI-7 in for a oil change and brake adjustment today at the local Petro. All was going well until it was discovered that there is air leaking out of the brake can on the passenger side drive axle. It was $1,000 for a replacement dd-3 brake can from Mohawk but a local brake shop recommended sending it to Sacramento CA for a rebuild for $450.

I opted to send it off to be rebuilt, but it will be a week before I get it back. I don't really want to leave the bus parked at the truck stop for a week so my question is, can I plug the air lines and drive the bus to the house (10 miles)? Will the remaining brakes still work fine with the brake can missing from the drive axel. The guys at the shop have already put in the plugs into the air lines to allow them to drive it out of the shop bay into the parking lot and it seemed to work fine in that short trip.

Your suggestions will be greatly appreciated.

Ed Hackenbruch · May 18, 2010, 09:05:04 AM

I would think that you can,......think in terms of having a bad air can on your bus and not knowing about it. The big difference in this case is that you do know about it so drive accordingly. Your stopping distance will be much greater so allow for it...... also keep your speed down if possible and just be a lot more cautious.

bcaddel · May 18, 2010, 09:07:59 AM

That was my thoughts, I guess my main concern would be if it would some how lock up the parking brake with the one can gone. I dont totally understand (not even close) all the safety features built into the brakes but it seems like it would be fine as long as I went slow and easy.

thanks for your responce
Bob

bevans6 · May 18, 2010, 10:11:30 AM

Can you physically drive the bus? Sure. Can you do so safely? No. Safely is defined by having all brake systems in proper operating condition, and you won't have that, so by definition you will be unsafe. Could you get to where you are going? Maybe. Could you do so legally? No. It's illegal to operate that vehicle without all of it's brake systems in proper operating condition. Would I do it? Not in a million years. Would I have done it when I was 20 years old? Without a doubt! I was young and stupid then, I am old and wise now...

My advice is get some diaphragms and rebuild it, but you don't have it anymore, you sent it away. But I honestly wouldn't drive it without a can on a drive axle. Buses get most of their braking force from the drive axles.

Brian

kyle4501 · May 18, 2010, 10:53:20 AM

Moving in the parking lot is not the same as moving down the road. Then there is the difference between known & unknown deficiencies (& the resulting legal issues).

I'm not concerned so much about your abilities to handle the bus on a short ride home with out brakes on one wheel. My concern is how are you going to handle the situation if an idiot's actions require full braking action from you? Probably won't be an issue, but 5 out of 6 survive Russian roulette . . . .

If it were me, I'd ask the local police if they could provide an escort so it could be safely driven home at a slow speed. Maybe they could suggest the best time for such a move (lightest traffic).

I always sleep better when my stuff is close.

BG6 · May 18, 2010, 10:55:54 AM

Only YOU can answer that question, and only after asking a few others.

What is the terrain between your house and the truck stop? Any downhill stops (or uphill, which will be downhill on the way back to get the repair done)?

Which can is is? How much of your total braking does it provide? If it's a front can, NO REPEAT NO -- you get more braking from the front, AND it affects steering.

How does your coach stop with all of the brakes working right? Does it feel like you have a lot of extra, or are you wondering when the thing will finally stop?

If everything looks like a GO, then take it slow and plan on double the normal braking distance. It's better to creep up to a stop than to roll through one.

However, if ANYTHING looks like a NO-GO, then pay attention. You are worried what might happen if you leave it ten miles from home for a few days -- that's nothing compared to discovering that you SHOULD have left it there.

In flying, we say that it's better to be on the ground, wishing that you were in the air, than to have it the other way around!

bevans6 · May 18, 2010, 11:15:39 AM

I'm not sure that I would actually do this, but if I had to get this bus mobile I might install a 30 sq inch standard chamber (non-spring brake) and plug the emergency/parking and lock lines. That would give you the same braking action as a DD3-30, it would fit (which a spring brake chamber won't on the MCI drive axle) and you would have half parking/emergency brake action, which would be a lot better than none. I can buy those chambers around here brand new for under $50.

Brian

Tony LEE · May 18, 2010, 11:32:51 AM

Quote from: bevans6 on May 18, 2010, 11:15:39 AM
I'm not sure that I would actually do this, but if I had to get this bus mobile I might install a 30 sq inch standard chamber (non-spring brake) and plug the emergency/parking and lock lines. That would give you the same braking action as a DD3-30, it would fit (which a spring brake chamber won't on the MCI drive axle) and you would have half parking/emergency brake action, which would be a lot better than none. I can buy those chambers around here brand new for under $50.

Brian

might be cheap, but very difficult to fit on an MCI without major alterations. If it were that easy, many of us would do the swap.

Iceni John · May 18, 2010, 12:26:44 PM

Quote from: BG6 on May 18, 2010, 10:55:54 AM
If it's a front can, NO REPEAT NO -- you get more braking from the front, AND it affects steering.

On cars, motorbikes and bicycles the front brake(s) provide about two-thirds of the vehicle's total braking capacity. My (often befuddled) understanding is that bus and truck brakes work more equally, maybe with more braking from the rear axles(s). Am I completely wrong in this regard, or slightly wrong-ish, or what?

John, happy to brake with tradition

bcaddel · May 18, 2010, 12:35:24 PM

Thanks for all the input, I just got the bus home and it was a non event. The brake seemed to be almost as strong as normal and I took it nice and easy. There is no doubt it is better to have everything on the bus and working but I felt the risk/reward was acceptable in this situation so I took her home and will hopefully be driving it back in a few days to have the new brake installed.

Anyway thinks for the responces and helpful advice.

Ed Hackenbruch · May 18, 2010, 01:09:15 PM

Glad you made it ok. Triggered a memory of almost 40 years ago of being at a party up in the woods and a friend lost the brakes on his 65 Plymouth Valiant. Didn't want to leave it there, (20 miles from home ) and he was too impaired to drive it.......so i did.

We used another guy's 56 Ford to ease me down the hills, (2) and stop me at stop signs (2). Worked well too,.... until we got a block and a half from home.

bcaddel · May 18, 2010, 01:15:05 PM

Ed
I was invisioning the 56 Ford in front of you to give you something to bump into to stop. Then the more I thought about it, that didnt make much sense, the Ford must have been in the back holding you back with a chain or something. What happened in the last block?

Ed Hackenbruch · May 18, 2010, 05:49:11 PM

No Bob, the Ford was in front of me and we would just ease into each other for the hills and the stop signs. You shoulda seen their faces though the first time i passed them on a long straight away. I waved as i went by and wouldn't let them pass for a ways.

Nobody rode with me so i took a bottle of wine with me. I finished it before we got to town. The last couple of blocks in town to the house had 3 90 degree turns and the street there turned into gravel. Ummmm, we always slid around the corners.......i slid a little too far and found a tree.

Chopper Scott · May 18, 2010, 08:08:52 PM

Glad it was uneventful and sorry that your original question got hijacked by the safety police!

Please make sure you post back about if it's ok to drive it back to get the can put back on.

buswarrior · May 18, 2010, 08:11:33 PM

There are the things one might do to get off the road and to a repair facility... but then leave that sanctuary in a compromised configuration?

oh well.

Hypothetically speaking, I don't see why a type 30 service chamber wouldn't fit in where a DD3 goes. Brian's theory was sound in suggesting that substitution. At least there would be proper brake action at that brake with the brake pedal.

Of course, for a permanent retrofit, there's no parking feature, and a spring chamber won't fit, so it's only good for a talking point around this thread.

As for front/rear braking... wherever your biggest/strongest brake parts are, is where you do more of your stopping. These parts will be found where the weight is during a stop.

There is not the same loading of the front axle under braking in a coach as in our autos.

Some centre of mass, wheelbase, suspension, physics reasons.

So, the drive axle does a larger share of the stopping.

happy coaching!
buswarrior