How did this bus get stuck on such a modest incline?

Marceps · 03-29-2021, 08:09 PM

I wouldn't even think twice before mounting such a shallow incline. How do you folks reckon this “THINK” bus got stuck?

Rivetboy · 03-29-2021, 08:51 PM

Air suspension failure.

kazetsukai · 03-29-2021, 08:58 PM

The driver _might_ have made it if they took the incline at the most shallow angle possible instead of head on, I can't tell. Either way even if they made it without bottoming out at the rear, they would have bottomed out in the middle after the front wheels cleared the peak.

You have to know what you're doing, or rather know and be conscious of the limits of the vehicle, to drive something like that.

Mountain Yawp · 03-29-2021, 09:21 PM

Bummer of a day. I often wonder how buses like mine (anything over about 35') get anywhere, yet they do. I still need lots of miles and practice before I will feel confident with where my bus can go. Better safe than sorry for now.

CHEESE_WAGON · 03-29-2021, 11:16 PM

Not an air suspension failure. The sharp rise on the front caused the frame to act as a fulcrum, causing the rear overhang to drop suddenly and dig in to the pavement.

When this happened, the frame pulled upward, and when it did, unloaded the suspension. When the suspension ran out of travel, it pulled the drive axle (the more forward of the rear two) upward as well, pulling the tires off the ground just enough to cause the drive tires to lose traction, as the drive axle needed to go down further before it could go up the incline. Kind of like high-centering any conventional vehicle on snow. And this could happen to a skoolie just as easily, so be mindful of the physics here.

On these buses, the rearmost axle is there only for support of the engine/trans for weight distribution purposes, it is not a drive axle. This was a ground clearance problem that caused a traction problem. Without such a rear overhang, it might not have happened.

However, with this bus being built the way it is, I'm not even sure taking this incline at an angle would have made a difference. Not much different than trying to drive up a steep driveway. Bleeding suspension air, driving some wedge-shaped blocks under the drive tires, then re-pressurizing the suspension might have helped it get going again, depending on how bad the rear overhang dug into the pavement. Basically the idea would have been to raise the rear of the bus sufficiently so that it did not drag or high-center the rest of the way.

Be aware that a skoolie can and will do the same if the front end rises sharply and quickly enough in this fashion. Any rear-drive vehicle with the wrong combination of wheelbase and rear overhang can and will high-center its drive tires. Something to be mindful of.

This is also something to be aware of when going under bridges with a dip in the road. Just because you're clear going in doesn't mean you will be going out the other side. That dip combined with your wheelbase can make your clearance (ground AND roof) disappear in a hurry.

Oscar1 · 03-30-2021, 12:48 AM

That’s a great point on the bridge thing there Chesse, if you’re coming out and still going in it might be a big problem!
Thanks

Sehnsucht · 03-30-2021, 05:45 AM

I'm not even sure the tail bottoming out is part of the problem because there's not a lot of travel in the suspension of a motorcoach anyways so when the tag axle is fully tucked and the drive axle is fully extended there's not enough weight on the drive tires to move the vehicle. I have this occur quite easily on my semi truck which is the same 6x2 configuration with the sole drive axle being the center one. The electronics will try to compensate automatically by dumping the tag axle air and fully inflating the drive axle to shift as much weight to the drives as possible but the reality is there's maybe 6 inches of travel in the suspension. This situation is even worse because of the long, long wheelbase - look at how much further he'd have to travel before the drive tires even begin to climb the grade and regain traction.

School buses have one advantage but two disadvantages like this type of motorcoach... A single rear axle means you don't have the situation of fighting a tag axle but school buses have so much more overhang that can drag and also there's almost no flexibility along the frame and suspension if you get into an off-camber situation. So unless you happen to have a locking rear differential on a school bus, just getting weight off one rear tire is pretty much the same scenario, you're stuck with the light wheel spinning but going nowhere.

cadillackid · 03-30-2021, 06:33 AM

that giuy didnt stand a chance.. even if he somehow made it past, he was going to high center at the top. the only way that bus was getting in there wouldve been to hit it diagonal curbing the left side on the sidewalk and then curbing the right side at the top.. .. my little red bus rides low in comparioson to its wheels.. I have to watch every driveway I go in so i dont do this and its a shorty.. it just has small wheels and sits low.. motorcoaches have super low skirting in relation to the axle for the luggage bays

kazetsukai · 03-30-2021, 07:12 AM

Depends on the bus really, how much this is a problem. My rear overhang must not be that bad, I've done some pretty gnarly hills that made me nervous going up (and down!). My uncle's driveway, I was sure I'd scrape the road on the way in/out.

I also went over a low water bridge that had a dip in the beginning then a sharp incline under two car lengths later. Worst possible combination, went really slow prepared to back out of it. Somehow made it.

Crown_Guy · 03-31-2021, 07:17 PM

Everything said above. dragging and digging in the rear bumper, unweighting the drive axle causes the leveling valve to dump air making it worse and removing any traction from the drive axle which is as said the middle one. Thus anchoring the rear end for good, too bad so sad. Also looks like it would high center at the top of the driveway. Trying to come out again would do the same thing so he's screwed going in and coming out.

Bottom line for me is this is a new and or very inexperienced driver. Probably both. I never attempt these kinds of drives and always park on the street curb and make them come to me. In general, any kind of parking lot is to be avoided for many reasons anyway, like the concrete curbs they love to build in them where the Coach can't make the turn, to cars parking in wrong spots so I can't make a turn, way too many reasons, so I avoid parking lots like the plague, and these kinds of entry/driveways. So Sorry, you get to walk to the bus, I'm not going in there.

And yes I've managed to do that exact thing here on a driveway that looked perfectly OK and very flat going into a bus turnaround at a school. It wasn't, and the dip at the curb was enough to hang the MCI just like this. School buses managed it fine, just not the MCI 45ft DL I was driving, Oopsie. It took a big-rig wrecker to get the thing unglued again. Coaches belong on the flat, paved, level streets, Period. Anything else and you take your chances with Senor Murphy, and he's a bastard, and loves to make our lives miserable.

Crown_Guy · 04-09-2021, 11:06 PM

Sorry. But I just can't resist this. Years ago I drove Crowns into the most insane imaginable situations in Commercial Service in and out of the ugliest roads and driveways to access various group camps all over the State. I don't have any pictures available to show so it comes off as B.S... Until now..... Last week I picked up the Crown I've been driving in Service for the last 5 years, where it was languishing, on the top of a little ridge on private land in Topanga Canyon, all due to the forced Wuhan Flu shutdown killing all transportation services.

I thought the pics of the location and the driveway back down the hill would be of interest to show what a Crown can do when required. The pilot can influence this too, of course, if not done correctly it would be very bad, but then that might be considered bragging too. Enjoy. And allow me my little indulgences since I don't get the chance to do this kind of acrobatics much anymore. Brings back many fond memories though.

After this, the winding Canyon road back to the freeway was very typical and almost boring.

This Crown will be available to buy as soon as I do the Title/Convert paperwork and do a little cleaning to get it ready to present here. Keep an eye out.

Simplicity · 04-10-2021, 01:19 AM

When we route our buses we always take into consideration turn radius, rear overhang, wheelbase, skirting/storage bin ground clearance, etc.. It's pretty funny some of the routes we have to take due to all the size/height limitations.

The "Think" bus has a super long wheelbase, long rear overhang and low ground clearance. It wouldn't take much to get it hung up.

Our clown buses have sooooo much front end hang-over (very short wheelbase and very long body) that it's really common to scrap coming out of a pretty regularly sloped parking lot onto a street if you approach it straight on. At a diagonal, not such a big issue.

mmoore6856 · 04-10-2021, 08:33 AM

all the more reason to put a manual bypass valve in your air ride system. you can also use it to increase drive wheel weight in icy conditions

Sehnsucht · 04-10-2021, 10:51 AM

Quote:

Originally Posted by mmoore6856

all the more reason to put a manual bypass valve in your air ride system. you can also use it to increase drive wheel weight in icy conditions

Nowadays these electronic controlled air ride suspension systems will do that automatically but the limitation is still the amount of suspension travel. I've had more trouble with the 6x2 semi tractors simply because the range of travel of each axle is not that much and if you stretch one fully up and the other fully down you've already 'bottomed out' in obstacles as simply as potholes! Rutted muddy trailer drop yards are the worst! Motorcoaches are even less intended for this kind of off camber terrain.

mmoore6856 · 04-10-2021, 11:21 AM

Quote:

Originally Posted by Sehnsucht

Nowadays these electronic controlled air ride suspension systems will do that automatically but the limitation is still the amount of suspension travel. I've had more trouble with the 6x2 semi tractors simply because the range of travel of each axle is not that much and if you stretch one fully up and the other fully down you've already 'bottomed out' in obstacles as simply as potholes! Rutted muddy trailer drop yards are the worst! Motorcoaches are even less intended for this kind of off camber terrain.

I drive also but i work for a company that paved its lots with concrete so we dont deal with that

Brad_SwiftFur · 04-10-2021, 04:35 PM

I observed a truck driver do something similar with a steep driveway vs. flat road. Long story short he high-centered the trailer's landing gear on the pavement and got hung in the middle of the road. Cops came, called a wrecker, but the driver was like "Don't bother the wrecker, watch this." He crawled under the truck, disconnected the air ride valve and pushed it up, causing the air bags to inflate. He was then able to complete his turn and reconnect the air ride valve, returning everything to normal. No wrecker necessary, though I believe he still got a ticket.

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