Lifting & Supporting the Bus

[GnarlyBus]

I'm getting setup to get under my bus to grease, brake adjust, etc. I've read a lot of good threads on the subject but I'd like some more input.

I've kinda been debating how to support the rear of the bus. No concrete available for me so I'm stuck with asphalt or dirt/gravel. I was originally planning on building giant heavy ramps, but now I'm considering two other options.

1. 22-Ton Jack Stands (see attached) - These have 11"x11" base plates. I'm leaning towards this option because I need to do brakes, bearings and seals in the future. Would these sink into asphalt? Also, if I had to use them on dirt/gravel would 20"x20" 3/4 ply work safely?

2. Stack of 7 2x12s ~ 20" long - Basically make ramps without the ramp and add levels as I'm jacking the rear up.

What do you think about these ideas?

Also, If I lift the rear up do I need to chain up the tag axle beforehand or can it hang with only the drive axle supported?

[daddysgirl]

IMO, those stands should work well. I use something similar, but I have a concrete bus pad. I also chock the front wheels. If you use the correct suspension points, I don't see why you should need to chain up the tag

[bevans6]

When it comes to a bus, my experience is anything will sink into asphalt, including the tires, if the temp is on the warm side.  I would just try to get the job done somewhat quickly, and use block floats like a crane truck does, usually 2' square by 3" thick, to spread the load.  It depends a lot on the quality of the paving job. Usually a well founded dirt or gravel driveway can be more stable than asphalt, which technically remains plastic.  If the bus runs, starting out with run-up blocks or ramps is a great idea.  Jacking and blocking the bus is a serious business, but if you approach it with a serious intent it's not all that big a deal.  Measure the clearance you have to work with when the bus is on the ground and the suspension is fully collapsed.  Get a jack short enough to get under the jacking point with the bus fully down - I can't tell you how many times I merrily jack up the bus and then can't get it off the jack again because I've lost clearance with no air pressure...

[richard5933]

...Also, If I lift the rear up do I need to chain up the tag axle beforehand or can it hang with only the drive axle supported?

Does the manual say anything about letting the tag axle hang? GM doesn't recommend letting axles hang by the air bags - probably something similar in your book somewhere.

One thought about your plywood... Maybe consider using marine grade plywood so that it's not as prone to de-lamination when it gets moisture underneath it from laying on the ground/gravel. I'd also want something thicker than 3/4" - perhaps double that by gluing/screwing two pieces together.

[buswarrior]

You're on the right track as far as combinations of cribbing.

Note level ground and block the front wheels... no parking brake once the tires leave the ground

It is bad form to leave the tag axle hanging, it's only the shock holding it. If it breaks, the tag can swing as far as the tire lets it.

Knocks into cribbing, whacks you, upsets the coach, scares you real bad...

None of that gamble is required. Chain it up.

Happy coaching!
Buswarrior

[bobofthenorth]

Would these sink into asphalt? Also, if I had to use them on dirt/gravel would 20"x20" 3/4 ply work safely?

The stands look adequate but I wouldn't trust them on soft ground with a single layer of 3/4 plywood under them.  I think they'd go right through the ply.  I'd go with two layers of 3/4 plywood glue laminated or better still a plywood, lumber, plywood sandwich.

[Oonrahnjay]

The stands look adequate but I wouldn't trust them on soft ground with a single layer of 3/4 plywood under them.  I think they'd go right through the ply.  I'd go with two layers of 3/4 plywood glue laminated or better still a plywood, lumber, plywood sandwich. 

      Yep, and I'd go for at least a 1/8" sheet of aluminum laminated on top.  Steel likes to slide of steel but not so much on aluminum.  It would be kinda expensive (unless you happen to have some around) but not nearly as expensive as what it would cost your widow to have the bus lifted off you.

[GnarlyBus]

Hmmm. I went to the lumber yard and priced out Baltic Birch to make some 20"x20" plates with two layers glued together. It's about $65 for a 5x5 sheet of Baltic. Now I'm kinda reconsidering using 1/4" steel plates instead. Probably wouldn't be that much more expensive. Think 1/4" would do the trick on dirt?

How much stronger is 1/4" steel than Baltic double thick I wonder for this use.

For my work that I need to do under the bus, I'll be on asphalt.

For the work I need to do on the axles (wheel seals, brakes, etc.) I'll likely be on gravel or dirt. For this, I shouldn't need to get under the bus at all so I'm starting to think I should just crib it up with 4x4s or 4x6s real good.

Thanks for all the replies.

[6805eagleguy]

I would want 1/2" plate on dirt or asphalt.
1/4" is kinda weak for me...

[GnarlyBus]

I would want 1/2" plate on dirt or asphalt.
1/4" is kinda weak for me...

That's like 80 lbs!

[6805eagleguy]

Yes but 1/2" won't bend 1/4" will bend on soft ground IMHO

But then maybe everything I do is overkill

[buswarrior]

Is this heading in a bit of an excessive direction?

We're only holding up one end of a bus...?

happy coaching!
buswarrior

[GnarlyBus]

Yah I'm all for safety but it's starting to sound more like we're trying to bridge concrete with steel and park the bus on it. I really think the asphalt I'm gonna be on will be fine with the 11x11 foot pads of the jack stands. I figure I'll add some 3/4" ply to spread out the weight a bit.

The drive tires are about a 12"x24" footprint on each side. Seems like getting close to that would be sufficient.

I'll crib up under the frame as a secondary security.

I do appreciate the input. Reading old threads on this topic people have a tendency to "one up" on each other on safety until someone suggests a pit! Nobody mention railroad ties either or all heck will break loose!

[Jim Blackwood]

A reasonable safety margin would be to expect one jackstand to hold up 20 tons. That's the full loaded weight of most buses so it should never go that high but with side loading and other odd things it really gives you about a 2:1 safety margin. (Expecting one stand to hold the full weight of one end is reasonable, rational and will probably happen.)

Can you simulate what 20 tons will do to your cribbing? Yes, if you have access to a hydraulic press. Worst case, the cribbing will be supported at opposite ends of the long axis. Will it support 20 tons that way? Then how much weight per sq. ft. will the ground support? You can find loading charts for concrete, asphalt, dirt, and probably gravel. Find a happy medium that allows a short span but gives adequate surface area, and then never, ever try to use it on wet ground.

Jim

[GnarlyBus]

Good food for thought. Only note is that most jack stands are spec'd as a pair. So 22 ton working load for the pair evenly distributed.

I think i have a plan now.