driving with one wheel/tire/axle off the ground

[hndrsonj]

I think what JROU111 did is what kenny was talking about earlier. By not having tires (weight) on the fwd axle, all the torque from the driveshafts are going to cause the fwd rear axle to want to move around alot even though it is chained up (probably the noise he was hearing). If it was the rear most axle there would not be anywhere as much torque affecting the last axle, it would just turn freely. (not meaning to start the disagreement up again though).

 

[jesusgatos]

I was not disagreeing with anyone. I was asking for a more thorough explanation of exactly what the problem/s might be because I honestly don't understand.

 

[hndrsonj]

I think the fwd axle with tires off will try to slide the whole axle left and right and that's where the problem is with the fwd one.

 

[jesusgatos]

Hmmm, I don't see how. The axle would still be located by the three-link and panhard bar, so how would the ale move from side-to-side?

 

[mudguppy]

and it has an open diff. and there's no pressure exerted on the axle to ground. and the tire is flat.

i still don't see it.

 

[jesusgatos]

The only problem I could see would be if one wheel/tire wasn't spinning and the other wheel/tire had to spin twice as fast. I can see how that would be kind of hard on the spider gears, but I'm not sure why one wheel/tire wouldn't be spinning. Seems to me like they would both just freewheel along with the rest of the drivetrain. Can anyone that thinks it would be a problem please elaborate?

 

[jesusgatos]

I redesigned the lower bracket and tool the files to a local sheetmetal shop to get a quote, but before I can have any parts made I need to decide what size/type of chain to use. Is there any chain that is common the military applications that it would make sense to use here? Maybe like the winch chain, or ____?

 

[cranetruck]

The Gama Goat runs without one or two tires by design and carries no spare.

 

[jesusgatos]

Cool. Thanks for sharing.

 

[DodgerRoger]

Working as a mechanic I have chained up axles a few times and seen it done often by others, I would say that to get you moving to a place to fix it no problem. I second the idea that the axle to chain up would be the middle one, so that you keep your long wheel base and as much stability as possible. I wouldn't worry about the spider gears, the torque is going to go to the path of least resistance. Even hanging in the air there should not be enough of a difference to really matter, if there is the real problems will show up when you put power on the ground. My mind wanders around some crazy idea of some pin in air bags for the rear axle so that when required you could slip them in and hook them into the trucks air, pushing down on the rear will lift the front and carry the load. With some leveling valve trickery you could lift the middle and pull the tires, then hook up leveler and let it ride on air till you get all the tires fixed. But then again Im a dreamer.

 

[jesusgatos]

Airbags on the rear axle wouldn't lift the middle axle.

 

[Adrian A]

Running it as a super-singled 6x6. I'll have one spare, and will use that if I get a flat. If I get a second flat, that's when I'd need to chain-up the axle. Sorry, was I unclear about that?[/QUOTE]Yes! This is a viable option.

 

[gringeltaube]

Airbags on the rear axle wouldn't lift the middle axle.

Are you so sure about it...??

G.

 

[RodUSMC1962]

For every action there is a reaction.

 

[Hainebd]

In an Emergancy it could be done. Chain up the blown wheel bearing hub or ? Flat to frame and drive slowly. On road I would not due. The deuce rear suspension balances the load between the rears. The spring pack is so heavy duty I doubt it springs much. Now with one axle tied that will generate load on the chain on every bump. Plus in turns and torque from drive shaft things are going to move.
If you want to do make a tag axle on bags. No power just extra tires to carry weight. But why. Just run it. I had three flats and never knew it. Tire ran fine flat. 12 ply. Singled out. Why. Now you will also lose stopping power with that axle tied up. Again why.

 

[jesusgatos]

Are you so sure about it...??

G.

Yeah, that would work if the walking-beam suspension had a solid link between the two axles, but seems to me the leafsprings would allow the middle axle to stay on the ground because there's nothing pulling the middle axle up and leafsprings are made to flex and those leafsprings were designed to be loaded in compression. Really doubt the middle axle is getting off the ground, but would make an interesting experiment.

 

[mudguppy]

springs exert the same force in either direction. the spring pack would lift as much as the spring rate allows, albeit only the couple/few springs that would be captured in the retaining bracket on the axle. I'd bet a mountain dew it would pick it up. i, however, question whether or not there would be any sort of suspension give if using bags in the rear to pick up the intermediate axle - the bags would have to carry the weight of the rear of the truck plus the addition of the axle. also, the bags would need to have such a travel that they would push the rear upward enough to lift the intermediate AND not bottom out when the rear axle articulates upward during normal offroad suspension travel.

 

[gringeltaube]

................................there's nothing pulling the middle axle up and leafsprings are made to flex and those leafsprings were designed to be loaded in compression. ...

LOL, obviously that is a pure hypothetical scenario - just a quick drawing in response to your post #71. In reality it would be less than 8" there, since the springs do flex some, of course. But fact is, if you pushed that rear axle down the other one comes up.
For your experiment you can use a bottle jack plus some wood blocks - instead of air bags. You will find out that the spring packs are stiff enough to carry the load of the axle with wheels/tires, fully suspended. Truck unloaded, that's clear...

G.

 

[Hammer]

I did what you are talking about, it BARELY got the tire up, and I mean BARELY!
The weight of my super singles were heavy, and the spring pack has slop for verticle when you unload it, plus it is hanging by a couple spring leafs, which are not as stiff in that load direction.

BUT, it would be enough to do if you took the wheel/tire off. I wouldn't do this if you had to keep the tires on and didn't want them hitting the ground. For a flat tire, sure.

Btw, chaining the axle up enough so it hits and upper stop eliminates the chain moving around too much, but what, and where that stop is needs to be addressed.

 

[jesusgatos]

springs exert the same force in either direction...

...albeit only the couple/few springs that would be captured in the retaining bracket on the axle.

The second part of your post I quoted is correct, and conflicts with the first part of your post. Agree with the second part, but not the first. Most leafsprings are not going to exert the same force in either direction.

LOL, obviously that is a pure hypothetical scenario - just a quick drawing in response to your post #71. In reality it would be less than 8" there, since the springs do flex some, of course. But fact is, if you pushed that rear axle down the other one comes up.

For your experiment you can use a bottle jack plus some wood blocks - instead of air bags. You will find out that the spring packs are stiff enough to carry the load of the axle with wheels/tires, fully suspended. Truck unloaded, that's clear...

I understand that it's going to exert a lifting force on the middle axle, but practically speaking, don't think it's going to be enough to work the way it's being discussed here. Have a few bottlejacks that I can use to test this theory. Will take some pictures and post the results.

I'd bet a mountain dew it would pick it up.

Sure, at some point it's going to lift the middle axle, but how high do you think we'd have to jack-up the rear of the truck? Betch'a mountain dew it's more than just a few inches...