Leveling MH with wood under the tires.

[gemini5362]

Originally Posted by Ramblin

Consider this image of a typical backhoe stabilizer. Notice the small ram as compared to the massive leg structure. The LEG isolates the ram from ANY lateral movement. The ONLY stress on the ram is linear.

On an RV, the RAM is the ONLY STRESSED MEMBER, and IS NOT ISOLATED from lateral movement, except to the extent that tires on the ground isolate it. I contend that lateral movement can, and has, caused RV jacks to bend and become unusable because they are not designed to withstand much lateral stress.

Hope this clears things up.

If that is how the backhoe jacks work I can see your point. I told you I was not an expert with them and have only rented them a couple of times and been a long time since that ( I found out that mini excavators are more fun to play with.

I still ask the same question has that ever happened to anyone where they have had to replace a jack because it was bent from lateral movement. ( and not because you tried to drive while it was down )

[gemini5362]

Originally Posted by ShapeShifter

Short and sweet - A very good summary!



There are a few subtle differences, so one can't really say that it's not a problem to lift a motorhome off of the ground just because a backhoe does that.

The motorhome has a hydraulic ram with a smooth plate attached to it, and is primarily designed to have only compressive (no lateral) forces. On the other hand, a backhoe has a large steel arm that is hinged to the backhoe frame. It is this arm and hinge that is intended to take most of the lateral forces. The hydraulic ram angles between the backhoe frame and the pad on the heavy steel arm, and mostly supports the weight of the backhoe, while most of the lateral forces are absorbed by the arm and hinge.

Furthermore, on the backhoe, the pad that contacts the ground is not smooth, but has a "tooth" on it that sinks into the ground to help stabilize the backhoe and prevent the pad from slipping, the motorhome doesn't have this.

So while both have hydraulic rams that supports the weight, the details are quite different. One is designed to lift the equipment, stabilize it from movement in all directions, and prevent slipping; while the other is much less robust and designed only to support vertical weight. You cannot make assumptions that the motorhome jack will safely do everything that the backhoe jack is designed to do.



Only partially true, I left out some details. Everything started out normally, and after the initial leveling attempt the rig was nice and level, but one of the rear wheels was raised up into the air. It was while trying to lower the rig from this stance (so that he could put boards by that wheel and drive up on them) that things went horribly wrong. It's not clear whether the jack jammed first and that triggered the controller to go haywire, or if the controller went haywire first and jammed the jack. Or perhaps the jack jammed and the operator pressed too many buttons too fast trying to un-jam the jack and that confused the controller? (The husband was at the controls that day, and he has limited experience with that relatively new coach. The wife usually goes to dog shows alone for 90% of the trips. I think this was only the second or third trip in this coach for the husband.)

Whatever the sequence of events, raising the wheel off of the ground may or may not have caused the event, but once it happened it certainly made the situation worse.

It sounds like you don't want to believe that the experiences of others will have any impact on you, and you would like to continue to occasionally raise your axle in the air. If that's what you want to do, please feel free to do so. I truly hope you never run into trouble with it. But prudence would seem to dictate that it would be better to avoid the situation if possible, as that's the best way to prevent it happening to you.

Good luck! (And I really mean that, I'm not being sarcastic.)

Actually if you look at my posts you will see that I do not like to do it but do not think that I have a vaild reason for not doing it. I have moved camping spots when I could. I have turned the motor home around to not lift the back off of the ground. I move around on the parking site to try and get a space that is more level. What I do not do is carry a lumber yard around in order to level wheels and then go from there. If I was going to do that I would have stayed in my fifth wheel for a whole lot less money.

As far as not believing situations. I have asked if that has happened to any one else. You yourself in your second paul harvey post still admit it could have been the jack sticking that caused the problem. or the controller controlling the jacks caused the problem or the husband not being familiar with the equipment caused the problem. I do not recall in your original post whether you said the jack was bent as the outcome or just the window was cracked. I am just curious if someone has had a bent jack that had to be replaced because of having the wheels off of the ground. That is a pretty simple question.

I looked at the diagram ramblin put in his post and see what you are talking about with the backhoe. I said I was not expert on backhoes and I can see the difference in the way they are made.

[Ramblin]

Originally Posted by gemini5362

If that is how the backhoe jacks work I can see your point. I told you I was not an expert with them and have only rented them a couple of times and been a long time since that ( I found out that mini excavators are more fun to play with.

I still ask the same question has that ever happened to anyone where they have had to replace a jack because it was bent from lateral movement. ( and not because you tried to drive while it was down )

A quick search of this forum should turn up some examples. One I found even had a poster that says his manual specifically says that NO wheels should be raised off the ground when leveling.

[ahicks]

Bent jacks (and jack mounts) do happen. I think everyone has to agree on that. Are you assured of a bent jack when you lift a wheel off the ground? No, not likely, but it's not real hard to imagine how doing that might increase the chances of having that happen?

Bottom line, every off level jacking situation is different. Make your call based on the situation, and live with the results? Chances are pretty good the 'tire in the air' police will never notice (or care?).

[KSCRUDE]

I don't carry blocks or wood of any kind. The jack pads are plenty big so no need for blocks. Did that with the fiver and them days are gone. I never lift the drive wheels off the ground but have had the fronts off a inch or two before. Don't like to as then it makes for a big first step to get on the stairs. If the site is pretty level, the rig will sit pretty level on its own and I may not even drop the jacks for a night or two stay. The rig doesn't shake or bounce much at all.

[ShapeShifter]

Originally Posted by gemini5362

Actually if you look at my posts you will see that I do not like to do it but do not think that I have a vaild reason for not doing it.

That's good to hear. I guess we're more alike than different, except that I can't think of a valid reason for dangling a tire - maybe after all it doesn't hurt, but I can't see that it would be good, and it's easy enough to avoid.

What I do not do is carry a lumber yard around in order to level wheels and then go from there.

Don't need a whole lumber yard, but some blocking can be helpful in many situations, at least in my case where a majority of the time I'm not at a campground. Without some blocking, there are many times I would be very unlevel, sinking into the soft ground, dangling a tire, or any combination of all three. If you have the luxury of always being in RV parks with firm level sites, or can move if you get a bad site, then it may not be as important. But I won't travel without some blocking, and it looks like I'm not alone.

I do not recall in your original post whether you said the jack was bent as the outcome or just the window was cracked. I am just curious if someone has had a bent jack that had to be replaced because of having the wheels off of the ground.

You're right that I don't know the exact cause of failure: we were all hungry and wanted to eat dinner, so we were more worried about getting the jack retracted rather than performing an engineering fault analysis (not to mention that none if us was qualified to analyze it properly!) I also don't know if the jack had bent, as I wasn't there when they made the repairs and replaced a lot of parts. All I know for sure is that once the jack was retracted, they didn't dare to try and use them again on that trip: instead they used the lumberyard that they carry (plus a couple pieces borrowed from me) to put under the wheels and get reasonably level without the jacks.

[gemini5362]

shapeshifter and ramblin now that we are more or less on the same page let me ask you a question. I do not like the idea of using a lot of space carrying wood around. I think there may be a better way to do the same thing and want your advice. There is a company that sells air bags to level 5 ers. You stretch the flat air bag on the ground drive on to it. Then air it up until it is level. I saw an article on how to make one of those and they are not hard to make. I used it on my 13000 pound 5er and it worked well. I had it up once for a week and did not have it lose any air or have to relevel the coach. Could you use one of those to support the wheels when you are leveled with the jacks ? You can roll them up and they take up less space than pieces of wood.

[ShapeShifter]

Originally Posted by gemini5362

Could you use one of those to support the wheels when you are leveled with the jacks ? You can roll them up and they take up less space than pieces of wood.

My first thought was whether these air bags can handle the extra weight compared to a 5er, but then I realized you're talking about using them after you've leveled with the jacks. I suppose you could do that under one front wheel, to fill the gap and raise it a bit to take the strain off of the lower bump stops (or whatever it is they use to prevent the front axles from totally dropping off the coach.) But I wouldn't do it with rear wheels, as I doubt that they have any shear strength to prevent lateral movement - once inflated I would think that the top surface (supporting the wheel) would be free to move in any direction relative to the bottom surface (contacting the ground.)

You said you're concerned about space, and don't mention weight, but have you considered those light weight plastic stackable blocks?

Originally Posted by KSCRUDE

I don't carry blocks or wood of any kind. The jack pads are plenty big so no need for blocks.

Good for you, you always get good firm sites. I have 18 inch square blocks, and there have been times where I've had to dig them out of the soft ground when leaving -one place was so soft they were buried almost 6 inches! There are times I wish I had 24" or 36" blocks to spread the load!

[Ramblin]

Originally Posted by gemini5362

shapeshifter and ramblin now that we are more or less on the same page let me ask you a question. I do not like the idea of using a lot of space carrying wood around. I think there may be a better way to do the same thing and want your advice. There is a company that sells air bags to level 5 ers. You stretch the flat air bag on the ground drive on to it. Then air it up until it is level. I saw an article on how to make one of those and they are not hard to make. I used it on my 13000 pound 5er and it worked well. I had it up once for a week and did not have it lose any air or have to relevel the coach. Could you use one of those to support the wheels when you are leveled with the jacks ? You can roll them up and they take up less space than pieces of wood.

I think the purpose of keeping tires on the ground when leveling is to minimize lateral movement of the coach against the jacks, and not so much to support the wheels. I therefore think that anything you do towards that end will help minimize the possibility of jack damage due to lateral movement. In the case of your air bag solution, if they provide lateral resistance then they will certainly help.

My coach moves around a LOT when on jacks if the wheels are high off the ground. Enough so that I find it necessary to block up the wheels. Others may have different experience. As another poster mentioned, you make your decisions and live with the results.

Personally, I carry four 'ramps' made from 2x8 material approximately three feet long, and four 'pad blocks' made from 2x10 material. The ramps stack up on top of each other in the back of a basement bay, and the blocks do the same. They take up very little room and provide good stability for when I must raise my wheels off the ground to level.

[JohnT]

Pretty interesting read and thanks for the responses.

I created a little chart that shows how many boards I would need to level the coach front to rear. If the site looks unlevel, I get my 24” level out and measure the height to get level. For every 1/8” of vertical on the short level equals 1.4375” vertical at an axle. A 2” x (x” wide) is close enough. My limit is a ½” on the short level as this is 5 ¾” under one axle. Then I start looking to reposition on the site or ask for a different site.


My experiences have been on fairly level sites and have never needed more than the equivalent of 2 boards. Parking in a field will be a new experience.

Thanks

[ShapeShifter]

Originally Posted by JohnT

Parking in a field will be a new experience.

And a pretty "interesting" experience that can be!

This site was pretty level, but as you can see from my tire tracks it was pretty soft:

That was just after I got to my assigned parking space, and I was still in the process of setting up (let the dogs out first, then take the picture, then finish setting up.) You can be sure I had quite a few blocks under the leveling jacks to spread the load. This is a fireman's field behind the fire house.

But the soft ground here wasn't the interesting part, it was getting to the space. The "driveway" to get back to that spot was really soft:

Those are my tire ruts after my first attempt to get back there. Note the guy walking away with the shovel, he had just finished up filling in and smoothing the ruts as much as possible.

In that picture, I made it as far as the patch of saw dust before bogging down to the axles. I didn't think about it, but I had the automatic traction control on (which is on by default) and when it sensed the tires slipping it did me a "favor" by cutting the engine power, pretty much guaranteeing that I would get stuck. I got pulled out by one of the fireman's F350 4x4s, and on the second run I turned off the traction control and just gunned it to keep the momentum going, and I made it through.

My space was all the way in the back just beyond the white popup tent all the way in the distance - I was standing next to that popup when I took the first picture. I'm thankful it was a straight shot and I didn't have to slow down and turn to go down one of the side alleys. I didn't even bother trying to face the same direction as the others, I just pulled in straight - I was the last space on the row so I didn't have to worry about my awning interfering with the next guy's awning. And with no services of any kind, I didn't have to worry about being near the utilities.

But all of this is getting off topic. Back on topic: in conditions like this, carrying a bunch of wood blocks is not a personal preference, it's a necessity!

[JohnT]

Originally Posted by ShapeShifter

And a pretty "interesting" experience that can be!

This site was pretty level, but as you can see from my tire tracks it was pretty soft:

But all of this is getting off topic. Back on topic: in conditions like this, carrying a bunch of wood blocks is not a personal preference, it's a necessity!

Thanks. I will also be packing 50' of plastic snow fence.

[ShapeShifter]

Originally Posted by JohnT

Thanks. I will also be packing 50' of plastic snow fence.

What's that for? A traction aid?

If so, an interesting idea. The above was a few years ago. I got stuck again earlier this year in a similar situation in another fireman's field. I tried hammering a friend's ramps under the rear wheels, but the tires just spun and wouldn't ride up them. The ramps sound like yours. These had 45 degree cuts on the leading edges of the individual stacked boards, but they didn't help.

If I had something that would've been easier to get under the tires, I might have been able to back out since I wasn't in as deep as the above pic, and I was only about 20 feet from the road. In the end, I had to rely on one of the fireman's brush fire off-road trucks to pull me out once again.

Interesting coincidence: the friend I borrowed the ramps from just happens to be the same one parked next to me in the Dutch Star in the first picture.

[JohnT]

Originally Posted by ShapeShifter

What's that for? A traction aid?

Yes it is. I've seen others use it.