Disabling Leveling Jacks

[gemini5362]

Originally Posted by ShapeShifter

I completely agree up to this point.



No, it's not exactly the same. In one case you are using a jack that is attached hard to the frame. If not done correctly, it's very easy to twist the frame. Furthermore, when using the leveling jacks, you must raise the corner of the coach far enough to take all the slack out of the suspension so that the axle is dangling from the stretched out air bag and shocks. Then you must lift the corner a little further to raise the tire off the ground. You will raise the corner of the coach by the distance that the wheel is raised, PLUS the distance it takes to fully extend your suspension to the limits.

With the proper jack for changing tires, which is placed under the axle, the axle is being lifted just enough for the tire to clear the ground. The suspension is not stretched out, but perhaps it is compressed a little more than normal. At the worst case, the ride height control valves will maintain the relative distance between the frame and the axle. In either case, the most the corner of the coach will raise is the distance that the wheel was raised, maybe even a little less.

It is NOT exactly the same situation. The difference is how far the suspension must stretch before raising the wheel off the ground.



Proper leveling procedures will prevent twisting, and damage to the windshield, improper procedures can cause damage. If the tire technician is not trained in the proper procedures for using the jacks, there is the possibility that they will do it improperly. The proper procedure is not always intuitive, although the control panel often makes it seem that it is. On mine, it seems like you would just press the button for the corner you want, but if you don't lift the front several inches first, you will very likely tweak the windshield. My coach and jack manuals are very adamant about that point, but the tire technician is unlikely to know that.

If the proper jacks are used under the axle, the body movement is minimized, any forces on the frame are applied through the compliant suspension (not on the non-compliant jack mounted directly to the frame) and the changes of damage are minimized. And if there is damage to the coach, it is clearly from the tire shop's equipment and methods, and there should be no question who is responsible for repairs.



Again, not the same scenario. When working on the tires and other coach equipment, there can be side loads applied to the jacks, and they are not designed for this. Furthermore, a tool could accidentally contact and loosen or damage a hydraulic line, causing the coach to drop. This is even more likely if you are working under the coach, and not just changing tires. Finally, another person could accidentally operate the leveling controls.

None of this is a serious concern when camping. I agree that the odds of a jack dropping the coach are low, but if it happens while camping, the consequences are low: you just re-level. But if you are working on the coach, especially under the coach as some have mentioned, the consequences can be much more severe. Are you willing to bet your life on the jacks not dropping? Is your life not worth the few minutes it takes to get the proper supports set up? It only takes one failure or accident to really ruin your day (or life...)



I've seen it myself, and I agree its not smart. Especially when it's the rear wheels. I've not seen every coach and jack owner manual out there, but every one that I have read says that you should not use the jacks to raise the tires off the ground.



Once again, we are in complete agreement.



I also agree... until they end up doing some damage and claim that it wasn't their responsibility. They may be able to make a case if they are using your jacks, perhaps they already had the problem before you got there? But if they use their own equipment, and they cause damage, there is no question that they are responsible for any repairs. Taken to extremes, if an accident should happen and the tire technician is injured or killed, they could bring a suit against you saying your jacks caused the injury. If they use their own jacks, they can't hold you responsible.

In my last post, I linked to an existing thread where the tire shop caused damage to a jack system. The blame was not clear-cut, even some of the posters on that thread blamed the jack system and the RV owner and not the shop. It's not a big deal until a situation like that happens, and then it's too late. But it simply can't even become an issue if they don't use the leveling jacks in the first place.

If you don't care what a shop does to your coach, and how they do it, then ignore this thread and move on. If you do care, the reasonable and most low risk approach is to tell the shop to use their own equipment and leave your jacks alone. Why is it so bad to want the shop to do it properly and safely?

I see it as being very similar to having a contractor to your house to do some work. Are you going to have him use your ladder and tools, or do you expect him to be properly equipped and have the right tools, and use them properly? If you do loan him your ladder and tools, are you prepared to accept liability if he is injured while using them? If so, then go ahead and let them use your leveling jacks - but please don't post here if there turns out to be a problem.

Like you I am in agreement with part of your post. First of all let me emphasize that I do not believe in having the shop use your jacks for raising the vehicle to change tires. I believe they need to use their own jacks and jack stands. You mentioned liability if the shop uses your jacks they do so at their own risk. I am sure most of the people on this forum are older and most of us know that a good attorney can argue a case from either side and make their point. I do at least one arbitration a month where I argue contracts. I can literally argue either side with no problem in most cases. A workman getting hurt and sueing would be a hard case to win. They have to prove you were at fault. The burden of proof is on the moving party. In the same vein proving they hurt your coach it is up to you to prove that in a lawsuit. If you leave instructions not to use your jacks and something is damaged that is a pretty powerful arguement. They were using your equipment without your permission and unless they have someone specifically trained on the leveling system they do not have an expert using it. That argument is applicable in both cases where you sue because of damage to your equipment or because they sue if someone got hurt. Same for tweaking a frame and breaking a window. You brought the coach in without a broken window it got broken in their care. If it happened because they used your jacks, their jacks. Temperature change in the garage whatever it happened in their care they are going to have to prove that it would have happened no matter what they did. That is a big burden to meet.


Safety was mentioned. Anyone that works under a vehicle without having it blocked up corrrectly is unsafe and I dont care what method they use to get it jacked up be it leveling system, hydraulic jack, air jack, air bag etc. all of these have the capability of losing pressure and dropping. I was jacking up a utility trailer that ways 600 pounds yesterday in order to get the tongue up so I could use the tongue jack, It was on a hill and kept sliding off the jack. Even though I was using a 20 ton jack to jack it up. There is no gaurantees.

If the tire place puts the jack under the axle. The only time I have had tired replaced the jacks were put under the frame and lifted that way. Your arguement about the increased raising if put under the axle is a good one but I do not know how many actual tire places do that.

I am always amazed at people who make the arguement damage to the suspension from just the weight of the tires and axles dragging it down if you jack up the frame. You do realize that when you level the suspension is stretched some no matter how high you have to level so the weight is put on the suspension then. In the case of my motor home that is basically all but a few road hours in the last 14 months because we have been living in it. But if we forget that fact and just look at what happens when it is raised where the entire weight of tires, brakes, axle etc are on the suspension because the tire is off of the ground. Do you really believe your suspension is that fragile. I could look up the formulas and do the math maybe someone with a degree in physics wants to do it but how much force is applied to your suspension when you are going down the highway at 60 miles an hour and hit a hole in the road. You have your 30 or 40 thousand pounds of mass traveling at 60 to 85 ( I do not believe it when i motor home passes my car doing about 85 but some do) that force is being applied to that suspension for an instant when the tire has dropped into the hole. I will admit not the entire force and it is for an instant only but there is a lot of force on the suspension from just driving down the road. Is anyone really going to argue that just the weight of the tire and axle etc is more than the force applied to the suspension from everyday driving. Look at the front suspension when you hit your a significant amount of weight is shifted to the front suspension from stopping.

I believe the ride control valves depend on the air compressor working which would mean the engine was running and that is usually not the case when you changing tires.

I am not saying it is a good idea to use leveling jacks for something they are not recommended for but most of the arguments against it are not logical and really do not follow the laws of physics.

[gemini5362]

Originally Posted by TQ60

Using a leveling jack lifts the frame that in turn causes suspension parts to lift wheel resulting an a lot of stresses on the suspension and frame while also requiring a lot of rise to get the wheel off the ground for clearance of tire due to the range of the suspension.

Lifting via correct jack is directly to the axle lifting the axle only a few inches to get the wheel off the ground and having normal stresses to rest of frame.

Huge difference!

Yes it can be done but not good.

I will refer the my response to shapeshifter on this statement. I do not believe that your suspension is that weak. The forces applied to it during everyday driving is a lot more stressful to it than just hanging the weight of the axle and wheel off of it.

Once again let me emphasize I do not think it is a good idea to do it. I would write on any work statement not to do it and I watch them work on my unit if the shop allows me to do so.

[TQ60]

The bottom line is we expect the tire folks to use the correct tools and procedures to do the task at hand.

If on the side of the freeway with a flat and leveler is rated to lift wheel off the ground then that certainly may be the safest option but a tire shop is expected to have proper lifting equipment along with proper training to safely and correctly lift said vehicle and mount the tires.

If any of them any where anytime at a shop asked I would question their ability as this speaks of being lazy or not properly equipped.

When we had tires installed it was in town where large rigs were the exception and cars normal.

They noticed the aluminum rims and apologies were given for delays as they had to locate and purchase a protector ring to avoid scratching the rim while removing the lugs.

Did not ask about leveler and used bottle jacks under axle.

This was a car focused dealer but did have proper equipment or acquired proper equipment to do the task.

Yes many lifting systems are capable of doing the task but we are paying the tire shop to perform a task and they are expected to do it correctly.

The suspension should not be weak so to speak but it is not usually airborne either.

[ShapeShifter]

Originally Posted by gemini5362

I can literally argue either side with no problem in most cases.

I'm sure that is the case. If the legal action were so clear cut that there is no possible way to argue for one side of the case, then there would be no basis for the action and it would probably have been settled long before arbitration.

If you leave instructions not to use your jacks and something is damaged that is a pretty powerful arguement. They were using your equipment without your permission

I agree with the rest of your legal interpretations (even though I am not a lawyer, I did take some introductory law courses in engineering school.) But I particularly agree with this statement: If you specifically told them not to use it, and they did use it and cause damage, it makes it MUCH more difficult for the shop to argue that they are not responsible. That was pretty much my whole point.

If the tire place puts the jack under the axle. The only time I have had tired replaced the jacks were put under the frame and lifted that way. Your arguement about the increased raising if put under the axle is a good one but I do not know how many actual tire places do that.

I also do not know how many tires shops use whatever method. My only experience so far with working on motorhome tires was on the side of the road. In that case, the technician did indeed place the jack under the axle, lifting only the wheel and not the whole frame. I will be in the market for new tires soon, so I will see how that shop handles the change.

You do realize that when you level the suspension is stretched some no matter how high you have to level so the weight is put on the suspension then.

Of course, the suspension is often extended somewhat while leveling (but not always: I usually dump air before leveling, and many times the chassis is lower than ride height once I'm done leveling.) But the point is that if leveled properly, you still have some weight on the wheels and the suspension is not fully extended to the stops.

Do you really believe your suspension is that fragile.

No. But my motorhome manufacturer apparently has some concerns since they recommend never lifting the wheels off the ground while leveling. They are quite adamant about it, having this block of text in large bold print and set off from the rest:

Originally Posted by Monaco Owner Manual

CAUTION
The leveling jacks are not designed
for changing tires. This can cause
problems with the suspension system,
frame alignment and damage to the
windshield(s). Never use the jacks
to elevate any wheel position off the
ground.

I don't feel the need to second guess the manufacturer. Are you sure you know the structure of the coach better than the manufacturer and are you willing to stand behind it if damage is caused by raising the wheels off the ground? I didn't think so.

I could look up the formulas and do the math maybe someone with a degree in physics wants to do it but how much force is applied to your suspension when you are going down the highway at 60 miles an hour and hit a hole in the road. You have your 30 or 40 thousand pounds of mass traveling at 60 to 85 ( I do not believe it when i motor home passes my car doing about 85 but some do) that force is being applied to that suspension for an instant when the tire has dropped into the hole. I will admit not the entire force and it is for an instant only but there is a lot of force on the suspension from just driving down the road. Is anyone really going to argue that just the weight of the tire and axle etc is more than the force applied to the suspension from everyday driving. Look at the front suspension when you hit your a significant amount of weight is shifted to the front suspension from stopping.

Again, you are talking about a different situation. In all of the cases you mention, the suspension is under various forms of compression. The suspension is designed to be in compression and supporting a lot of weight.

But when you raise the frame so high that the wheels come up off the ground, the suspension is no longer in compression, it is in tension. It is not designed to be in tension, as this is not a situation it routinely faces while driving unless you play Dukes of Hazzard in your motorhome and start taking jumps. When the suspension is in compression, the weight of the motorhome is being supported by the air bags that are also under compression. The air bags are very strong in that mode. But when you are dangling the tires, the air bags are no longer in compression, they are stretched to their limit in tension, as are the shock absorbers. If the full weight of the axle and tires (and any other unsprung weight like the large H frames on the front and back axles of my coach) are being supported only be the end stops of the shock absorbers, there is the possibility of damage to them - they do not normally reach the end stops in normal driving or leveling conditions. Same thing with stretched out air bags. While leveling, if the wheels are still in contact with the ground, then you haven't hit the extreme limit of these components so it doesn't matter if the suspension is partially extended, it's not the same thing as being fully extended.

From an engineering point of view, it's not hard to see how the durability of the suspension could be very different when in tension versus compression. There are many materials and systems where the strength varies widely depending on the type of load.

One classic example is a rope: it has very good strength when under tension (pulling on it.) That's what it's designed to do. But it has no strength under compression - try pushing something with a rope and it just bunches up.

Another classic example is concrete: it has tremendous compression strength, that's why it's used to support bridges, buildings, and many other structures. But it has very little strength when in tension - that's why they put steel reinforcing in it, to be able to handle the stretching forces.

I believe the ride control valves depend on the air compressor working which would mean the engine was running and that is usually not the case when you changing tires.

No. The ride height control valves depend on there being air in the air storage tanks. There is usually plenty of pressure in the tanks to allow several up/down control cycles of the air bags before the pressure gets low enough that it needs to be topped of by the engine's compressor.

But it doesn't really matter: if there is no air available for the ride height control valves, then raising the axle will not cause the air bags to inflate, so they will not cause the frame to rise. This would actually improve the situation. Your argument actually reinforces my point.

I am not saying it is a good idea to use leveling jacks for something they are not recommended for but most of the arguments against it are not logical and really do not follow the laws of physics.

But many of them are logical and follow engineering principles, if you study them and look below the surface. For example, many of your "no difference" arguments are definitely different when you look at the details. But I agree that some of them may not make sense from an engineering or physics point of view, these are the ones that are probably being made by the lawyers!

For example, my coach's manual specifically warns about raising the wheels off of the ground with the jacks. Is that because the engineers have decided that there is a weakness that has the potential for damage? (I can see how this could possibly be the case, like the travel stops of the shock absorbers not being able to support the unsprung weight of the axle.) Or is it because the corporate liability lawyers insisted it be there in case someone experiences injury or damage while doing so, and they want to be able to say that they told the person not do that? (Much like your example above that if you tell the shop not to do it, and they do it, it will be much more difficult for the shop to pass the blame.)

Either way you look at it (engineering or legal basis) it doesn't really matter: the recommendation is to not do it, and there is no real need to do it, so why do it?

[okie143]

Are there any freightliner, spartan, etc., chassis people on this forum that have their ideas? Has anyone sent this post to the chassis people for their 2 cents worth?
Don't really need their opinion but I would like to know what they think, even if their owners manual says something else.

[gemini5362]

Shapeshifter

I love to argue with engineers I usually use phrases like cannot see the forest for the trees. They are so focuses on one problem they often lose track of the real life situation. In my non professional opinion the stresses put on the suspension driving down the road far exceed the stress put on the suspension when holding up the weight of one tire, brake assembly and part of the differential if only doing one corner. If doing both sides then the weight of the entire suspension is still minimus in comparison to the stresses from driving.

I believe your statement is probably correct about it being a legal reason for putting those warnings in there. Once again you get into the having to prove it was not your fault when things get broken. If the equipment is used in a manner that is in violation of the manual then you do not have to prove whether or not your equipment caused the problem you can demer to the evidence. ( even if our equipment caused the problem it was used in a manner in violation of our warning not to do that) That language is pretty much a guaranteed legal covering of your hiney whether there is an engineering problem or not.


I have said this repeatedly that I do not think it is a good idea to use the leveling jacks to change tires I just do not think it is the end of the world if someone does and Like the legal language for the companies. If you write on your service order not to use the leveling jacks for this purpose if something does not happen you are a long ways down the road towards winning any legal issues.

[ShapeShifter]

Originally Posted by gemini5362

I love to argue with engineers I usually use phrases like cannot see the forest for the trees. They are so focuses on one problem they often lose track of the real life situation.

I often think the same thing about lawyers.

In my non professional opinion the stresses put on the suspension driving down the road far exceed the stress put on the suspension when holding up the weight of one tire, brake assembly and part of the differential if only doing one corner. If doing both sides then the weight of the entire suspension is still minimus in comparison to the stresses from driving.

We can agree to disagree. You can't see a difference between the two situations, and I can see where stretching it to the limit introduces different forces than driving, forces that while they may be small compared to the driving forces, the suspension is not necessarily designed to endure them.

Now, as for the rest of your post, I think we can agree to completely agree. :thumbsup:

[Mr_D]

When we had our '02 DSDP I found:
Newmar said it was OK to lift the whole rig with the jacks
Spartan said it was OK
Reyco Granning said it was OK
Koni said it was OK
HWH said it was OK (4 12,000# rams and rig weighed 32,000#'s)
So I took it as being OK! Although you did need to chock well!

[Dtwallace]

Is it not normal procedure to use your leveling system to stabilize your suspension system at the tire shop before the coach is jacked up to perform tire service?

I think it is at times since the air springs may leak down due to an uneven lift when the tire repairman is working.

Then once the coach is lower, and the wheel is higher into the wheel well, it has less clearance and harder to remove.

I would never let the tire tech operate any system on my coach, that's just asking for trouble.

It seems like we are putting too many variables in this that don't pertain to the point.

[Dtwallace]

Mr. (D),
How in the world did you chock those wheels while they were in the air???????��

In reference to the argument about over extending the suspension system.
Obviously we have never seen real axle or suspension work being performed.
A leading link suspension system is made to be moved from stop to stop. But let's not confuse that statement as to say this is in normal operation, but it could if circumstances dictated, and not sustain damage.
Now, in normal maintainance of the suspension system, and when hanging the axles, all of the normal components for operation should be (should be) connected.
That's means, don't hang the axle from the bags without the shocks attached.
The shocks should be extended occasionally for inspection for leaks or internal failure that will manifest it's self as a binding or sticking shock, valve failure that will let the shock rebound without restriction, (dead shock as some have called it).
Are we ever going to inspect a shock this well, I doutb it.
Your suspension system is more robust than you can imagine. It's made this strong for your safety and years of reliability.

We could go on and on about lifting your coach with the leveling jacks and in the end, safety is the first concern. Some of us including myself can lift the whole coach, or as the manufacture suggest, (one end at a time). I ephesise one end at a time because some have balked at lifting a corner.
Guess what, that's correct, one corner at a time is warned against by all the manufactures and is just common sinse.
But sometime we can't muster up that common sinse so that's why we have the government do it for us. Ok, sorry, getting off track here.
Every time someone insists that you should not raise the rear coach wheels off the ground because of the side loads, I'm waiting for someone to mention side loads don't exsist if level. But then, we are right and wrong again, because side loads do exsist until the coach is level. But then why are we trying to level in such an extreme incline anyway?
Ok, I'm ready, I'll be damned to hell for this post I know.
But just my cts

[ShapeShifter]

Originally Posted by Mr_D

When we had our '02 DSDP I found: ... So I took it as being OK! Although you did need to chock well!

Go for it! So it seems that there is quite some variability in the manufacturer's recommendations.

Originally Posted by Dtwallace

Is it not normal procedure to use your leveling system to stabilize your suspension system at the tire shop before the coach is jacked up to perform tire service?

I've never seen this done, nor recommended, but I suppose some do it that way.

My experience is that it takes a while for the air springs to leak down. Even raising and lowering axles, which causes the ride height valves to purge air then refill with air, I would think that there should be enough air in the tank to allow enough cycles to get the tires changed.

I would never let the tire tech operate any system on my coach, that's just asking for trouble.

I agree, and I think you have the right to tell the shop not to use the systems.

It seems like we are putting too many variables in this that don't pertain to the point.

Agreed. Too much discussion on why you should or shouldn't change tires using the leveling jacks, when the real discussion is that if you don't want it done that way, the shop shouldn't do it.

The point is that if you don't want your jacks to be used to change tires, for whatever reason, you should have the right to say so and expect it to be honored. There is no reason a properly equipped shop should need to use your jacks - if they do, then they are probably not a properly equipped shop and perhaps should not be working on your coach?

But if you want to let the shop use your jacks, then go for it: let them do it. But don't question the motives of those who don't want to do it. Do their reasons for it really matter? It's their coach, and their decision. Trying to talk them into letting the shop use the jacks, or questioning their motives, is not the point of this discussion.

I know I'm guilty of drawing out the discussion and I apologize for it. I guess I spent too much time trying to justify why people should be able to have their choice, and why it might not be the best idea.

Originally Posted by Dtwallace

Guess what, that's correct, one corner at a time is warned against by all the manufactures and is just common sinse.

But common sense is so uncommon these days. Are you sure the technician has that common sense? Does the technician know about the manufacturer's warnings? Are you going to train the technician (and any others in the shop who may take over the job or help)? Or is it simpler to just tell them not to use the system and avoid the whole issue?

Every time someone insists that you should not raise the rear coach wheels off the ground because of the side loads, I'm waiting for someone to mention side loads don't exsist if level. But then, we are right and wrong again, because side loads do exsist until the coach is level.

Agreed. And the side loads still exist between the ground and the end of the jack if the ground is not level, even though the coach is level. But you're right, that's a whole 'nother discussion.

__________________

Getting back to the original discussion: if you don't want the shop to use the jacks, just tell them so. If you're afraid that the order taker won't tell the technician, put a note on the jack controls. If you're afraid that won't be enough, you could always pull a fuse, or disconnect plugs from the control panel, the control box, or the power mechanism, whichever is easier to reach - but instead of doing that, you should probably be looking for a different shop that will do what you want