Jacking

[rotaxman]

Does anyone have a suggetion on what the proper way to jack the MS is. I have Trailair center point and have the curbside rear tire going down.

I want to make sure that I don't twist something that shouldn't be twisted. Or put to much pressure on a small lifting area.

Thanks

As always good camping

Joyce and Jerry

[bstark]

Jerry: I'll hazard a response based on my experience so far. I put the jack under the center of the plate that fastens the spring pack to the axle, center the depression in the head of the jack over the "tit" from the spring pack that locates it in the plate and slightly protrudes through the bottom of the plate so that you are lifting the axle at the same point that normal suspension forces would be acting on the system. And lift the axle just enough to remove the wheel. All things being equal you are putting no more stress on the Trailair than it would be subjected to if you were to run over a small speed bump.

[rverdlm]

I think Bruce has it right.

[Motor31]

In speaking to the Dexter rep that was checking the status of my bearings he indicated the jack should be placed under the frame of the trailer and never under the axle including the spring attach point. The Dexter owners manual has repeated cautions not to support or jack under the axle, suspension or attach points. There is no explanation in the manual just statements to never do it.

[bstark]

Mike: Yep, I encountered that same cautionary note in their literature. I went through all of this years ago with them and it boils down to; they don't want you to possibly bend one of their axles by jacking the off-camber wheel into the air while the other wheel is bound or trapped in the opposite camber by road surface and other axle being at opposite tilt.

You may even encounter an episode where an emergency tire repair vehicle operator refuses to lift the entire trailer just to change a tire as being "in his mind" unnecessary, too difficult, and even unsafe.

This of course wouldn't be a problem if they (Dexter) would simply make their axles out of thicker wall tubing to begin with.

Jacking the frame of the(Trailair equipped) trailer requires lifting the entire side of the trailer a terrible distance into the air to compensate for it's tendancy to rotate shackle assembly towards the flat tire. You actually have to lift that side enough for the entire weight of the trailer to come off both wheels/tires as well. This distance is slightly exacerbated (having to jack even further as you take the weight off one side) by air transferring over to the light side on systems that still have the single fill port. I feel better about jacking under the axle at the point where all of the service people currently do it.

The key is making sure (if possible) you're on flat surface with your axles out of any bind situation such as one side of trailer in a pot-hole or ditch and not to be too aggressive in how far you lift the offending wheel.

[rverdlm]

I still agree with Bruce, especially about how high you must jack when under the frame. In my mind it becomes a safety issue. Also under the spring plate you're only lifting the weight on that tire, where as under the frame you must lift the entire weight of that side of the trailer. I've been jacking under the spring for years and I've never bent an axle. Just be careful to center the jack under the spring plate.

[wingnut60]

l agree the best way to jack up the trailer is in the spring pad plate. While Dexter may say no to this, I believe their concern is if we were to place the jack on the axle HOUSING/TUBE, there would be damage to the axle. No way am I going to jack on the frame to get the entire side of the trailer high enough to get the tires off the ground.
Why not use one of the many ramps that are designed/sold to pull one tire up on, thereby getting the other tire off the ground?

[bstark]

Wingnut60:
Those devices work very well with conventional suspension with the rocker beam center piece (for every inch one spring shackle rises the other end of the dogbone goes down 1") but with the Trailair bladder there is quite a bit more "roll" to the center beam (the whole bladder device rotates but the bladder also expands as weight comes off so you get a magnification of the shackle movement) and you would have to have the good tire up on some sizable ramp to eventually lift the flat one off the ground.

[rotaxman]

Wingnut 60
Bruce

I would also not want to put the entire weigh of one side of the trailer on just one tire I'm sure beyond a doubt that would put that tire way over it's max carrying cap

Thanks for all the replies I'll jack on the spring pad.

As always good camping

Joyce and Jerry

[wingnut60]

Rotaxman--
thats an interesting thought--hadn't considered that. DUH! Tires on mine are already at max weight. Guess thats why I have the 10ton bottle jack.

[Motor31]

If you get a flat tire, the weight of one side will already be on one tire..... :P

[rotaxman]

Mike

I guess I should of been more specific in my case I have a tire that is slowly going down and do not want to put the entire weight on the good tire while have the leak fixed.

You are correct though once the tire goes flat on the road you have already overloaded the good tire. Good point.

As always good campng

Joyce and Jerry

[47hook]

Actually, with the flats that I've had, the rim is sitting on the flattened tire which is still in contact with the ground which is then still supporting weight. The concern I would have is that if the tire pressure goes below that which is needed to support the weight that the tire is supporting, you have overloaded that tire. At Goodyear's website, it states that a tire that has lost 20% of it's pressure (IIRC) is considered flat and should be inspected for damage, not just what caused it to go flat. Plus, it can't be good for a tire to be squashed flat if completely or almost completely out of air.

So, if you have a slow leaker, try not to let it go below the pressure needed to support the weight.

So far as jacking, I agree with those that say use the spring perch as a jacking point, provided you don't raise the axle past the point it would be with a fully inflated tire. Don't think that would put any different stress than being supported by a tire.

[billr]

I have to agree that jacking at the spring plate to remove one wheel should be fine, and no added stress is sent to the other tire since the wt is supported by the jack.

I do disagree with the other tire being ok after a flat or blowout that had been driven on at all. Once the load is carried by the single tire it has been overloaded whether the carcass of the flat is there or not. If you leave the other tire in place, you will only be buying time till it possible blows starting a vicious cycle. Have seen and heard of many that this has happened to.

If the tire goes flat with no coach movement, the other tire should be ok provided it hasn't sat for very long. The flat tire will need to be inspected for sidewall damage from going flat. A decision needs to be made to fix or scrap. This is assuming it hasn't been driven on below normal pressures.

These are IMHO, and what I go by.

Cheers,
Bill