Flat

JRscooby wrote:

Kayteg1 wrote:
10 tons?
I wonder what it takes to bend the axle?

What does it matter? The jack can't put any more force than what the axle weighs, no matter the capacity. But lifting 12,000 lbs with a 6 ton jack is more of a workout than with a 10 ton jack.
Don't think it matters much on little stuff but I once bought a truck that had about a 2 inch round hole in the bottom of the axle housing. Pulled the Diff, found the piece. Somebody had put a jack under the flat part of that 20,000 lb rated axle.

On my tool truck I carried a 2 foot long piece of truck frame too put under my jack if needed. Overkill for RV, but if I needed to lift the end of axle that might have 30,000 on it while setting on dirt I had a place to start.

Somebody mentioned the miles you haul a jack, and don't use it. Best if you keep the jack upright, even when not in use.

10 ton jacks usually also tend to have a larger contact patch on the axle tube than the smaller 6 ton jacks do. Ergo why I mentioned the high heels effect, where weight concentrated into a very narrow contact patch can create excessive PSI on that point and in the case of an axle, possible cause a deformation in the form of a flat spot in the tube or concavitation.

In this case, the difference is between putting a chunk of 12,000lbs on the contact patch the size of a quarter vs an old school silver dollar.