[DK on the road]

Jack, I'm in the market for air over hydraulic jack and stands, at the strength your talking about. Do you have a brand, model or any help that I can start searching for. I'm thinking a plate of 3/8" 2' x 3' for the jack and at least 2' x 2' for each stand.

Feedback appreciated.

[Jackflash]

The jack and stands that I have are both OTC branded purchased off Amazon.  The stands are 22 ton and the jack is 20 ton air assist.  They have worked very well so far.  I have only used them in a paved area so far The size plate you might need will of course depend on the bearing capacity of the soil you are dealing with, the stands have a fairly large base plate, probably close to a sq ft.  Seems like the base on the jack is a bit smaller.  The plates you are considering will probably be more than sufficient in all but the very softest of soils.

https://www.amazon.com/dp/B001C6OZ7U/ref=cm_sw_em_r_mt_dp_U_cANKCbH6T9QHD
https://www.amazon.com/dp/B007KIMALC/ref=cm_sw_em_r_mt_dp_U_YFNKCbBZAQ4EE

[Jackflash]

By the way, 3/8" plate weights 15.3 lbs per sq ft so the plates will weight approx. 92 and 61 pounds each for the 6 and 4 sq ft plates.  That might be tough to position while laying down reaching under the coach.

[Richard]

Weld a couple of loops on the plates, and make a rod with a hook so you can pull from either side

[pairodice]

Yes Richard, I was thinking the same for the stands - they are heavy once they are under the coach... I might try a 1/2” or thicker plastic cutting board - we used those under the our WanderLodges hydraulic leveling jacks (had about a 1 foot square pad on them) and they worked great, tied a rope to them to position and pull them out.

---

So what’s the best way to ‘TEST’ the ground you are smashing? I’m pretty sure jumping up/down on the steel plate won’t do much (other than amuse your spouse/SO)...

[Jackflash]

Soils engineering is a science to itself and requires a significant amount of expensive equipment.  The only way I can think of to get a general idea of the bearing strength of a site would be to take a steel rod an inch or so in diameter and long enough to make it weigh 25 lbs or so, weld a small round plate on the end that had an area of about 5 or 6 square inches and drop it from a set height (12 to 18 inches, always the same though) and measure the depth of the indention.  Log the results at every site you visit along with the reaction of the soil to the coach wheel load and after a while you will have a data base that will allow you to pre-test a site before driving out onto it avoiding getting stuck or sinking your jack stands.  Might be handy for all the boondockers.

PS: The bearing area of a coach with a tag axle is only about 2.5 square feet on each side at the rear so if your coach isn't sinking then a jack stand sitting on an 18 to 20 inch square plate shouldn't sink.

[pairodice]

Thanks Jack! I may do that since I am in a lot of ‘iffy’ spaces that I would like to be able to work on the coach. I know I pushed some nice holes in the ground/pavement with our Wanderlodge’s leveling jacks...
Richard: It just dawned on me that I already have a long aluminum rod with a hook on it for the awnings :-)

[DK on the road]

As for soil strength, The drop hammer approach is excellent. If your able to test virgin soil, in other words, not scattered with loose soil, rocks etc, You can use a pocket penotrometer. $55 to $85. simple and very self explanatory to use. Just press the pointed end into the dirt, as it penetrates, a teflon ring will slide to a number representing a tons per square foot.

Somebody correct my math if I'm wrong please but if your rig sits on 2.5 sq ft on each side and I'm about 40,300 across the whole back end, then I need, at a minimum, 40,300 / 2,000 = 20 tn / 5sf = 4 t/sf minimum

You may want the foot adapter to check softer soils like sand. PS, I've been stuck in sand (Pismo Beach) with a prior coach. Never again

[pairodice]

Since I never bought the jack or stands but have them both on the way now: will some 4x4 pressure treated pine work for cribbing for the front wheels and then use the new 22ton jack stands for the rear wheels?
Also I am on a semi-paved dirt site - should I use some of the cribbing under the jack stands (may be too high to get under the coach)?
Any idea where I could find a 3/8” (or 1/2”) steel plate (would Aluminum work?)?

[pairodice]

On some advice of a friend I am going today to get (5) 2foot x 2foot x 3/8” steel plate sections from Metal Market here in Maryland/DC area. I will use one plate under each stand and then one for the 20ton air/hydraulic jack I bought from HF yesterday. Two 22ton jack stands are on their way from Amazon. I will also be getting some 4x4 treated pine lumber to cut down to 2foot sections to build cribbing out of. I’ll probably leave it here at the park if/when I ever leave... I don’t want to carry all that extra weight when i can get it easily at Homey Depot...
Anthing I’m missing or am I doing something incorrectly?