Originally Posted by M109Rrider
........Does it make sense to say that the more this style jack is lowered the stronger it would be?
I was talking with my son about that last weekend. We both felt the same, they would be stronger. When lowered on the concrete blocks in the pic you posted, the thin support arm seems to take on most of the weight.
I think a block of wood is okay since it will give a larger footprint for the jacks which will help to keep them from sinking into the ground. Of course if your on a concrete or asphalt pad you wouldn't need the wood blocks.
As far as fore and aft movement, my X-chocks take care of that.