Fishbreath wrote:


If you feel that comments to your questions are not accurately answered, I would suggest contacting the manufacture for answers.
Good luck and welcome to the Forum

JoeChiOhki wrote:

The logic I can see and its not just unique to Happijacks is the rear jacks in most cases have the tubes anchored the full length down the wall of the camper, allowing the camper to restrain the side to side movement of the jack tube. The fronts are only anchored on at a very small section of the tube turning them into giant fulcrums.

When you tip the nose higher the rear jacks are restrained by the camper itself and don't begin to flex to the side as the weight application changes.

When you go the opposite direction, the front legs have nothing to prevent them from flexing or twisting toward the rear, apply enough downward dog pressure and the jacks will either buckle or the anchor points will fail, because you've been applying a twisting forcing to that limited anchor area with a fulcrum. (Think of how using a cheater bar on a socket wrench amplifies the force at the nut or bolt, you're doing the same with your front jacks).

HMS Beagle wrote:

I think the reason they say this is due to the potential for forward weight shift if carried to extreme. At normal angles, not a problem*. I don't think it is due to worries about bending the jacks, certainly carried to extreme you could bend the jacks, but you are nearly equally likely to bend them tilting aft as forward - the bending moment on the jacks is nearly the same - and they do not caution against tilting aft. It cannot be due to concerns about tipping over forward, it would be a highly unusual camper that would do that even at full jack travel.



* Take a 4000 lbs camper, vertical CG 4' above the box floor, 10' between jacks and longitudinal CG 3' back from box front. Level, front jacks take 2800 lbs. 5 degrees forward slope changes this to 3080 lbs. If the jacks are that close to failing you have many more issues to address. Yes, I am an engineer...

mt-ed wrote:

Well folks, as promised here is the official word from happijac....

If you raise the back of the camper higher than the front, you are displacing gravity on the camper. You are making the front end forward heaver which can cause the camper to fall forward.

I cut and pasted their response verbatim from their email.

Thanks for all the interest, input, advice, and conjecture everyone!!

mkirsch wrote:



Um, okay? "Displacing gravity?"

In other words the person who answered your question had no clue. What they said is absolute nonsense. They just want you to go away.