Happijacs, what will happen if.........
When reading about the operation of my happijac electric camper jacks, it stated numerous places, "Never raise the back of the camper higher than the front". Why? Is the location of the front jacks...
Forum Discussion
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...
I do also wonder if it has to do with Happijac's choice to use square tube jacks, as their jacks have been known to buckle at the pressure point between the outer and inner tubes before. Round tubing is naturally stronger by shape than square tubing and will take a good deal more strain without failing catastrophically than square tubing does.
