Why Do Landing Gear Jacks have Bracket that Goes Above One Weld Stop and Below the Other

Question:

I found your dimensional drawing for these jacks to be confusing. It shows the dimensions between the top of the upper weld stop and the bottoms of the lower two stops and the dimension between the top of the middle stop and bottom of the lowest stop. Since Ultra-Fab recommends installing their jacks with both weld stops BELOW the clamping brackets, wouldn’t it make more sense to show the dimension between the tops of the three stops? Indeed the drawing Ultra-Fab has available for download on their website is far superior to that on your website. Why not just use theirs? Why Bulldog and Lippert recommend placing the upper stop BELOW the upper bracket clamp and the lower stop ABOVE the lower clamp is beyond me. All the force on the jacks as they are supporting the weight of the trailer are going to be in the upward direction relative to the trailer frame. It therefore only makes sense to mount the jacks with the weld stops BELOW the clamping brackets. The only time I can think of that you would ever have a downward force on the jacks is if the fifth wheel is hitched to the truck and you are trying to retract the jacks out of mud they had sunk into. This should not happen since you should use blocks below the jacks in muddy conditions to help spread the weight out. But even if it does happen, these forces are far less than the upward forces of supporting the trailer’s weight, and they’re easily compensated for by the clamping grip of the brackets on the outer tube as long as the clamping carriage bolts are properly torqued.

asked by: David B

Expert Reply:

If you have both weld stops on the same side of the brackets on the RV they wouldn't be able to jack up the trailer and then also not fall once they've retracted. There is quite a bit of force on the jack when they are lifting a trailer up, but if you think about the jacks when they are retracted on a trailer what would hold them in the air if there wasn't a bracket keeping the jacks from sliding down.

expert reply by: Jameson C