Happijac lubrication

bb_94401 wrote:
There is something I don't quite get about the clinch spring. Can someone help me out with my thinking?

It seems to function in one direction to tighten down on the cyclinder that mates against the square thrust plate? The added friction of the cyclinder against the plate then adds resistance to prevent the worm gear from freewheeling under the weight of the camper and slowly lowering the jack? So in this case it would seem that friction is good and little lubricant would be a good thing and that is why there is no needle bearing there.

When turning the gear to raise the camper, the spring would unwind and the cyclinder would not rotate. However when turning the gear to lower the camper the spring would lock tightly and spin the cyclinder against the square thrust plate. With no or little lubrication, gauling of the parts would occur in this direction.

So if you lubricate it really well, it may freewheel? If you don't, it gauls and won't rotate in one direction. Then when the roller needle bearing fails it gauls in both direction without lubricant. Do I have this right?

To put this is perspective, has freewheeling been a problem for people who have rebuilt their jacks and heavily greased the mating faces of the square thrust plate and the cyclinder?

It would seem that with electric motor driven jacks, there is added resistance to freewheeling vs. the manual jacks.

Seems I've read more gauling, noisy, locked up jacks vs. freewheeling jacks and collapsed campers. Does this reflect the relative value / risk cost of jacks vs. cost of camper.

You have it 100% correct. The cylinder and and square plate form a brake which operates in only the "lowering" direction because of the 1-way spring clutch. In the raising direction the needle bearing turns. Like any brakes some wear is normal. The worse wear is lowering the camper with the camper's weight on it. Once the jacks leave the ground (when loading up), the slack in the assembly pretty much unloads the brake anyway. So the more you lower your camper all the way down the more wear your jacks will probably see.

I'd rather service a noisy one than "improve" the design and make the brake fail. With a motor connected it really can't backspin but I have and love the quick release option and will gladly put up with the brake system to keep it. HJ may be covering their butts in case someone pulls a motor without supporting the camper on models without the release lever.

I don't know if there's much to improve unless there's a small round clutch friction disc you could drop in there?