Happijac lubrication

MTBob wrote:

To confirm, your 4100 model had a six ball clutch? If so, you've now got me wondering if there is a difference in the 4100 model, depending on the year it was made.

Regarding the clutch nut torque: 30 - 35 inch-pounds is quite a bit different than what I used (9-10 inch-pounds). This seems odd since I would think that a six ball clutch would have more resistance than the 3 ball design that I have. In any case, I would rather error on the side of having the clutch set too loose than too tight. If the clutch is over tightened there is a risk of stripping gears or overloading the motor - (I'd guess that's what would happen).

It would sure be nice if HJ company provided some guidance as to parts lists, and full maintenance of these jacks.

No, the motor clutch I took apart is on a 4500 - not a 4100. I bet they use the same motor though, because HJ only sells one replacement motor. My camper is 2002 vintage I believe and these are the original jacks. I suspect there was a design change somewhere along the line, so if yours are newer, maybe they evolved from 6 to 3 balls or vice versa. Or maybe it's an issue of multiple suppliers. Also, the balls in my clutch look to be a LOT smaller than yours, so shallower depressions. Not sure how that would affect the torque settings.

I'm wondering if it would be OK to try overloading each motor individually to test the clutch in each one. If the motor stalls, then the clutch torque settings need to be backed off. I've never heard any of mine click before I had this frozen jack, but then I'm pretty careful about not retracting them so hard that the motor stalls or the clutch clicks. I usually stop them individually when I think they are all the way up and if I guess wrong and hear the motor bog, I stop immediately and back it off a bit.

I'm also questioning the accuracy of setting them by the torque on the nut. It's a lock nut, so the torque will be greatly affected by the drag of the plastic locking material, not just how tight the nut is against the spring plate. The drag of the plastic would be pretty specific to who made the nut, or even across lots, I would guess. Not sure what kind of SAE standards there are for lock nuts, and how tightly controlled they can be. It would seem that a nut that has been re-used would probably have less drag than a brand new one. A better solution for repeatable torque settings would be to torque a plain nut and then use a jamb nut to secure it.

I'm going to try one last ditch effort at saving my jack by trying to get a replacement thrust bearing at my local bearing supply house tomorrow. If I can't get a replacement, I'll try swapping a bearing from a good jack to the problem jack and see if the problem goes away.

-jj