Surprising Danger experienced With My HappiJacks

[covered_wagon]

The circuit board went bad on my Happijacks so I had to switch to manual use using the crank. This essentially disengages the electric motor from the gears allowing manual use of the hand crank to the gears for raising and lowering. The surprise came when removing the crank(jack switched in the manual position) when I removed the crank the jack would spin on the weight of the camper and would have gone all the way down and left me crushed under the camper had I not immediately put the crank back in quickly and switched back to the electric mode.

It was very dangerous, both front jacks acting the same, would have also crushed my wife's newer car with me in between.

Just a thought to warn you folks that have nicely lubed your jacks as I have. It would be wrong of me not to inform others about this.

[covered_wagon]

Hoping they notice this thread... otherwise I have to wait till I have more time to call them. Working 8-9 hrs and commuting 3 hrs round trip takes a toll on a person.

[mkirsch]

What does Happijac have to say?

[covered_wagon]

Thanks for the interest and thoughts on this. The more aware the better for safety anyway.

The pinion gear on the electric motor, being so small, does lock the jacks position.

There has to be some sort of additional brake to prevent free spin when motor is disengaged. Suppose your little daughter fell down and got hurt the way children seem to do, which distracted you after you pulled the lever in the manual down position. You would not want to return to a rolled camper from a spun jack. There has to be some sort of safety stop.

Another great thought....finding your jacks are worn by way of ruining your camper isn't a good thing. Must be a better way, at least warning owners in the manual. Either that or I lubed where it is not supposed to be lubed, which should also be in the manual. Still, IT seems implausible somehow being that it is A mechanical device.

[wnjj]

AnEv942 wrote:
Thanks Billtex-manual isnt with the pdfs located in the TCU.

So the lever in free position will allow jack to travel on its own. Either down or pushed up by load.

I assume then nothing wrong with the jacks, you switched to free, removed the handle and did as design allows.

I read, either manual jack or elec., switch lever to free and it is. Yous, due to lube, maybe more easily able to 'free' wheel, but not the cause. Actually seems what 'should' happen.

Incorrect. The (normally operating) jacks cannot be retracted without the crank or motor. That's the whole point of the one-way brake system. The manual mentions locking to prevent the jacks from extending.

Also, only the 4600 model jacks can be lowered manually with the lever disengaged. The 4150 and 4500 need to be cranked or powered. The 4150 is acme thread which cannot be backspun and the 4500, though ball screw like the 4600, does not have a roller bearing under the horizontal gear so the friction between the gear and square plate acts like a brake when you try to push down and free-spool the jack.

[Joe417]

That is something I had missed in reading the instructions. Fortunately, I haven't had an issue. I have one jack that is currently in the un-locked position but the camper is sitting on supports.

I had manual Atwoods on my previous TC. All you had to do was push the lock in and they would run down under their own weight and faster if you put a foot on the jack pad.

I have tried to "unlock" my 4500 jacks from the motor and stand on the jack pad to quickly run them to the ground. They would not rotate down under "human" pressure, I had to use the motor or the crank handle.

I would not have thought the spring and motor coupling, without the motor installed, would have kept the jack from moving. But that's what they seem to be saying and showing in the picture on the instruction.

I'd be interested in hearing what Happijac says about it.

I also wonder if the friction of the Acme screw vs the ball screw design plays a part here.

[AnEv942]

Thanks Billtex-manual isnt with the pdfs located in the TCU.

So the lever in free position will allow jack to travel on its own. Either down or pushed up by load.

I assume then nothing wrong with the jacks, you switched to free, removed the handle and did as design allows.

I read, either manual jack or elec., switch lever to free and it is. Yous, due to lube, maybe more easily able to 'free' wheel, but not the cause. Actually seems what 'should' happen.

[billtex]

The HJ manual does say to be sure to "release lock when cranking/re-set lock when not cranking".
OP did not say if he followed this procedure...

Clickety

[wnjj]

Joe417 wrote:
If you put oil in the oil holes that are in the crank handle opening as advised by Happijac, some of it end up inside just as pouring it down the gears with the electric motor removed.

Extra oil shouldn't cause an issue like this. The old Johnson and Evinrude electric transmission used this type of design but submerged it in oil and it worked great.

I could see where something under the spring could be a problem or the shaft surface under the friction spring could get worn or the spring get broken could possibly be a factor.

Speculation...................

Happijac recommends "a few drops of light oil" which is different than "pouring a little 30W". I don't know enough about the cinch spring one-way design and you may be right. It may well work fine submerged in oil. Clearly, though, something is wrong with the OP's jacks and it seems unlikely that 2 of them have broken springs (though not impossible).

If they were mine, I'd have them apart to see what's going on there.

[RamTC]

One of my rear Happijacs began to collapse in on itself under load, luckily it was on the rear as it would have rolled my Arctic Fox. I could hear the threaded rod slipping past the top nut, very scary. I contacted HJ and there response was basically that their jacks are only designed for a 6 year lifespan.

[Joe417]

If you put oil in the oil holes that are in the crank handle opening as advised by Happijac, some of it end up inside just as pouring it down the gears with the electric motor removed.

Extra oil shouldn't cause an issue like this. The old Johnson and Evinrude electric transmission used this type of design but submerged it in oil and it worked great.

I could see where something under the spring could be a problem or the shaft surface under the friction spring could get worn or the spring get broken could possibly be a factor.

Speculation...................

[Kayteg1]

wnjj wrote:

covered wagon wrote:
Poured a little 30 wt. oil down the tubes below the gears.

I wonder if that got where it wasn't supposed to? I'd think that would run right over the cinch spring assembly. I'd call Happijac and ask them what they say about that method of lube. As you can see, you really don't want to mess up the intended function of the brakes.

x2

[wnjj]

covered wagon wrote:
Poured a little 30 wt. oil down the tubes below the gears.

I wonder if that got where it wasn't supposed to? I'd think that would run right over the cinch spring assembly. I'd call Happijac and ask them what they say about that method of lube. As you can see, you really don't want to mess up the intended function of the brakes.

[covered_wagon]

No except I took the gear heads off and lubed the gears. Poured a little 30 wt. oil down the tubes below the gears. I also lube the lowest bearing inside the electric motor by removing the plastic covers once a year. There is a small weep hole in the motor housing after you remove the cover that allows a shot of oil to hit that bearing.

[wnjj]

There is a cinch spring/barrel setup that acts as a one-way brake. It clinches when the jack is collapsing (either under the weight of the camper or with the crank/motor). Once cinched, the barrel inside the spring now has friction to the square plate which becomes a brake. The more load (i.e. camper weight), the more braking there is.

For this to work, there cannot be too much lube between the barrel and square plate or under the spring itself. Obviously the springs must be intact too.

Have you ever taken your jacks apart to lube them?

Refer to KKELLER14K's awesome post for pictures: http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/22881036.cfm