Happijac motor drive

[racedrvr]

I have a Bigfoot with Happijacs. One of them keeps blowing the fuse. The jack moves freely when manually cranking the jack. Do any of you know if all the jacks use the same drive motor assembly? I have 4500 series jacks on mine, and I am looking to replace the bad one. I don't know for sure what the part number would be. I have found 600510. Will that work?

[Harleybullet]

I had a problem with the 2 drivers side jacks and it was the fuse... the front one works now but the rear must be a motor problem.... I use a socket and drill with no weight on the jack and the a breaker bar for the next few inches.... I guess the old ways always come back hehehe

[Moose10]

DWeikert wrote:

racedrvr wrote:
Hi Dan, I had used the jack two times just a couple weeks before it "stuck" so I thought it couldn't be "seized". I just didn't think it had had enough time for that. I put a rag on the motor output shaft gear and grabbed it with a small pliers. It didn't take much force for it to loosen up. I then hooked up a 12 volt power supply to the motor and ran it a few minutes in each direction. It ran fairly smooth from the beginning and seemed OK. I put everything back together and ran the jack up and down enough to put normal loads on it and again, it ran fine without any unusual noise or vibration. There had to be some moisture down in the motor bottom bearing to cause it to "stick" so I suspect it's just a matter of time. But for now it looks like I am OK.

Thanks for clarifying. A good nudge could've been anything from the pliers you used to a pipe wrench and a breaker bar. 🙂 I'll give the pliers a try next time I have problems, and I'm just a little annoyed with myself that I didn't give something like that a try before sending mine back.

From my experience, it's not the bearings seizing up its actually the rotor coils rusting/corroding to the stator magnets.
When I took mine apart that had blown the fuse, I cleaned it all up with a scotch brite pad and then siliconed the whole plastic housing up. I also keep plastic bags over them when parked for extended periods.

[stevenal]

racedrvr wrote:
There had to be some moisture down in the motor bottom bearing to cause it to "stick" so I suspect it's just a matter of time. But for now it looks like I am OK.

That's what happens. Disassembly and bearing replacement is not too difficult. Warm the plastic cover a bit, and use an air nozzle at the drain hole to remove (learned that trick at here at RV.net). Small tie wraps can be used to hold the brushes in place. I found a suitable bearing at Granger, and drilled the bottom cover to give the moisture that inevitably makes its way in, a way out.

[DWeikert]

racedrvr wrote:
Hi Dan, I had used the jack two times just a couple weeks before it "stuck" so I thought it couldn't be "seized". I just didn't think it had had enough time for that. I put a rag on the motor output shaft gear and grabbed it with a small pliers. It didn't take much force for it to loosen up. I then hooked up a 12 volt power supply to the motor and ran it a few minutes in each direction. It ran fairly smooth from the beginning and seemed OK. I put everything back together and ran the jack up and down enough to put normal loads on it and again, it ran fine without any unusual noise or vibration. There had to be some moisture down in the motor bottom bearing to cause it to "stick" so I suspect it's just a matter of time. But for now it looks like I am OK.

Thanks for clarifying. A good nudge could've been anything from the pliers you used to a pipe wrench and a breaker bar. 🙂 I'll give the pliers a try next time I have problems, and I'm just a little annoyed with myself that I didn't give something like that a try before sending mine back.

[racedrvr]

Hi Dan, I had used the jack two times just a couple weeks before it "stuck" so I thought it couldn't be "seized". I just didn't think it had had enough time for that. I put a rag on the motor output shaft gear and grabbed it with a small pliers. It didn't take much force for it to loosen up. I then hooked up a 12 volt power supply to the motor and ran it a few minutes in each direction. It ran fairly smooth from the beginning and seemed OK. I put everything back together and ran the jack up and down enough to put normal loads on it and again, it ran fine without any unusual noise or vibration. There had to be some moisture down in the motor bottom bearing to cause it to "stick" so I suspect it's just a matter of time. But for now it looks like I am OK.

[DWeikert]

racedrvr wrote:

An update: The wiring was fine, and I plugged in a drive from a different jack at that location. It ran fine. I decided to take the assembly apart to see just what was wrong. The motor was stuck and wouldn't turn by hand. A good nudge on the output shaft and it started running fine without the "nuts in a blender" noise. I ran it for quite some time forward and reverse. I then put the drive and gears back together. That assembly then was run in both directions and it seems fine. I didn't take the motor apart, but I'll bet the bearings are on their last legs even if they aren't noisy.....yet. I know I am likely on borrowed time, but perhaps not. I'll probably get a spare for "in case". Thanks for all the tips and suggestions. This is a great forum with helpful people!

Interesting. I had disassembled the gear assembly and verified it was the motor itself seized, but I only tried to turn it by hand. If I may ask, how did you go about giving it "a good nudge"? All my failed motors are back for rebuild, but I have little doubt I'll have another failed motor to experiment with in a season or two.

[racedrvr]

RamTC wrote:
All the motors are the same and it's almost always the bottom bearing that falls apart. If you're handy, you can replace the top and bottom bearing and the whole drive assy is as good as new for less than $10. As soon as these motors give off the sound of nuts in a blender, it's the bearings.

An update: The wiring was fine, and I plugged in a drive from a different jack at that location. It ran fine. I decided to take the assembly apart to see just what was wrong. The motor was stuck and wouldn't turn by hand. A good nudge on the output shaft and it started running fine without the "nuts in a blender" noise. I ran it for quite some time forward and reverse. I then put the drive and gears back together. That assembly then was run in both directions and it seems fine. I didn't take the motor apart, but I'll bet the bearings are on their last legs even if they aren't noisy.....yet. I know I am likely on borrowed time, but perhaps not. I'll probably get a spare for "in case". Thanks for all the tips and suggestions. This is a great forum with helpful people!

[kjenckes]

I went through this this past spring. I did all of the motor, cleaning, lubrication stuff and it turned out that my electrical converter was bad. My fan would come on and the fuse would trip. This only happened with the jacks. Replaced the converter and the jacks work fine.

[garbonz]

Buzzcut1 wrote:
Just a suggestion. If there is a water intrusion issue with the Happijacks instead of a plastic bag get get some of the lightweight small dry sacks for kayaking and ziptie them in place below the power head. waterproof and durable

Got any ordering or infor on these dry sacks? I am not familiar with them.

[garbonz]

JimK-NY wrote:
I just had to replace a motor on my 5 year old camper. I have only taken the camper off the truck a half dozen times so I was surprised and not at all happy to need a replacement. I could not see any signs of water or other damage.

Doesn't matter how many time you use it, it's water intrusion from rail/road spray that kills them. If you only use them a few times then just get a socked and drill and do it manually.

[garbonz]

Haooijac Motor covers seem to be prone to leak. Saved a bunch of $$ on my 10 YO Bigfoot cause he jac's blew fuses and the orig owner did not know what to go.

The o ring seal in the motor cap is hard to fit right and fails. You really have to keep them covered or the water gets into the gear head and runs right down into the motor. Shorting and corroding the motor. I agree it is a poor design, and they don't seem to care, just sell you a new one.

[JimK-NY]

I just had to replace a motor on my 5 year old camper. I have only taken the camper off the truck a half dozen times so I was surprised and not at all happy to need a replacement. I could not see any signs of water or other damage.

[hedge]

What I've found that works well are the triple gang plastic covers for electrical boxes (part of the vapour barrier), pretty much the perfect size to go over the motors. The plastic is more durable and they are cheap.

So far I just zip tie them on for the winter but maybe I'll think about leaving them on year round, although I don't think it will look very good.

[Buzzcut1]

Just a suggestion. If there is a water intrusion issue with the Happijacks instead of a plastic bag get get some of the lightweight small dry sacks for kayaking and ziptie them in place below the power head. waterproof and durable