Coast Resorts Open Roads Forum: Truck Campers: Happijac lubrication


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bigfootford

Fair Oaks, California

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Posted: 08/14/10 09:55am

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tr3rt wrote:

how can I get this write up?

Are you talking about the jack lube procedure?

Here the link, which is in the Truck Camper University - Free Online Schoolin'

Click below:
HJ lubrication procedure

Jim

* This post was edited 08/14/10 10:03am by bigfootford *

2000 2500 9.6 Bigfoot,94 F250, Vision 19.5, Mich 245/70XDS2's, Bilstein shocks, air bags/pump, EU2000, PD 9260,Lifeline 100ah, 200W. solar, Morningstar Sunsaver 15A/ display panel, Trimetric, Delorme/laptop, Holux gps rec,led lights, Wave-3 heat.

MTBob

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Posted: 08/14/10 07:28am

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jjinatx wrote:

MTBob,

Thanks for the great info on the jack motors. While I have the motor off the jack,I'll go ahead and check that clutch for any damage.

As for the jack itself, I wire brushed the whole screw thread and coated it with the white grease for GD openers. I ran it in and out a few times, each time wiping off the threads because first time when I backed it out the grease looked tan (rust?). I recoated it once more and ran it in and out. It is well lubed now and I can turn the acme rod with my fingers.

I thought about repainting the inner leg, but the finish is in pretty good shape, so I just waxed it good with Johnson's paste wax.

Be sure to clean and re-grease the gear train in the head. I wouldn't put grease in the ball clutch, just a light coat of machine oil will do. Lubriplate grease is a good choice for the gear head.

HJ tech support suggests not using a grease on the jack threads, but rather use an oil coating. I disagree with that recommendation and used a Stay-Lube Marine grade wheel bearing grease, made by CRC. It's a blue grease, a little thicker than Lubriplate and is designed to repel water. Like you did, I coated the threads and then wiped them so there was only a light coating remaining. Either Stay-Lube or Lubriplate is a good choice for coating the thread.

Bob
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jjinatx

Austin, TX, USA

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Posted: 08/14/10 06:32am

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Current Rig: 2017 F350 Crew Cab Short Bed 4X4 Powerstroke, 2018 Grand Design Reflection 29RS. Dearly Departed: 2003 GMC Sierra 3500 Dually, 2002 Bigfoot 25C10.6.

tr3rt

Lake Odessa

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Posted: 08/13/10 07:44pm

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how can I get this write up?

MTBob

Montana

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Posted: 08/13/10 09:44am

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I'll add a bit more to KKELLER14K's excellent thread on HJ maintenance regarding servicing the motor.

The motor is a simple DC power drive, with a permanent magnet stator. It is important to check the motor for several points: 1) commutator wear, burning or degradation, 2) brush wear, 3) bearing lubrication.

Motor disassembly is simple, just remove the two long screws holding the commutator and end bearing. Check the commutator for wear, burning or glazing. It's a good idea to remove any glazing with a 400 grit sand paper, making sure to remove all residual grit after cleaning. I used a lathe to turn the armature. If there is any burning on the commutator or wires, you may need another motor. See photos.
Commutator showing minor glazing
[image]

Cleaning commutator on lathe
[image]

The length of the brushes is important. I'm not too sure how long they are when new, but they shouldn't be shorter than, say, a 1/4" or so. Inspect the brushes to see if they are still solid, with no broken pieces. Here's the tricky part with the brushes - holding them back in their brass holders while inserting the commutator / armature in the end bell bearing. To make this easier, I made a couple of small brass clips that hold the brushes in place while inserting the armature in the bearing. See photos.

Inserting Armature into brush housing using clips
[image]

Brush restraint clips
[image]

Now comes the tricky part. When you insert the armature in the stator (motor housing) the magnet will "suck" the armature into the housing and pull the commutator from the end bell. So, I connected a small screw type hose clamp to the end gear on the armature (see photo) to hold the armature in place while assembling the motor. It worked great.

Hose clamp on armature gear end to hold end bell in place
[image]

Note that the wires coming out of the end bell are not sealed. I placed a small amount of sealant in this hole to make sure there would be no water intrusion.
[image]

Regarding bearing lubrication - be sure to note any shims (thrust washers) that come out of the lower and upper bearings and replace them EXACTLY the way they came out. Lubricate the bearings with a light machine oil, making sure that the bearing surface on the armature is not scored and/or burred up too much. If there is scoring or burring you may need to replace the motor (or machine the armature bearings and replace the bearing inserts - not too easy).

* This post was last edited 08/13/10 08:50pm by MTBob * View edit history

MTBob

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Posted: 08/13/10 09:15am

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jjintax: The popping sound you heard in the jack was the friction clutch balls moving in their seat. This clutch is part of the gear head assembly. There is a circular spring that hold three balls that sit in a depression on the clutch gear. The tension on these balls is determined by the pressure created by the shake proof nut holding the circular spring and balls on the gear. See photos. When the jack screw becomes dry and stiff, more torque is required in the gear train and the balls click in the clutch. Initially I wasn't sure how to set the tension on the shake proof nut, so I measured the distance with a micrometer to approximate the torque setting on the spring. See photos. Subsequently, I learned from HJ tech support that there is a torque setting for this nut. I can't remember what it is right now, I'll need to check my notes and see if I can follow up (I think it was around 9 inch/pounds)(Edit: I checked my notes and HJ tech support said to use 9-10 inch/pounds on this nut). Using the distance measurement method worked pretty good. I needed to increase the torque on one jack after I assembled it.

Gear Assembly
[image]

Clutch, showing balls on gear drive
[image]

Clutch, gear nut setting with a micrometer- better yet, use 9 10- inch/pounds of torque on this nut
[image]

* This post was edited 08/13/10 03:18pm by MTBob *

bighatnohorse

Cave Creek

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Posted: 08/13/10 07:15am

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I bought some used happijacs from a dealer that have the quick release.
These jacks are so well lubricated that the extension would start to extend on it's own from gravity when the quick release lever was activated.
IMHO, that's the way they should work.

Also, inspect the top of the motor housing cap.
The cap can develop a hairline crack which permits moisture entry - and is the beginning of the end for the jack.
Think "Eternabond".

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KKELLER14K

BEAVERTON OREGON

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Posted: 08/13/10 03:50am

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Thanks all you guys...really trying to help out here and the stories make it worth the time to shoot all the pics, edit and get out the word as to what the heck goes on with these jacks. The truth shall set you free! I guess I should be the guy in the tech support to offer up the solutions to fix the failures.

jjinatx

Austin, TX, USA

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Posted: 08/12/10 09:31pm

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After soaking with Blaster, I got my Acme screw unstuck. The Acme rod was bone dry and at least the top 12" was rusty. If HappiJac thinks they are "lifetime" lubricated, I hope they don't put those guys in charge of our new national healthcare. I see no remnants of grease anywhere along the Acme threads.

Does the Acme rod come all the way out? I backed mine out as far as it would go without forcing it. I measure the exposed rod at around 33", which is the same as the distance from the bottom of the inner leg to the red "eek-you've-gone-too-far" label.

A tip for backing out the rod: If it is sticky like mine was, instead of buggering up the square end with a wrench, I stuck about a foot of 1/4" hot rolled round stock through the hole in the shaft and used it as a "T" handle. Lots of leverage and no slipping. A phillips screwdriver would probably work too.

As for new grease, I'm thinking about the Lubriplate white grease I use on my screw drive garage door opener.

Also, it "seems" that the part of the rod that was rusty is equivalent to how far my jacks are extended when the camper is stored. I set it down on a 2' high, 4'x8' platform, but I extend the jacks down snugly to the ground just for a little added stability. Maybe that leaves it exposed to moisture, so I'm thinking from now on I'll retract them all the way.

One last question. Does anyone have the cutaway pictures that 54suds posted, or know where they got moved to?

I'll definitely be tearing apart the other 3 jacks after seeing how bad this one was.

-jj