Super Lift 3 ton Jack Help

[jacked_72]

This is a rapid pump floor jack. I thought I had it working, but while it will go up and down, it will not hold anything. If I stand on the jack when pumped up, it will go back down without opening the valve. The jack was used when I got it and I previously opened it up. The main cup seal looked OK (no cracks and it was pliable). The tonnage adjustment screw, however, had been screwed all the way in, however. There was about 1/4" of oil over the adjustment screw once I took the cover screw off.

I'm going to tear into it again, but I'm hoping someone can point me in the right direction as to which system is likely the issue. Is the main cup seal the usual culprit or is it likely the bypass valve system?

 

[Hiball]

I would verify that the working valve components are correct and your jack isn't simply working on the high side, which isn't designed to hold any weight. Next.. Since you have the overload completely closed and there is still oil on top, I would check to make sure those components are correct and someone didn't lose the tiny ball (if not a cone type).

Would also verify the release valve components.

 

[jacked_72]

Thanks, Hiball.

I've been through the valves, and I cannot tell for sure if all the parts are there, but they appear to be.

The release mechanism is a needle valve. No ball bearings or springs.

The valve directly below that had two balls in it: one large and one small. The smaller one goes in first and the larger one is on top of that. This valve has no springs in it.

The bottom valve had the screw top cover, adjustment screw, a heavy spring, a centering device and a small ball bearing.

I don't have a picture of the top (rapid pump) valve open, but it had the screw cover, heavy spring, centering device and small ball bearing as well.

After going throug these valves, the issue is the same. The jack will pump, but will not lift a vehicle no matter how far in the lower valve adjsutment is. With it screwed in all the way, the jack will hold my weight. If I back off a turn, it will not hold my weight.

Do you have a schematic for this jack? I thought there were missing springs on the first valve below the release screw that someone had lost parts, but I saw a picture of a disassembled jack in the overseas jack thread and it appeard to be set up the same way -- without springs. I'm open for suggestions. Is there some adjustment procedure that might need to be followed?

Thanks.

 

[Hiball]

I believe this one covers your jack.

Not all working valves utilize springs or weights, I would double check to make sure when you installed the "little" ball on the overload and quick lift valve that the ball was centered on the seat prior to dropping in the "centering" piece and heavy spring. I always use a dab of bearing grease to hold centering stem inside the spring when I drop it down in the hole.

 

[jacked_72]

I tore into the jack again last night and the only progress I've made is to make it so that it won't pump at all. Initially, I pulled out the ball/spring assembly for the over pressure portion of the system and made sure that the centering piece was on the ball correctly. Once I did that, I buttoned it back up and could lift a 200 pound person, but not a vehicle. I left the cover off of the over pressure adjustment screw and noticed that there was no oil on top of the adjustment until I tried to lift a car. Then, the oil filled in over the adjuster. I tried tapping the ball bearing with a punch to reseat it and got the same result.

I kept removing valves and balls in order to make sure there was no debris in passage ways and in the process lost a lot of oil. The last time, I replaced the lost fluid with new, but couldn't get the jack to pump at all. I could pull the ram out, but the pump would not extend the ram. I went through trying to bleed it a bunch of times and got nothing for the trouble. The thing just refused to pump up. I had this same issue when working on it earlier, but I was able to extend the ram and bleed the jack to get it working. When I was able to get this procedure to work, the jack would slowly bleed down with no weight on it and the release valve fully closed. Eventually, the jack would stay up and not bleed down at all.

Finally, I pulled the whole thing apart, thinking the main seal might really be bad after all. I still don't see any cracks or obvious defects with it, though there are some scratches below the lip (which looks fine).

With the jack apart, I've been through the passages for the oil in the base. They all seem to be open. Operating the pump seems to send move oil, as it can be heard and seen if I don't put the covers on the various holes. I obviously don't know what is wrong with it, but my guess would be that the main cup seal on the ram is bad or the valve section which has the smaller ball bearing with the larger on on top of it is not working right. I presume that set up is some sort of a check valve system that allows oil to come in from the resovior and then allows it to be pumped into the ram sleeve to raise the piston. I can understand the smaller ball on the bottom being the seal, but the top ball just seems to sit on top of the smaller ball. Is it just a weight? If I have this right, I suppose the smaller ball may not be seating properly (in which a reseat might be in order) or the upper ball is not heavy enough to get the thing to seat properly.

Also, what is the purpose of the hex plugs in the side of the jack? They have a ball bearing underneath them. Are they just part of the drilling done on the jack in the manufacturing process.

Any thoughts? I'd like to get it working, but at this point I'm about resigned to the fact that it aint gonna and that this is more of a learning experience.

 

[jacked_72]

Update:

I finally got the jack to lift a car, but not via the rapid pump feature. If I leave the adjustment screw for the rapid pump backed so that it does not engage, the jack works like a regular jack and works fine. As soon as I tighten the rapid pump adjustment screw so that it engages the rapid pump feature, it won't lift jack, but it will rapid pump so long as it is not under load.

I have not played around with increasing the pressure on the rapid pump adjustment screw because I don't know how it is supposed to be adjusted. Does this sound like just an adjustment issue or does it sound like something more?