HW OBoy Rebuild Question #2

[ElectronGod]

I have rebuilt my OBoy and fixed the leaky check valve issue that I posted about in a different thread. I have another question.

What is supposed to happen as you're pumping and the ram reaches the end of travel? Should the handle be able to be pressed through so that it lays horizontal? I thought that was the purpose of overload valve? Mine will move a little bit but I can't get it to go all the way.

I did not mess with the overload setting during the rebuild. If I wanted to check it, how would I make the adjustment? That have that weird nut way down in the hole.

Dale

 

[Hiball]

I see no benefit from attempting to force the overload to open with the pump. Handle while it’s locked up on the top end, it’s a good way to tear stuff up and wreck that pump seal. I say that because your assuming that the pressure or lack of pump handle movement is exceeding the overload setting. I don’t doubt with a long enough lever you “could” exceed it, but at what cost and what would you learn?

 

[ElectronGod]

I guess what I'm asking is if this is an indication that the overload is not working correctly?

 

[Hiball]

I guess what I'm asking is if this is an indication that the overload is not working correctly?

Absolutely Not... Without a test station to know what tonnage your lift arm is lifting, your best option is go with the factory setting. Now... if some donkey had been in there randomly making adjustments and the jack won’t lift anywhere near tonnage. It’s now time to make adjustments, Will the jack lift a load?

 

[ElectronGod]

I'm guessing there have been no Donkeys in there since it does not look tampered with. The factory did a good job Donkey-proofing that setting with the special screw.

I have not tired lifting a load yet. I still want to paint the pump before I put it back in the jack. During the refill and bleeding process I noticed that once the ram hit it's end of travel the handle would stop wherever it was in its stroke. I assumed the overload would open to prevent damage to the pump seal.

I will put it all together and see if it lifts (and holds) a load. At least it isn't leaking oil all over the floor now.

 

[Hiball]

I'm guessing there have been no Donkeys in there since it does not look tempered with. The factory did a good job Donkey-proofing that setting with the special screw.

I have not tired lifting a load yet. I still want to paint the pump before I put it back in the jack. During the refill a bleeding process I noticed that one the ram hit it's end of travel the handle would stop wherever it was in its stroke. I assumed the overload would open to prevent damage to the pump seal.

I will put it all together and see if it lifts (and holds) a load. At least it isn't leaking oil all over the floor now.

Yes the splined head adjusting screw is a OEM factory head to prevent “unauthorized” service centers from servicing the jack, albeit easily overcome.

 

[ElectronGod]

I have the pump back together (for a second time, it leaked a little after the first). I have it filled with fluid and bled (I think). I can pump it up and release and it lowers. I put it under the rear end of my truck and it seems to have very little lifting ability. Pick up the read end till the tires are just about to leave the ground and it gets REAL HARD to pump!

Any thoughts?

Dale

 

[Hiball]

I have the pump back together (for a second time, it leaked a little after the first). I have it filled with fluid and bled (I think). I can pump it up and release and it lowers. I put it under the rear end of my truck and it seems to have very little lifting ability. Pick up the read end till the tires are just about to leave the ground and it gets REAL HARD to pump!

Any thoughts?

Dale

It’s hard to judge “really hard” over the interwebs, but maybe some info such as what type of “truck” your lifting. The oboy has a 2500lb lift capacity, attempting to lift the entire rear end of a pickup could definitely be near max capacity, which would explain the force required to lift the load. I would either attempt to lift a lighter vehicle or work on one side of the truck, versus both to see if the force required is diminished.

 

[ElectronGod]

I did some more bleeding and heard more air escape when I loosed the fill screw on the side. It def worked better but is still harder than I remember. I was able to lift the drivers front corner of my F-150 off the floor and it held over night. Only dropped 1/4".

Maybe I should be asking for proper bleeding procedure? Is there a proper method?