Floor jack valve

[dd5]

I've got this old Sears 2 ton just about figured out. Turning the handle feeds the square core down on a ball bearing. Is that bearing supposed to seal against the metal seat below? There is no O-ring down there (or in exploded view diagrams I've seen). That seat appears to be a solid part of the body, i.e. not a moving piece.

What am I missing here? The release valve isn't holding and there are no leaks anywhere.

 

[5ubtle]

You might get better responses here if you can post pictures, exploded diagrams, schematics, etc.

*If* I understand what you are asking; yes, the ball bearing and it's seat form a valve (the ball seals against the seat).

By "The release valve isn't holding", do you mean that the ram won't stay up when loaded?

 

[dd5]

The ram fails to lift the jack. Unloaded it goes up, but If I put 160lbs (me) on it, it goes down.

I know tubing flare fittings form a metal to metal seal, but much softer metals. I think I'll try an O-ring down there.

 

[mm08822]

More likely, the piston rod seal is breaking down. Fluid is able to bypass it allowing jack to creep down.

Search "Sears floor jack" for related threads.

 

[dd5]

Inspected the "master cylinder" (pump rod). There is a shaft seal to keep **** out of it. Below that is a spacer and an O-ring. If that O-ring was failing I should see oil leaking up out of it. There is just the small amount you would expect to see.

Since that pump works at any lever angle, there must be a one-way check valve to **** oil in between strokes. I'll have to study a diagram to find it.

 

[ajchien]

The hcrcnow.com website has a decent catalog of hydraulic jack diagrams you can search through. Sears has rebranded many jack designs over the years, so it’s kind of hard to guess what jack you have without seeing it.