Re: NAA lift won't move

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Posted by Kevin on April 27, 2017 at 11:09:55 [URL] [DELETE] :

In Reply to: Re: NAA lift won't move posted by JMOR on April 27, 2017 at 00:50:57:

Thanks for the drawing, JMOR. Wish I had started with this insight. It's so obvious when you have a clear drawing in front of you!

For now, I'm assuming that the problem is that the valve cracks open too easily. Maybe the spring is broken, like you suggested. Or it's just fatigued. I don't know. Seems like it should have a fairly happy environment in there. It's hard to imagine a lot of failure modes.

Anyway, went to the hardware store this morning and spent 10 $ on various springs. I'm going to add a spring under the acorn nut. Have several different spring constants (wire gauge, material, etc) and I'll just trim the length to get the right force. I'm fairly sure that making the spring too strong will compromise the function of the lift. Have no way to really know if it's right. Seems like blocking most of back-pressure flow (with my finger) caused the lift to rise above the position indicated by the control lever. Maybe I can use that to test my work.

If I hold the o-ring-contact end and pull on the threaded part, I hear a click. If I push, I get another click. When I look into the acorn-nut side, I see something that looks like it could be a retainer clip but there's no holes for removing it. Point is that I don't see how to service this and I don't have an extra to reverse engineer.

Should any fluid leak out when the acorn nut is off? I can see that there's a spool that blocks off the outlet tube. In the picture I posted last night, you can see the valve with the spool stuck open. I'm assuming that there's clearance behind there, back by the spring JMOR drew. So with normal pressure, open or closed, there could be some fluid seeping out of the acorn-nut end of the valve, right? I would assume that when the valve is open, quite a bit more fluid would seep. When I observed it in the stuck-open state yesterday morning, there was a healthy flow of fluid out the acorn-nut end. Now that I'm thinking about it, there would be no need for a copper seal unless there was fluid back there. Probably isn't important---just thinking about all the observations and trying to make sure it's all making sense.

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