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I have about 50 Nelson 6000 rotors in my yard and many of them do not retract fully. I have determined that the retraction spring is just too weak to retract the head fully. Everything else about the rotor is working well. The seal is the newer style and not binding against the rotor due to shrinkage of the seal.



I would like to replace the spring with a stronger one, but Nelson/Signature does not offer it as a replacement part. However, Hunter does list the spring in the PGP model rotor as a replacement part.



I expect most people would just replace the head, but the spring is less expensive and would require about the same amount of work to replace as replacing the entire rotor. The little extra time needed is not an issue since I have more time than money for this project.



So, does anyone know if the Hunter PGP retraction spring would work in a Nelson 6000 head?

When the spring pulls the rotor down, the water in the rotor body is forced out the nozzle. If the spring is too weak to pull the rotor down, the residual water in the pipe and rotor body is holding it up.

@Wet_Boots:

My water comes from my well so my water costs are minimal. Secondly, what I spend on water is irrelevant since I would spend it whether or not I bought new rotors.

Remember that there is friction in the seal or it wouldn't be much of a seal. Also, if gravity was enough to pull down the rotor, then the spring would not be necessary, yet every rotor has one and many are criticized for not having a strong enough spring. Hunter makes a point of saying in their literature that they have a heavy-duty spring. When I lightly step down on the rotor, it goes down without much effort and the water in the casing sprays out. If I lift the rotor without water in the casing then let it go, it retracts all the way with the weak spring, so yes water in the casing can hold it up.

I am an engineer who has been trying to make the aging Nelson springs work for several years without success. I have also been unable to find a suitable replacement. Some of us would rather fix what is broken if possible and economical rather than just throwing away otherwise perfectly functional equipment. I just became aware today that Hunter springs are available as a replacement part so I thought I would ask if it would work. Hunter does list the spring as a replaceable part and they can be ordered, so yes they will help their customers with repairs.

My question was whether or not the Hunter spring will work in a Nelson 6000 rotor. If you don't know then your contribution is not helpful. Belittling me and treating me as an idiot when you know nothing about me is not appreciated.

@Wet_Boots: Reread what I wrote more carefully. Your comments indicate several misunderstandings about what I wrote.

Quoted from "Wet_Boots"

DIY-Dan: Remember that there is friction in the seal or it wouldn't be much of a seal. Also, if gravity was enough to pull down the rotor, then the spring would not be necessary, yet every rotor has one and many are criticized for not having a strong enough spring. Hunter makes a point of saying in their literature that they have a heavy-duty spring. When I lightly step down on the rotor, it goes down without much effort and the water in the casing sprays out. If I lift the rotor without water in the casing then let it go, it retracts all the way with the weak spring, so yes water in the casing can hold it up.

Wet_Boots: No, friction holds up the heads, because heads will stick up even when all the water has drained out

I agree that friction can and does hold up a head in the majority of cases due to sand/grit embedded in the seal or a shrunken seal causing binding on the rotor shaft. There are other cases where other forces working within the rotor besides the obvious ones (friction, gravity, and spring potential) play a role when the spring potential is marginal -- those are the cases I'm talking about. I could give you a detailed engineering analysis of the forces, but that would require much more time than I care to devote to it here.


In my original post, I never said that the head was stuck all the way up, or that all of the water drained out -- I said that it did not fully retract -- an important distinction since it puts all forces besides the obvious ones in play. IMHO, a properly selected spring should have enough potential (strength) to not only fully retract the rotor in a real-world dirty environment, but to firmly seat it in the retracted position to seal out dirt, debris and roots. Yes I know there is a balance between the spring strength and the minimum water pressure that will extend and operate the head. A young Nelson spring works well in nice clean conditions, but as it ages or friction increases due to dirty seals, the rotor too easily fails to fully retract, which allows larger dirt and grit particles to get into the seal eventually causing the rotor to stick fully extended due primarily to friction, or more accurately, stiction.

Quoted

DIY-Dan: I have also been unable to find a suitable replacement.

Wet_Boots: Well, now you are losing credibility. These heads are replaced by PGPs every single day, because, after all, the Nelson heads were copies of PGPs.

Sorry, the credibility lost here is yours. You quoted me out of context. It is clear in the original post above that I was referring to a replacement for the Nelson spring not the head. The previous sentence specifically states "Nelson spring".

Quoted

Wet_Boots: Your ideas about what companies should provide are certifiably hilarious.

I'm glad you had a good laugh, but again, reread what I previously wrote - I didn't write anything about what a company should provide, I stated what Hunter's PGP service information states that they do provide.

We both agree, as I originally stated, that most people would just replace the head, but if that's what I wanted, I wouldn't have opened this thread and asked my question since there are numerous existing threads with head recommendations.


So enough already!! I apologize for wasting your time and I regret wasting my time here with my "hilarious" question. Yes, it was indeed a teachable moment. I will consider this thread closed and seek an answer to my original question elsewhere.

Just buy one and try it..