MP Sprinkler Head Rotors

[bostonman]

Odd question, but feel this falls under "automation", however, it also applies to anyone with an irrigation system.

I have PGP (the company name) MP rotators for my irrigation system. Last year I had one of them swapped for a larger size, so I have this one as a spare/junk one.

In order to adjust the turning amount (mine are 90 degrees to 270), a special tool is required, but appears to be nothing more than pushing down on the silver part and turning it. The "radius" (the distance it throws the water) is adjusted by a small screw on top.

Yesterday I began wondering how these little things work, so I attempted to dismantle my spare/junk one but can't figure out how to dismantle it (I turned the tiny screw on top several turns but it didn't seem to loosen anything). Also, from what I see, I can't figure out how these adjustments change anything.

I assume the screw turns some valve internally which changes the amount of water, but I can't figure out how turning the silver dial changes the rotation.

Has anyone dismantled one to see how they work or understand how they work?

[wraper]

I assume you talk about Hunter products. PGP is rotator sprinkler and is not compatible with MP rotator head (needs PROS series sprinkler). For MP rotator no special tool is required, you can rotate it by hand to adjust angle and use flat screwdriver for adjusting distance. MPTOOL just adds a little bit convenience. In MP rotator water basically flows along the grooves on that rotating mushroom like thingy. Angle adjustment just adjusts radius of an opening from where the water comes in to supply flow in those grooves. AFAIK you cannot take them apart non destructively.

[bostonman]

I assume you talk about Hunter products.

Oops, yes, you're correct.

you can rotate it by hand

I assumed the tool wasn't required, but was afraid to turn it in case the tool disengages something (such as pushing down and separating the silver from the inner plastic) because I assume if it's rotated, the gears are being forced.

Either way, I can't figure out how turning that silver dial changes the angle. The teeth are all the same size, the inner plastic has all the same sized channels, and I don't see anything that changes when I rotate it.

As for turning the screw, the irrigation company told me if you turn the screw too much, the head pops off. This irrigation company has a habit of telling me false information, but wanted to see how many times before the screw pops out and I couldn't get it to pop out.

AFAIK you cannot take them apart non destructively.

This is the conclusion I came up with. I don't know if this has gears like the PGP rotators, or the water just flows through chambers.

[wraper]

The teeth are all the same size, the inner plastic has all the same sized channels, and I don't see anything that changes when I rotate it.

Because mushroom like thingy has nothing to do with radius adjustment. It's just for forming different beams of water. Quite clever system.

[bostonman]

It looks clever and I'm trying to figure out if it has any guts such as gears or what makes it rotate.

[bostonman]

I found a video:



He doesn't explain how he disassembled it. Looking at the guts, I assume the silver ring covers part of the openings where the water comes in and the water goes through the spirals causing it to spin.

I turned the adjustment screw CCW many times and it didn't come out. Looking at the video, it looks like it's threaded, but I couldn't get it out. Maybe it comes out under pressure?

[wraper]

Groves emit water jets under angle in direction opposite to rotation. So I assume force used for rotation comes from those, not some mechanism inside.

[bostonman]

I fully agree with you. Initially I thought these were intricate watch type devices with tiny gears, but seems it's an elaborate design of channeling the water to spin it.

One reason I've dove into this: last year I had irrigation installed with a three-year warranty on parts/labor and they installed several MP rotors. At the time I felt they didn't do much for the area they covered. They swapped some without changing the installation price and told me if I felt the others weren't enough, they'd return to replace them.

Well, I wasn't happy with a few others, called, and they wanted to charge to swap them with the PGP ones (approx. $60 per head swap). Now I have one that barely shoots water (it's got slightly better), but the company wants to charge $125 for a "service call" to replace any broken heads (I also have a PGP that's turning very slowly - takes about seven-minutes to do 180) that are "in warranty".

At this point I feel it's worth it to remove the MP head (it unscrews from the body) and clean the filter along with seeing if any dirt is blocking the area the water comes out of.

Also, the company doesn't seem to provide any post installation support without charging a ridiculous fee, so seems worth it to just start doing my own repairs. The PGP that turns slowly I plan to check the filter, or wait until they turn on the system next year because they will replace it without charging providing it wasn't hit with the lawnmower.