Wheel Balance

[hwy8]

I completely rebuilt an X-702 and put it on a 14' (or so) tower top which is plumb. It runs smoothly, the tracking of the wheel sections seem right-on, there's no bumps or jumps that show in the tail. Because it's in not much "good" wind (pretty deep in the garden), those times that it gets buffeted, it still runs nicely.

So, if I had a switch that turned off the wind "right now", the wheel would spin a few times, then come to a stop, and then, goes backward about a third of a rotation. Depending how fast it was going around in the first place, it then rocks back and forth until "the heavy spot" stays at the bottom.

This is the first time I've seen this happen. I can see the area that the wheel seems heavy and it wouldn't take much to hang a light tire weight on the opposite side. Is that what I need to do?

(I once carefully weighed B-702 blade sections and was shocked at how close the weights were to each other!)

[CTXmiller]

Windy Bob could answer that easy.

I’d put the weight across from the heavy spot on the other side, possibly adding an extra nut or two on the outer band bolt. Might consider adding the extra weight in a “Y” so you’d put two weights on. That Y could get it more of an even balance with the heavy spot being the bottom of the Y.

[hwy8]

I really like the "Y" shape idea! It could be fine tuned pretty easily with that little bit of extra weight on the outer band. If the machine was actually pumping water, there would be plenty of other stuff to pay attention to but it being so close to the ground makes me fussier.
Under just the right conditions, I can see how rotation in the wrong direction might happen.

[Todd]

The gearbox self balances because the yoke is at the top along with the pitman arms, and it will settle to the low side. The "heavy spot" is when the pitmans, yoke, and the bullgear bosses are at the bottom of the stroke. The only time you need to "weight" a wheel is on a direct stroke windmill that pumps every revolution of the wheel.

[Windcatcher530 Dan]

I have to agree with Tod

[Wayne]

I don't believe a windmill would ever turn backwards because of the way the blades are angled. The vane is always going to keep it into the wind.

[Bryon]

Todd is correct.

[Merlinn]

My A702 will spin backwards form a dead stop if hit from behind. It will do that until the tail turns it around. Then it will spin the correct way.

[windybob]

Sometimes a mill turns backwards a little, due to the water in the wellpipe going down to the weephole.

As far as balancing the wheel, I only balance an Aermotor wheel off the mill. If you have luck on your side, you can pull the wheel, shaft, and hub out of the mill or build the wheel on the hub and shaft only, put it in a horizontal (slightly tipped up at the front) pipe in a stand. Insert the shaft in there, and balance away where ther is no wind. Tack a weight on the out rail to conpensate.

There has been talk before about balancing a wheel already installed on a completed head. That's a big no-no. I won't balance because of the gearing of the mill, the internals are differnt on many strokes so the internals throw the weight out of kilter. If you put a rim-weight on, it won't be balanced on the next round, and the one after that. Most wheels we balance are off the mill, on a balancing stand. Of course, Aermotors have to be assembled on the hub. Once you balace it, make sure all you mainshaft components are lined up, and with help, install the mainshaft, hub, and wheel in the case. ( this is not for the faint of heart).