Aermotor A602 has me stumped

[tom b]

OK team I am all ears. Neighbors windmill, early A602, new babbitt poured 6 years ago, oil never changed in last 5 years!! I climbed tower and to my amazement gear case had plenty of oil. His complaint was the windmill makes a "clicking" sound in certain wind conditions and when it clicks, it is twice per revolution. Mill is a display and not pumping water. Noise is not there all the time. First thought was pitman arm lower bearing making noise on top dead center and bottom dead center due to bearing wallowed out. Second thought was shaft at yolk worn doing the same even though no bearing in the yolk. Turns out pitman's were fine as well as cross shaft in yolk. The mill actually "jumps and bangs" slightly when making noise. Tried to use a screw driver to my ear to pinpoint noise but no joy. Checked bull gears and teeth look to be in great condition. Noticed pitman gears had roll pins not solid pins that were not flush with base of tooth and looked to be burred up.
My thought was the bull gear tooth tip was hitting the long roll pin ends and actually slightly lifting the gears slightly.
Used a die grinder with rotary file and dressed all four pins flush with base of pinion gear. Again no joy.
Had a beer, scratched my head and watched rotation of wheel for a while. I can actually feel the mill slightly shake when it makes the noise and the noise is transferred to the galvanized sails and tail to produce a thud and loose sheet metal sound. Checked all wheel nuts and bands and everything tight. This one has me stumped
Any thought from Windy or other 602 gurus?
Frustrated in California,
Tom

[Bryon]

If the sound is "twice per revolution" of the wheel (blades), I would focus on the blades. Maybe there is a loose spoke where it hooks through the hub. Nothing else I can think of would make a noise twice per wheel revolution but the wheel. It could also be a loose clip on a blade. It could shift once on its way up and again on its way down.

[PaulV]

Perhaps it's the pitman guide wheel shifting from one side of the hoop to the other.

[windybob]

I would guess that the oil scraper inside the hub may be thumping on the plug area. However the 2 per round thing has me stumped. That would rule that out.
I will sleep on it.

[windybob]

What you might do, is to check the spokes on the rear of the hub. I've see them interfere with the brake band before.

[tom b]

Thanks for all your comments. The oil collector was replaced by me last week as a precautionary move since I was on the tower and I did see evidence of minimal oil drips at bottom of brake hub. Noise did not change and original collector looked normal to me.
I like both ideas about wheel blades, clips and rear mounted spokes hitting the brake band. I have been concentrating on the gear case and ignoring the wheel. To date, all I did to the wheel is check the square nuts for tightness. I will go back next week and check all the wheel points both Bryon and Bob mention. Paul, I checked for wear on inside portion of hoop,(minimal wear) and guide wheel seems to perform normally when I removed bonnet and watched motion of the wheel. Guide wheel has no flat spots or worn areas from lack of oil. I will get back to you after I re examine the mill. Thanks again for your reply's,
Not quite as frustrated in California, Tom

[windybob]

ALso, check the inside of the helmet for rub spots. things fit really close in there.

[MAS]

Hey Tom. How have you been? Just put up # 8 in my collection have 3 more in the works.
Mike

[tom b]

Hi Mike! Poway is still waiting for your comeback. #8 up and running huh, got me beat as I am culling the herd and sold off most of my standing mills. You made the right choice years ago in leaving California.
Down to two up and probably 7-10 on the ground needing restoration plus lots of parts. I would like to part with what is on the ground and my parts (as one package), but of course you have first choice. I am getting more into steam 7 1/2 gauge, 1 1/2" scale locomotives and spending more time at live steam clubs. I will probably downsize in the next few years and get out of California. You are still my hero with your precision bearing Samson open gear mill.
Have a great holiday season with your family and livestock,
Tom

[Smax]

That is a beautiful open gear samson Mike