Estimate of pull-out wire/cable force A-602

[billcobb]

OK, now have a last detail to address on my recently raised A-602. I'm using the original solid wire to draw down the pull-out lever up top. At the base, what is the approximate force required to pull in the tail and push on the brake bolt head ?

I've seen some drawings and photos of pull-out levers at the tower base and they seem pretty long (36") and the lever ratio is 5 - 10 : 1 (which seems like a high amount of force). On my Bakers and F&W's I use winches to do the job. On a Star 26 I have a lever that's about 24" long with a lever ratio of about 4:1. I can set it with 1 arm pull.

The original tail spring is in place on the lowest setting on the tail bone. Does all this seem reasonable? I think I have another tower winch in the junk parts cabinet, but that would mean replacing the wire or splicing in a length of cable.

Tomorrow I may use a come-a-long with a fish scale to measure the pull-out force. What's a guess on how much I should expect. My fish scale is as old as the mill and we don't want anybody to get hurt !

[CTXmiller]

My A702 is a two arm job to pull it out of the wind. No estimate on force.

[Bryon]

I wouldn't use a winch. You can put too much force on the cut-off wire/upper furl. I would use a proper Aermotor style cut-off handle for an 8 foot mill. Make sure to mount the handle on one of the two legs of the tower opposite where the upper-furl is mounted.

[windybob]

we usually use 2 foot handles. However for an 8 ft mill, a 3 foot should suffice. Much depends on where the wire hooks to the pullout lever.

[Ron Stauffer]

Real 8' Aermotor furl handle - 24" length, 1" from end to bracket pivot, 8" from bracket pivot to wire pivot, and 4" from bracket pivot to wire attachment in closed position. Dealer cost is $25 for a furl handle so it was one of the things added to the list of purchasing versus fixing. Once the furl lever is against the two attaching mast pipe bolts, it wont go anymore.

Ron Stauffer
Montrose CO

[Dave Straub]

I agree with Bryon not to use a winch, you will end up bending the furl mechanism parts. It really helps to take an oil squirt can with you when changing oil and oil the vane pin and everything else that moves. It will make it easier to work the handle.

[billcobb]

Breakout force is about 100 lbs, which then drops to 80 lbs as the tail starts to move. This drops to 60 lbs and lower as it approaches full closure because of the increasing mechanical advantage of the furl rod angles. I need to measure displacement of the cable to set the position of the cable tie on the lever to get the right action (furled to brake).

I originally thought the vane seemed bound up and this furling system was a bit hoaky, but I'm convinced that it works pretty well.

BTW: I've put a stiff spring under the brake band bolt head so that it acts as a cushion for the furl arm contact with the brake mechanism. Not sure how long that will survive, but at least for my lifetime...

[Aermotor Fan]

I have never had a problem with using a windlass.Aermotors furl system is not that
weak. I like using a windlass You can pull in the tail in degrees,Instead of full open or
closed.
Adam

[LoTec]

I like using a windlass You can pull in the tail in degrees,Instead of full open or
closed.

I think it is a very bad idea to only partially furl an Aermotor ("pull in the tail in degrees,instead of full open or closed").

In a high, gusting wind situation, the mill governs itself by changing the angle of the wheel to the tail. The mill has a buffer device (659, the part with the fat compression spring) to act as a shock absorber as the furl angle changes. That shock absorber is designed to hit on the main motor casting at either extreme of its travel. If you have the mill halfway furled, and the governing action causes the tail to completely swing to its "closed" position (parallel to the wheel), then when the gust dies down and the governor spring tries to swing the tail back to the "open" position, the tail bone will strike forcefully against the 585 tailbone casting, instead of the buffer striking the motor and transferring the force of impact to the buffer spring.

This is a good way to bend the tailbone or break the 585 casting or a 528 furl arm.

[Kevin]

I concur with LoTec on keeping the Aermotor half furled is not an optimum plan.
I would add that keeping the windmill open will keep the whole assembly balanced and it will yaw much easier.
A windmill that is furled, keeps a lot of side pressure on the mast pipe. This adds drag when a shift of the wind direction puts added pressure on the windmill.
The Aermotor will hang like a plum bob from the center point of the pitman guide (centered of the mast pipe) when it is open. Furl it and it will roll over. Ask anyone who tried to put one on a tower while it was furled.
A furled windmill also wears out the mast pipe on one side and possibly bends it.
I’m sure other might disagree and I respect those guys in more windy areas.
What say ye?