Vintage Windmill and Wind Generator Forum

Had to lower a 30 ft. Aermotor tower this weekend with A702 on top. The gear box was missing the fan and tail and badly rusted on the mast pipe. The mast pipe screw/bolt under the yoke was rusted off and the gearbox was not spinning on the mast pipe and wouldn't come off. I reinforced the bottom of the legs with 2x4s to keep them from bending when lowering. I then put some support under the 2x4s to steady the tower before taking out the bottom leg bolts. I eventually lowered the tower with the head still on tower, but my lift point shifted from the loop on gear box to under the mast pipe base on the tower. I had to make sure the bottom of the tower legs were off the ground a few feet before you lower the rest of the tower down flat or the legs would start digging into the ground. I used a front end loader on a tractor and slowly pulled the bottom of the legs out with a chain while lowering the top of the tower to the ground. It all worked out ok and I did't damage anything, but I thought there might be a better way of doing it. I almost forgot, a few storm clouds appeared and the wind picked up and a little rain came down just as I was starting to lower the tower. So, we had to halt everything until the weather cleared some.

I was wanting some feedback from real windmiller's about the best way to take one down safely. I have installed a few towers, and I have lowered a few gearboxes, but lowering a tower was new to me. What tricks are you using to keep the legs from hitting the ground while lowering the tower flat?

Any suggestions on the best way to lower one? Thanks, for the input. Forgive me if this question sounds stupid.

Jerry

Jerry not a stupid question. Better to ask and learn safe ways than to get hurt. Nobody needs that.

I've lowered 100's of towers with or without heads. I almost always hook the boomtruck winch cable and sling around the first girt under the platform. I use another winch, hand type on the other side of the tower fastened to my flatbed Dodge pickup. Then tighten both winches and take out the back anchor bolts. Cut one side of the anchor angle on each front anchor so the remaining side angle bends as the tower is lowered. This keeps the tower under control as it is lowered. Lower the tower until the head is same height as flatbed with old truck tire for wheel to rest on. Remove bolts, pump rod furling stuff and spread tower to remove mast pipe. OR pull head off mast pipe. Drive pickup forward to separate.

With tall towers or 2" size leg towers that are weak in design we use two 2-1/2" 20' angle irons one on each side of the tower with bottom end fastened to the bottom of tower leg, the leg still fastened to the anchor and top end to the opposite leg, the one with the bolts removed. Use vice grips and clamp 20' angle to every girt and cross brace that it intersects and at the top vicegrip it to the leg. This forms a triangle and will prevent the tower from wanting to buckle. Make sure every girt and crossbrace is intact on the tower sides.

To lower tower, the boomtruck winch is given slack and the hand winch tightens and towers starts to tilt over. The winches work together keeping both cables snug. Now after the tower is well over center the boomtruck winch lowers the tower and the hand winch is not needed. CAUTION.. Occasionally the anchor will be made out of hard brittle iron and it will not bend 90 deg. but will break. You need to determine this when cutting one side of the front anchors as how hard it cuts. As the tower is lowered you need to monitor the bend if it wants to crack.

Now with short towers 30' or less we usually just hook the boom cable to the side of the tower so 2/5 of the weight is above the hook and 3/5 below. Tighten the cable, remove bolts, careful when tower is raised up over the anchors it will kick sideways. Hold on to it and as the tower is lowered walk backwards and lay tower down.

Dave Straub wrote: Tue Apr 02, 2019 1:55 am I've lowered 100's of towers with or without heads. I almost always hook the boomtruck winch cable and sling around the first girt under the platform. I use another winch, hand type on the other side of the tower fastened to my flatbed Dodge pickup. Then tighten both winches and take out the back anchor bolts. Cut one side of the anchor angle on each front anchor so the remaining side angle bends as the tower is lowered. This keeps the tower under control as it is lowered. Lower the tower until the head is same height as flatbed with old truck tire for wheel to rest on. Remove bolts, pump rod furling stuff and spread tower to remove mast pipe. OR pull head off mast pipe. Drive pickup forward to separate.

With tall towers or 2" size leg towers that are weak in design we use two 2-1/2" 20' angle irons one on each side of the tower with bottom end fastened to the bottom of tower leg, the leg still fastened to the anchor and top end to the opposite leg, the one with the bolts removed. Use vice grips and clamp 20' angle to every girt and cross brace that it intersects and at the top vicegrip it to the leg. This forms a triangle and will prevent the tower from wanting to buckle. Make sure every girt and crossbrace is intact on the tower sides.

To lower tower, the boomtruck winch is given slack and the hand winch tightens and towers starts to tilt over. The winches work together keeping both cables snug. Now after the tower is well over center the boomtruck winch lowers the tower and the hand winch is not needed. CAUTION.. Occasionally the anchor will be made out of hard brittle iron and it will not bend 90 deg. but will break. You need to determine this when cutting one side of the front anchors as how hard it cuts. As the tower is lowered you need to monitor the bend if it wants to crack.

Now with short towers 30' or less we usually just hook the boom cable to the side of the tower so 2/5 of the weight is above the hook and 3/5 below. Tighten the cable, remove bolts, careful when tower is raised up over the anchors it will kick sideways. Hold on to it and as the tower is lowered walk backwards and lay tower down.

Dave,

Thanks for the advice and wisdom. This will help me in the future big time. I like your idea of using the truck to pull off the head when lowered level with the truck bed. That seems simple enough.

Would you use the same method if lowering a 33-35 ft tower with a B602 on top? Or would you remove the head first since it's heavier? The angle iron legs are 2 3/4 inches wide. (see pics) Thank you.

Jerry

Don't try to lower an Aermotor 14' windmill on a 40' tower like that. It will turn upside down. I know. And no one had a camera.

Bryon wrote: Tue Apr 02, 2019 10:45 am Don't try to lower an Aermotor 14' windmill on a 40' tower like that. It will turn upside down. I know. And no one had a camera.

ouch, that had to hurt!

Your tower legs digging in was from either tower not being balanced well enough or not turning the tower 1/4 turn after picking up to lower or both of these. I always swing mill and tower together and dont do anything to reinforce the legs. This is the procedure with pump hoist rig or crane. When lowering you dont have the advantage of picking up the tower & head in a horizontal position to know it is balanced. So use the charts for head and tower weight from Aermotor catalog to get a total weight. Tower weight per foot is mostly linear even though you have more girt weight at the bottom. Take your total tower & mill weight, divide by 2, divide this by tower weight per foot and this gives you how many feet up to your balance point. Then you go to the next girt up to attach as this will keep you slightly bottom heavy. The motor is half the weight of a complete head

For lowering the basics on rig position: truck facing in to the wind and backed in square and centered to the tower about 2' away. Use you outriggers to center the boom on the tower. You hook to the tower on the two legs facing the truck. After you are unbolted and picked up enough to swing the tower bottom to lower, this is when you do the 1/4 turn. You can turn either way depending on which way you want the head to be. The tower when down will be perpendicular to the truck direction with the balance point straight back from the truck. With a pump hoist rig, you roll back the mast before lowering to have the mill and tower come down out of the way of the anchors.

The simple steps to lower:
Attach and pick up 3"
1/4 turn and roll back boom
Walk tower bottom out perpendicular to truck as you lower the line straight down

The simple steps to raise:
Tower & head balance point centered on opposite side of anchors from the truck
Roll back boom so you are picking straight up
Walk bottom of tower in while raising
Once raised do 1/4 turn to have grab point facing truck
Roll boom in to bring tower to anchors

Grab points on mill & tower combo
8x27 platform
8x33 highest girt
8x53 girt at 33'
10x27 platform
10x33 highest girt

I raise & lower myself with a remote and dont reinforce because there is no stress on the tower. I will say that taller towers are more of a pain because the tower when it is vertical and picked off the anchors, it wants to hang off center. I use stakes and ropes to pull the tower bottom to hold while attaching anchors.

You can see what I mean about the taller towers wanting to hang crooked by this pic of 8x53 just set
So when picking a tower up your grab point is the side facing up

Dave & Ron,

I lowered a mill today and I used both of ur advice and techniques. It was so much easier today then the last tower I lowered. Thanks for everything. I like cutting the front angle and using it as a hinge.

Jerry