# Hydralic force needed to rasie 80' mono tower?

## Main Question or Discussion Point

Hello,
I have an aplication that I need some adivice on.
I am building a 80' wind turbine and tower that I plan to raise and lower with a hydralic cylinder. The Tower is 36" .468 wall pipe for 40' then necks down to 24" .375" wall pipe for 40 foot my calculations with the wind turbine says it should weigh about 15,000 lbs with a 4000 lb turbine on it. I am giving myself plenty of room here to upgrade to a bigger turbine.

I am planning on building a hinge at the base and then go up some distance and mount one end of the cylinder to the turbine, The other end will be atatched to the concrete foundation.

1. 136" stroke, 11" bore, 7" rod not sure on the PSI but with 3K it would be good for 285 Klbs
2. 66" stroke, 7.125 bore, 5" rod, shoud be good for 120K lbs

Where woud the atatchment point have to be?

I would rather over engineer this than have a failure.
Is there anyone that has some advice on this?
Thanks

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nvn
Homework Helper
wyo123: Instead of using a hydraulic cylinder, how about if you use the method shown in the attached file? Not to scale. First raise small pole E. Tie the two ropes or cables B and C to tree trunk A. Pull rope B perpendicularly using rope D, then tighten rope C at A. Now pull rope C perpendicularly using rope D, then tighten rope B at A. Repeat until you raise medium pole F. Now repeat the same process using ropes J until you raise monopole G and wind turbine I. Diagram is not to scale.

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NVN,
I have thought about use a gin pole to raise the tower but I didnt think it would be feasable on a scale this size. My main problem was trying to raise the gin pole. I never thougth of useing a smaller gin pole to raise the larger pole. I would use a winch truck with block and tackles (there is not many trees here) So onece you get the large gin pole raised, You would then re-rig on to the large pole?
Thanks

AlephZero
Homework Helper
A pole (or two) would be more practical than the cylinder idea.

To keep the numbers simple, suppose the center of gravity of your tower + turbine is 60ft from the ground and the total mass is 20klb

Your 285klb cylinder has a stroke of 11.3 ft. If it was at an angle of 45 degrees when the tower was vertical, that would be a distance of 11.3 / 1.414 = 8 ft from the base of the tower.
So the load to start the lift woud be 20 x 60/8 = 150klb. The cylinder could provide that, but you would have an upwards force of 150 - 20 = 130klb pulling up on the hinge at the base of the tower. That is much bigger than the weight of the tower once after it is erected so you would need a much stronger hinge and base. The base would have to take the 150klb down load from the cylinder as well.

You can't make those loads smaller by moving the cylinder further out from the base without a longer stroke cylinder.

If you raise the tower by a rope attached to the top, the loads in the hinge will be much smaller because the unequal arms of the "lever" are working for you rather than against you. If you lifted vertically from at the top of the tower, the lifting load would only be 20 x 60/80 = 15klb (less than the tower weight), and the remaining 5klb would come from the downward force at the hinge. 5klb is much less than the down force when the tower is vertical, so that is not an issue.

I agree, I was trying to get away from the guy wires, But it is not really that big of a deal.
I also wanted some way of raising lower for maintenece, Without spending 1,000's on a crane. Does anyone know the best way I would go about using the gin poles?
I think you want the pole to be about 1/3 of the lenght and then just conect with cables in about three places?
Thanks

I have picked up two objects with the jin pole method. One was a 50 foot log and the other was a windmill. the toughest part of raising either was the first couple of feet. the jin pole helps get a upward force on the thing you are raising.

nvn
Homework Helper
wyo123: For the monotower mentioned in post 1, just to give you a rough idea, if you use a steel round tube for the medium-sized (second) gin pole, having an OD 184.2 mm, wall thickness 4.763 mm, and length 12.2 m, and attach the cable at the monotower at 21.5 m from the hinge at the monotower base, then you would need four strands of 14.29 mm diameter stranded steel cable (looping on pulleys) from the top of the medium gin pole to the monotower. If you need to use smaller-diameter cable, then you would need six strands of 11.11 mm stranded steel cable (looping on pulleys).

If the winch truck is 36 m away, you would need four strands of 14.29 mm cable (looping on pulleys) from the top of the medium gin pole to the winch truck. Or six strands of 11.11 mm cable. The total tensile force at the winch truck would be 80.5 kN, at 17.8 deg above the horizontal. If using four strands of 14.29 mm cable, then the tensile force required from the winch would be 20.1 kN (not including friction).
I was trying to get away from the guy wires.
I see what you mean. I seem to recall, most monotowers do not seem to have guy wires. I wonder if you could have a remote release pin that detaches your cables after the tower is erected? Some wind turbines have a winch in the turbine housing that hoists you up in a body harness, for maintenance. I see one monotower here with a hydraulic cylinder, although the picture is slightly fuzzy.

nvn