A tilt-up tower pivots on a hinge at its base and is raised and lowered with a gin pole, a rigid arm at the hinge that gives the cable a lever arm over the mast. For a 12 m tower carrying a 50 kg turbine, a 6 m gin pole keeps the worst cable pull to about 1.8 kN at the start of the lift, while a 3 m pole raises it to 3.3 kN, so a longer gin pole and a block and tackle make the job possible for two people.
Part of Advanced Wind Turbine
A tilt-up design is a tower hinged at its foot so the whole mast and turbine can be laid down to the ground for service and raised again.
Service At Ground Level Beats Climbing
The carrier makes the tilt-up design essential for any tower over 10 meters: the tower base is a hinge, a gin pole side and a pulley system let the operator lower the turbine to horizontal, and all maintenance is done at ground level with no climbing. The Wind Power page says the same and adds that a gin pole is a short pole attached at the pivot used to get mechanical advantage at low angles; never work on the turbine at height if the tower can be lowered.
Why The Gin Pole Is Needed: A Lever-Arm Calculation
The numbers below use assumed masses: a 12 m mast of 2-inch pipe at 65 kg (5.4 kg/m, from Guyed Tower (Steel Pipe)), centered at 6 m, and a 50 kg turbine at the top.
With the tower horizontal, gravity’s moment about the hinge is:
65 × 9.81 × 6 + 50 × 9.81 × 12 = 3,826 + 5,886 = 9,712 N·m.
A cable from the tower top to the tip of a gin pole of height h standing straight up from the hinge makes a line whose distance from the hinge is the lever arm: arm = 12 × h ÷ √(12² + h²). The cable tension needed to start the lift is moment ÷ arm:
| Gin pole height | Lever arm | Cable tension | Equivalent weight | Pull with a 4:1 tackle |
|---|---|---|---|---|
| 3 m | 2.91 m | 3,337 N | 340 kg | 834 N (85 kg) |
| 6 m | 5.37 m | 1,810 N | 184 kg | 452 N (46 kg) |
| 12 m | 8.49 m | 1,145 N | 117 kg | 286 N (29 kg) |
The first-lift tension is 1.8 kN with the 6 m pole and 3.3 kN with the 3 m pole. A 4:1 tackle, four rope segments supporting the load, divides the pull by four (ignoring friction), as Pulley Systems explains. Without a gin pole, a cable from the tower top running along the ground to a winch lies nearly parallel to the mast, so its lever arm is almost nothing and the required tension is enormous. That is why the first part of the lift is the hard part, and why the cable load falls as the tower rises: the moment is proportional to the cosine of its angle from horizontal, so at 45° it is 9,712 × 0.707 = 6,867 N·m.
Layout That Keeps The Guys Working
In the usual layout the guy direction in line with the tilt is replaced by the lifting cable and its anchor. The two side guys must have their anchors on the line through the hinge axis, so their length does not change as the tower swings (a standard layout, recalled and not from the corpus); otherwise they go slack or tight during the lift. When the tower is up, the lifting cable becomes the fixed guy for that direction. The anchors themselves are in Foundation & Guy Wire Anchors.
Method: Lower The Tower
Step 1: Wait for a calm day. Do not raise or lower in wind, because the rotor and tail act as a sail.
Step 2: Lock the turbine. Apply the brake or furl the rotor and tie it so it cannot spin (Dump Load & Overspeed Protection).
Step 3: Disconnect the output cable at the base, leaving slack.
Step 4: Take up the lifting cable on the winch or tackle until it is just taut.
Step 5: Release any guy on the tilt side from its anchor (the side guys stay attached), remove the hinge lock pin, and pay out the lifting cable slowly through the winch so the tower begins to tilt.
Step 6: Lower slowly, with the ratchet pawl or brake engaged between each stage, and a helper at each side guy and one watching the tower from the side.
Step 7: Rest the turbine on a padded support at the top of the tilt, with the mast horizontal and clear of trees.
Step 8: Reverse to raise, pulling smoothly, with the side guys tensioned evenly.
Common Mistakes
- No winch brake — the tower runs away downward as the load grows.
- Side anchors off the hinge line — the guys snap taut.
- A gin pole too short — the first lift needs too much force.
Safety
A tower coming down controls its own fall only as well as the cable
If the cable parts or the winch lets go, the mast, with a turbine on top, falls through a full quarter circle in a second or two. Stand off to the side of the tilt line, never beneath the tower or in line with it. The stop is the winch pawl or brake: use a winch that cannot run backwards, and name who works it. Clear a landing strip the length of the tower before starting.
What’s Next
- Learn next: Foundation & Guy Wire Anchors for the anchors that hold the lift
- Combine with: Tower & Mounting