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How to Repair a Mechanical Windmill

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According to Telosnet, the first documented windmills were invented in Persia between 500 and 900 CE for pumping water and grinding grain. Windmills appeared in Europe during the 13th century and used geared cogs to turn a grindstone for grinding grain. Windmills have been used and redesigned for over a millenium, offering a multiple variations and applications. Hence, due to the multiplicity of designs, there may be a variety of problems to troubleshoot for the windmill on your property.

Inspect the windmill during periods of extreme gusts of wind. These are the moments when the windmill will be under the most stress, and you may notice more play in the system than under normal conditions by looking at the blades, the blade hub and mechanical components such as gears and gear shafts. Note any aberrations from normal operation you observe, and make a plan to fix structural and mechanical components that need attention.

Inspect and replace any broken blades, using the same material, if available. Using different materials for newer blades can lead to imbalances in the rotation of the hub and improper functioning of the windmill. If necessary, replace all of the blades with those of similar design, length and pitch (angle at which the blades are positioned towards the wind).

Inspect and replace the blade hub if necessary. The blade hub is the central point where the combined torque from the blade system is integrated mechanically into the rest of the windmill. It is often is one of the most stressed features on a windmill. If the blade hubs use bolts and nuts to connect the blades to the rest of the windmill, you will need a tap and dye kit to install threaded holes into the new blade hub. You will also need to use a power drill or socket wrench to attach the blades to the new blade hub.

Weatherproof mechanical parts on the windmill's interior if there is a separation between the interior and exterior of the windmill. Depending on your windmill's design, weatherproofing may require adding weatherproofing wrap used around residential building exteriors, new roofing materials, caulking and flashing. Wooden windmills will occasionally require reframing some of the interior structural components such as trusses and joists.

Inspect the gearings of your windmill. If gears and cogs are rusted or have damaged teeth, then you may need to replace all of the components related to the gearing with a new gear box. At this point, you may also want to consider changing the ratio of the gears in order to either acquire more power or more speed from turning gears.

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