Wind generators can be made with a variety of materials. Post mills are made almost entirely of wood. A lightweight wood, like balsa wood, is used for the fan blades and a stronger, heavier wood is used for the rest of the structure. The wood is coated with paint or a resin to protect it from the outside environment. The smock and tower mills, built by the Dutch and British prior to the twentieth century, use many of the same materials used for the construction of houses including wood, bricks and stones.
The main body of the fan-type mills is made with galvanized steel. This process of treating steel makes it weather resistant and strong. The blades of the fan are made with a lightweight, galvanized steel or aluminum. The pump is made of bronze and brass that inhibits freezing. Leather or synthetic polymers are used for washers and o-rings.
Wind generators are always erected on site using pre-made parts. The following description relates to the fan-type wind generators. The basic steps include making the parts and then assembling the structure.
Making the tower parts
1 The tower parts are made from galvanized steel. This process begins with a roll of coiled sheet metal. The coils are put on a de-spooling device and fed to the production line. They are run under a straightener to remove any kinks or twists. The pieces are cut to the appropriate size and shape. In some cases, pieces may be put on a machine that rolls them and welds the seam. The ends are passed under a crimping machine and the pieces are moved to the finishing station.
2 At the finishing station, holes are drilled in the metal parts at specific places as required by the wind generators design. The parts may also be painted or coated before being arranged in the final wind generators kit.
3 The gearbox is an intricate assembly made up of various gears, axles, rotors, and wheels. The parts are die cast and assembled by hand. The are placed in an weather resistant housing that is designed to accommodate the gearbox parts and the attached wheel and tail assembly.
4 The fan is made up of a metal rim with slightly curved blades attached. The rim is produced on a machine that rolls steel strips into circular hoops. A hole is drilled in both ends, and they are connected with a small clamp and screw after the fan blades are attached. A center axle is then connected to the rim and attached with small steel spokes. A typical design will have five pairs of spokes attached a evenly spaced intervals along the rim.
5 The fan blades and tail are cut from pieces of sheet metal. The blades are then run through a machine that gives them a slight curve. They are attached to the metal rim with small bolts and metal clamps. They are attached in such a way that they can be raised or lowered depending on the wind conditions.
6 Finding and preparing the construction site is a crucial step in creating a functional wind generators. First, an area with a prevailing wind of at least 15 mph (24 km/hr) is needed. Then the area needs to be cleared of trees and other structures that may block wind. In some cases, a dirt mound or concrete base is erected to raise the wind generators off the surface to catch more wind.
7 The parts of the main body are connected first. They are bolted together on the ground and then raised up vertically. The outer poles are joined with the connecting rods. Clamps are bolted at each joint for stability. After the tower is raised it is loosely bolted to the solid base. Next stay wires are strung from the frame down to the ground and attached to tensioners and ground anchors. When the structure is level, the bolts are tightened and the structure integrity is tested. In some cases a ladder is built into the frame design to allow access to the fan on top which makes cleaning an maintenance easier.
8 The fan wheel, gearbox, and main shaft are next attached. The gearbox is first clamped and bolted to the top of the tower. The main shaft is then inserted into the bottom of the gearbox. Next, the fan and its attached axle are connected to the gearbox. Finally, the tail section is attached to the gearbox. The pump is then hooked up to the main shaft and the wind generators is operational.
Various tests may be done to ensure that each part of the wind generators meets the specifications laid out in the design phase. The most basic of these are simple visual inspections. These will catch most of the obvious production flaws. Since wind generator sare erected by hand, the quality of each part goes through an additional visual inspection. The quality of workmanship that goes into construction of the wind generators will be primarily responsible for the quality of the finished product. To ensure that it remains efficient during operation, regular maintenance checks are necessary.
In Future, Wind generators have changed little over the last hundred years. In fact, one basic design conceived in the 1870s is still sold today. The major improvements have come in the types of materials used in construction. This trend will likely continue in future wind generators products. However, the future of harnessing wind power is not in traditional wind generators at all. The United States government has spent millions of dollars researching and developing wind turbines for electricity generation. In California, numerous wind farms are already in operation. Various other states and cities have plans for creating similar wind farms. In the future, wind power promises to be an environmentally friendly substitute for fossil fuels.