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The Duplex Manufacturing Company traces its origin to the Duplex Windmill Company of Brooklyn, Wisconsin in the 1880's. Even at that early date the firm was manufacturing the Duplex Vaneless windmill, although without a counterbalance weight. It was complete with its standard governing system and steel pipe wheel arms. About 1892, the firm moved to South Superior, Wisconsin, retaining its former name, but the name changed about 1895 to become the Duplex Manufacturing Company. This illustrated the efforts of the firm to diversify its product. In 1904, the company's location changed to Superior, Wisconsin, where it remained throughout its final thirty years of windmill production into the 1930's. The Duplex is a distinctive vaneless windmill with a number of obvious identifying characteristics. Prominent among these is its use of tubular steel pipe arms which are clamped and bolted to the cast iron wheel hub. At the outer ends of these arms are pivot castings which are screwed on as if they were pipe fittings. Connecting these pivot castings around the outside of the wheel are steel tie rods which according to company literature, "makes a complete cord around the frame." Also attached to the pivot castings are brace rods which extend to a casting on the windward side of the wheel spider casting, giving the wheel further stability. The main bearing surfaces of the mill initially were lubricated through open grease cups, though later mills employ compression grease cups. In addition to producing the pumping version of the Duplex Vaneless, the manufacturer from the 1880's to the 1920's, also made a power mill marketed as the Duplex Balanced Geared. These vaneless mills operate like the pumping mills with the exception that they use a system of gearing to translate the motion of the turning wheel into rotary power to operate light farm machinery and equipment at ground level. The power mills were made in 14' sizes while the pumping version was available in 10', 12', and 14' sizes. By the early 1930's, only 10' and 12' pumping mills were available. Mounting in the tower also is distinctive in the Duplex Vaneless. The weight of the main ironwork is carried in a special casting located about two feet down in the superstructure. There it is fitted with a roller bearing, while the tower cap carries an additional ball bearing. This design allows the Duplex to turn to easily face the wind, and it places much of the strain on the mill in high winds considerably farther down in the tower than the design of many other vaneless mills. Duplex Vaneless windmills were used for over 50 years throughout the Northern Great Plains and Upper Midwest. They were produced in Superior at least into the 1930's. Today the Duplex Vaneless is by no means a common windmill, but many examples both restored and unrestored, survive to be seen today. With their striking design and attractive yellow and green paint, they are one of the most appealing American Vaneless windmills. |