I've been doing a lot of patent searches trying to find all insulator related patents. With the internet, this has become much easier. The list now contains around 2000 patents. I thought I would share with you two patents that explain a mystery with two different insulators and a few that are very interesting. If anyone is looking for a particular insulator patent, most likely I have it in the files of the Insulator Research Service (IRS).

The first insulator was a total mystery for about 20 years. People were always asking about it and no one could ever explain what it was used for. Finally, in late 1987, someone solved the mystery. Marion Oschman wrote me to explain how it was used. It was a stand off insulator mounted on the back wall of a neon sign. The insulator held a square copper conductor in the transformer terminals with the other end securing the end of the neon tube. The four notches in the base of the insulator was where metal clips held the insulator in place. Marion even sent me one of the insulators complete with metal conductor and metal tip of the neon tube still attached.

As you can see in the next two pages from patent No. 2,173,510 (Sept. 19, 1939), the insulator can support either one or two square conductors to provide current for individual neon tubes. I believe the insulators were discontinued when neon signs were made cheaper by using one continuous tube and coating the interconnecting length of tube between the letters or numbers with an opaque paint.

The next patent deals with multipart porcelain insulators M-2322, M-3462, and M-4360 (photos page 13). These insulators have a "wire groove" at the bottom of the skirt with a notch cut out on opposite sides. It is an odd feature that no other insulator has. No one could explain it and it was not specific to one manufacturer. In fact, specimens of M-2322 have been found made by Locke and Lapp (3 of each reported and one unmarked); M-3462 made by Lapp (only 1 reported), and M-4360 made by Pittsburg HV (only 1 reported and another damaged specimen). Another interesting feature is all of the specimens known except one N-N M-2322 and the M-3462 have a cobalt blue glaze!

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Patent No. 1,574,964 (March 2,1926) covers this unique design. The patent was assigned to Electrical Engineers Equipment Co. in Chicago. You may ask how could Pittsburg HV produce an insulator that late? Notice the patent application was filed in 1918, well before Westinghouse took them over in 1921. As you can see from the patent drawing, the groove around the bottom of the skirt was intended for a metal bracket. The two notches in the bottom edge of the skirt was for a special metal bracket to fit in, which offered additional support against horizontal strain and prevented the insulator from turning. The entire design was to provide a strong insulator for heavy weight loads and horizontal strains. The only brackets I have seen were on a cobalt blue M-2322. It did not have a bracket attached to the groove at the bottom, but rather a three-legged metal base with the steel pipe pin (cemented in the insulator) threaded into the center of it. Another patent, No. 1,663,007 (March 20,1982) shows a different style top and bottom bracket. This patent is also assigned to EEECo.

In the mid-1930's, Ohio Brass was certain they could solve the problems with high voltage insulator in foggy areas. They obtained two patents for suspension insulators that are quire bizarre. You can well image the difficulty to manufacture them.

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The last patent is very odd indeed. It calls for making insulators from cow's horn. The patent is No. 1,333,188 (March 9,1920) and granted to a person in Vercelli, Italy.