1984 >> August >> Porcelain Insulator News  

Porcelain Insulator News
by Elton Gish, NIA #41

Reprinted from "INSULATORS - Crown Jewels of the Wire", August 1984, page 24

The Imperial bushing pictured below was first reported in this column April, 1981 on page 22. It is 12" long and is incuse marked on the wide center ring: IMPERIAL 116597

There is a second Imperial bushing known (pictured 2nd) that is much smaller. It is 5-5/8" long and has an incuse marking below the wide central ring: IMPERIAL 38922

Little is known about Imperial history. We only know about their pin types because of the many styles that exist with Imperial markings. Specimen evidence indicates that Imperial got out of the pin types about 1904, as the latest known date is 3-17-04. This date was found on a brown sim U-710. They could have likewise stopped production at that time of other HV types such as these bushings. The company continued to make porcelain items, including wiring insulators for many years until about the time of the depression. We never have been able to get any direct info (catalogs, etc.) on Imperial, only material indirectly from other sources, other jobber catalogs, etc. The door is wide open to anyone with the time to go to Trenton, New Jersey, to research old city directories, etc., to learn more about this early company.

Several years ago, Ray Klingensmith sent me this copy of a page from a C. S. Knowles catalog. Knowles was a jobber of Imperial pin types. The illustration is of a U-376A Etheridge insulator and pin assembly made by Imperial Porcelain.


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Imperial Porcelain
Etheridge Insulator and Pin

This combination is to cheapen and make reliable the corners and anchorages in transmission lines of all kinds. The pin will not bond or break.

Double or triple cross-arms or buck-arms are avoided, with much saving in initial cost and expense of erection and no expense of repair.

The insulator turns easily on pin. Acting as a sheave when drawing up wire.

The pin and insulator are made in several sizes for high voltage, cable, and electric-light work.

The tubular pin is made of the very best material. japanned. 1-1/2" inches diameter, to fit standard cross-arms. and the spring of fine spring steel. The Insulators are porcelain.

No. 1090. Insulator and pin complete. Code word. Ether. For 15,000 volts or less.; groove. 1 inch diameter.

No. 1091. Insulator and pin complete. Code word, Ethique. Heavy for cable work: groove, 1-1/2" inches diameter. 

The next photo is of two U-3's with Fred Locke markings 0-5 AN6 6-3. These are underglaze markings in green ink. Underglaze markings on Fred Locke Pony insulators are very rare, if not unique. These were first cataloged by Locke in 1899 as the No. 6 Pony. The No. 6 Pony was changed to U-38 in 1902. Locke catalogs have not been found for 1903-1906, but Ohio-Brass was a selling agent of "Victor" insulators and listed the U-3 in their 1905 catalog as the "Victor" Pony No. 9. It was listed as such in Locke catalogs for many years after that.

The photo is also a good example of the many variations found in Fred Locke insulators of the same U-#. The position, shape and depth of the wire groove added by green trimming is not a constant. The overall insulator body is pressed in a hollow cavity (no groove) and, after the damp insulator has been "cured" a day, it is mounted on a spindle operated by a foot-switch and spun, the side groove being trimmed in with a cutter swung over against the spinning insulator. For something as simple as the U-3, the whole trimming cycle for the operator would be less than five seconds -- about ten or more trimmed per minute. Groove height would depend on how the insulator seated on the spindle, how the trimmer was set up, how sloppy the arm was hinged, etc. Depth is controlled only by operator eye in that split second it takes to do it. Groove shape is just how the trimmer blade was shaped. They look like pieces of scrap "tin", but are probably made of something better that will take a temper as old hacksaw blades or any type of spring steel strip. Thus, unless obviously meant to be different in a gross way, we can't consider these variations as different "styles" and assign them different U-#'s.



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