Fred M. locke was the first manufacturer in the world to introduce larger conventional multipart designs for the 23 to 70 kV voltage range. These were introduced between 1901 and 1904 . The biggest variety was introduced in early 1903 when no less when 14 septate designs were made available for this voltage range . When I say "conventional" I mean insulators of two or more shells socketed into one another . The early 1900 "gutter" or "Victor combination" designs, wile technically being multiparts were of a very unconventional design. The main top shell of the early gutters was actually not made as a socket to receive the lower cemented shell but rather had a flat surface on the underside with a seprate collar glazewelded to it to receive the lower skirt .
The design of the first gutter tops like the M-2795 was highly flawed as lateral sheer could easily rip the top off the insulator . Undoubtedly this mechanical failure mode was one reason the original gutter design was abandoned . The first larger mass produced conventional design Locke multipart introduced was the M-2842 in early 1901 . Two conventional designs were shown in the 1902 catalogue M-2998, M-2842a three more were brought to market later that year. ( M-2250, M-3062, M-3725)
1903 saw the near total elimination of the older " Gutter" combination designs with only the ever popular M-2332 remaining in production for two additional years . 1903 also saw the first ever four part cemented multiparts .
Pictured here are all the surviving smaller three part designs Fred Locke produced in 1903. The first three, left to right, show the rapid evolution of the #311 known as the "Hudson type" first used by the Hudson River Water Power Co in late 1902 . The center right piece is the #315 which is speculated to have been installed on a line in Peru in 1903. On the far right is the larger #331 (M-3236) which was first used by the Utah Sugar Co on a line from the Weelon powerhouse on the bear river to Ogden Utah. The larger #331 was also installed on a line along the Battle Creek interurban to Jackson Mi. and on a line in India related to the Kolar Gold Fields . The smaller #311 became one of the most popular multipart designs for the next 25 years with literally hundreds of thousands of them being made by every major porcelain manufacturer up to the early 1920's.
Many of the early cemented Fred Locke designs that have Fred Locke hand stamp markings are extremely scarce today in collections because of their very limited production time frame . Most were also only put in service on one or two lines. Do to large numbers of early field failures which were often a result of electrical puncture do to fracturing of the ceramic from cement expansion, most of these were removed from service by the mid 1920's . because of their large fragile nature very few whole examples of any of these survived to modern times . Although many thousands of these insulators were produced for the lines where they saw service, today only a single specimen to a dozen or so of each design pictured here have been found intact. Small numbers of damaged units were also found and repaired which represents toe bulk of surviving examples .
Left to right M-3062, M-3062a, (wider lower skirt then M-3062) M-3060, (wider longer centre skirt then M-3062) M-# not assigned yet, M-3236.