Southern Pacific's Early Remote Control Locomotive Tests
Southern Pacific Historical & Technical Society's Trainline magazine Number 118 featured an illuminating article on page 26 by Ron Park, Slavery on the SP, which described his experiences with / surrounding circumstances of SP's Locotrol remote control locomotive experiments and implementation in the early 1970's.
Ron's article is great "inside" stuff, but SP actually began testing the remote concept at least as early as 1961. In may of that year, the company engaged in remote helper tests between Bakersfield and Mohave, using four unit GP9 helper sets using Westinghouse Air Brake Company remote equipment.
Another round of tests took place in August 1965, using "greatly improved" Westinghouse equipment. SD40 #7431 was the master and #7432 was the slave. This series of tests took place on segments of the T&L from Avondale to El Paso. Various combinations of locomotives were MU'ed to remote 7432, and these helper sets in-turn were tried in various locations from mid-train to immediately ahead of the caboose.
The reports by the Mechanical Department's G.M. Gaddis (title unknown) contained are only summaries of test dates and locations. Perhaps the reports about the actual test results will surface some day.
Fast forwarding to 1973, Locotrol was not the only bidder wishing to supply SP with remote equipment. The first pages of the PDF are a copy of a system offered by Radiation Incorporated, a subsidiary of Harris-Intertype Corporation, a manufacturer of printing equipment (Intertype manufactured fascinating Rube-Goldberg-like newspaper typeset composing equipment similar to the better-known Linotype machines). H-L acquired Radiation, a manufacturer of military and space communication technology, in 1967 as a way of expanding into electronic communication, a very forward-thinking move at the time. Along with the manual are sepatate purchase and installation cost estimates prepared by Gaddis, presumably for Radiation equipment. Apparently this equipment was never tested on SP.