Telegraph engineering : a manual for practicing telegraph engineers and engineering students (1922)
Hausmann, Erich, 1886- · New York : D. Van Nostrand Company · leaf 262
ted upon themselves,called shading coils. An aluminum vane, pivoted in jewelbearings, is arranged to move up and down in the air-gap.When an alternating current traverses the field coils, ashifting magnetic flux is established at the air-gap v/ith theaid of the shading coils, which flux causes an… … V7777P Fig. 17. Fig. 18 shows the appearance of the centrifugal frequencytrack relay made by the same concern and used on alter-nating-current electric railways employing the two-railblock signal system. Other types of alternating-current re-lays for both one-rail and two-rail automatic signal…
Telegraph
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