Hawkins electrical guide ... : questions, answers & illustrations : a progressive course of study for engineers, electricians, students and those desiring to acquire a working knowledge of electricity and its applications ; a practical treatise (1914)
Hawkins, N. (Nehemiah), 1833-1928 · New York : T. Audel & Co. · leaf 298
LS 2,389 Pendulum Signals.—These are used to a limited extent inannunciator service where the ordinary gravity drop arrange-ments are subject to the liability of failing to reset. The indi-cations given by such arrangements are very satisfactory andrequire no attention as they automatically reset.… … Pig. 3,280.—Gravity drop annunciator. In operation the shutters are reset by turning theknob seen on the side of the case. a vane of fluted silver glass or a numbered card. The vane orcard swings in front of an aperture in the indicator frame.When the electromagnet is magnetized, the armature is…
Electrical engineering
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