a, stem of the grapnel containing core; b, flukes; c, recess for
insulated contact-plate connected to core; d, covering plate screwed on
bottom of grapnel; e, button of plug; f, rubber washer and button; g,
metal-plate; h, stem of plug, on which in the under counter-sink, U is
a small metal disk which prevents the fittings from fallings out; i,
needle; j, spring; k, counter-sink for head of plug; l, counter-sink for
spring.
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