Helga Horse (hu) is reading the little red book (红) in the engine's kitchen ((e)ng2), when she discovers that it is being eaten by a silk worm (纟). She overreacts a little and wants to beat the silk worm with a steel beam (工).
工
=
二
+
丨
:
Mnemonic symbol: a steel beam, since 工 looks like the cross section of a steel beam. In front of the engine ((e)ng1), Gitta Giraffe (gu) is doing some hard work: She's stacking a capacitor (二) on a dinosaur bone (丨) on a capacitor (二). She's not very successful, but then she gets the idea to use steel beams (工) as support.