It's a bit late to "beg to differ", but I think 22d has nothing to do with electric motors: it's just 1 wd mng bushes split into 1+ 4 letters, the first being an abb for the colour & the 2nd a kind of plant---but I may always be wrong...............
Hi GK
You may well be correct - I may have "over-complicated". I wasn't happy about the definition in your interpretation (my first thought), but I suppose it is OK.