Thread:Thunderbird1InternationalRescue/@comment-25600892-20161220232617/@comment-25372003-20161227171541

The reason you can't see his wheels is because he's what's called a Shay locomotive (meaning, he's driving by gears rather than drive rods), and he's got sideplates to protect his gears from being dirty, because he fears that if his gears get dirty, they won't work properly.