Lookin' pretty good imo; clean, neat, if a bit sparse yet. I doodled out where I might take something like this cos it looked like fun. It
is a bit hard to tell without the gnarly gears and stuff that we're looking at the back of the clockface. Aside from photos of the real thing, the Boktai series has a sweet clocktower, would be good to look at if you decide to revisit it.
The limited sepia palette is cool, but some brighter reds or yellows would make for a good accent colour/focal points imo. The pipes are higher contrast/priority than the platforms; shouldn't be a problem yet, but something to keep in mind in more complicated scenes. The girders I like a lot, but maybe try some cross-braces, tanks, valves, whistles etc. for variety.
For the mechanic's legs: you could try darkening the far leg, and removing the line on the sole for better contact with the ground, and really go for a more engaged-looking pose generally by bringing the limbs away from the body for a better silhouette, and to get some nice curves in there.
