I've got an HO crane with R/C control video. To see it work got to approx. 6:30. The first part of the video are pictures of it's construction. I'm also working on a limestone quarry animation using HOn30 from loading bins, to loading cars, transporting the load to bins on the standard gauge, and then loading the standard gauge cars. Animation is easy with todays micro motors. Here's a picture of the two motors that control the small hook and boom of the Athrean crane. Note size of motors compared to the pencil.

U-tube animation video.
https://youtu.be/X-upfCtxtLY?t=386Bernd