Rusty is a diesel engine who does maintenance work and odd jobs on the Skarloey Railway.
Rusty is a trusty, tame and friendly little diesel. He is a dedicated worker, often maintaining the line, while understanding and respecting the importance of his duties. He also has a rather distinctive two-tone horn. Rusty is quick to remind others with regards to proper conduct, particularly Duncan, who was initially very suspicious of the little diesel. But despite their arguments they both seem to make amends in the end, because of how kind and tolerant Rusty is. He has a good working relationship with both Skarloey and Peter Sam in particular. Caring, calm, and quick-thinking, Rusty is modestly a credit to the Skarloey Railway
Rusty is painted "rusty" orange with yellow lining and white lettering.