Rocky is a large breakdown crane who is part of the Sodor Rescue Team.
When Rocky was new to Sodor, Gordon and Edward were skeptical about his abilities, noting that Harvey could travel under his own power. Later, Edward carelessly left Brendam Docks before his cargo was properly secured, causing pipes to spill onto The Main Line. Edward was adamant that Harvey clear up the line, but the little crane engine was too small to finish the job quickly and as a result, Gordon crashed into the pipes. Edward returned to Brendam to pick up Rocky, who cleared the line and put Gordon back on the rails.
Since this incident, Rocky has become an invaluable asset to the railway. He is frequently called upon to lift loads and help out after accidents. He is based at the Sodor Search and Rescue Centre, but is seen at the docks and other places like Sodor Slate Quarry helping out. He also tells the other members of the search and rescue team about the calls to action.