- "New-fangled nonsense!"
- — Gordon referring to Rocky, Edward Strikes Out, tenth season
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 the docks before his cargo was properly secured, causing pipes to spill onto the Main Line. Edward was adamant that Harvey could 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.
In Blue Mountain Mystery, Rocky helped clear up the broken Blondin Bridge, nearly took off Skarloey's cab and lifted Thomas onto Owen's platform.
In the eighteenth season, Rocky and James attempted to help Duck get out of a flooded track, but due to James leaving before Rocky's crane arm could be secured down properly, Rocky inadvertently knocked over a signal.
In the nineteenth season, Rocky was taken to Bluff's Cove to lift a beached whale onto a flatbed bound for Brendam. He also rescued both Thomas and James. He later derailed near Ulfstead Castle and the rest of the rescue team had to learn to work together to help him.
Duck brought him to lift Thomas out of a deep cavern after the track had collapsed and he later pulled Captain Calles' Pirate Ship out too. He received credit for finding the ship even though Thomas had found it, which annoyed Thomas. Later, he rescued Thomas after he fell in the water and attended the Harwick Branch Lineopening ceremony.
Rocky likes to lift heavy objects such as engines, coaches and trucks. He is a friendly and careful crane and helps the engines when there is an accident. He takes pride in his work and is always happy to help.
Rocky is a Ransomes and Rapier 45-ton steam crane, built around 1945. A crane of this type is preserved on the Bluebell Railway
Rocky is painted brick red with yellow hazard stripes on his sides and back.