The rock crusher is a quarry machine mounted on a large well wagon.
Bill and Ben were once sent to collect it from the docks for the Anopha Quarry. When Fergus told them to be careful, the twins deliberately ignored his advice and made as much noise as they could, which only caused a landslide. Luckily, Fergus pushed them out of the way and took the force of the impact.
The rock crusher is painted in a brownish-maroon livery.