The World's Strongest Engine

Diesel is drafted in at the dockyard when Henry is sent away for repairs, much to the misery of the other engines. Diesel goes about determined to show how much more reliable diesel engines are then steam engines. The trucks encourage him to try pulling all of them at the same time, a challenge that he gladly expects as a way of proving himself to be The Worlds Strongest Engine. But unknown to him, the trucks brakes are hard-on, and Diesel pulls so hard that the coupling breaks, sending him through a pair of buffers and landing on a barge. Henry returns just as Diesel is sent packing, and pulls the train with ease. Thomas and Percy realize that trucks have their uses after all.