Complex sentence: The Diesel is due to pull a train of holidaymakers, but his air intake is clogged by the bowler hat of a maintenance inspector, and the train has to be pulled by Duck the Great Western Engine and Stepney.
Split into simpler sentences: The Diesel is due to take a train of holidaymakers, but his air intake is clogged by the bowler hat of a maintenance inspector. The train has to be taken by Duck the Great Western Engine and Stepney.