Tarou-san no Kisha

These 2 short monochrome movies feature Trains as the main focus, albeit separated by a few decades and differing animation styles. 

Both are short and old anime that teaches about manners and has moral lesson. Tarou-san no Kisha is more action 

The main characters of both films (young boys) have an immense fascination with trains. After they both happen to receive a toy train set as a present when a close relative comes back after a trip, the two both dreamed of fantastical tales of their adventures on their imaginary train. Needless to say, both male protagonists cherish their gift and their love for trains is an important theme in both these movies.