Otis the Tractor

This is one of the sweetest books ever. Otis is a gentle, fun-spirited tractor who enjoys life on the farm. His best friend is the calf who sleeps in the stall next to his in the barn. They spend their days working and playing and sitting under the apple tree. Then the big yellow tractor shows up and Otis is displaced.
The story deals with learning we still have value and can impact the lives of others long after we think we have become obsolete. It's about friendship. And it's about the putt puff puttedy chuff that saves the day.