Tractor Engine is a short magazine story.
Terence chugs across the farmer's field, collecting crops in a cart. He then spots Mavis trundling along through a railway cutting below the field. Terence tells her he's working hard and is pulling a cart. Mavis tells Terence it's not the same as pulling a truck.
Later, Mavis sees Terence again. This time, Terence is pulling a plough. Mavis informs the tractor that it's still not the same as pulling a truck. As she hurries on her way, her last truck breaks free and rolls back down the line. Terence is concerned because the express is coming through soon and there might be an accident. Using his caterpillar treads to get a good grip, Terence drives down the steep slope and pulls the troublesome truck off the main line and into a siding just in time. When Mavis returns to collect the truck is thankful for Terence's actions and says he got to pull a truck after all.