This first volume, which includes Allis-Chalmers and Case, as well as Caterpillar from the 1920s, 1930s and 1940s, takes a long colourful look at the development of the crawler tractor and bulldozer. The crawler photographs and text are arranged chronologically so the reader can follow development of the machines through the years. Throughout the research period for this book, hundreds of black-and-white and colour photographs were taken at shows, and numerous illustrations were gathered from libraries, machinery manufacturing companies and from private collections, and this first volume includes nearly 400 of them.