The Caterpillar 637D is a self-loading wheel tractor-scraper used for earthmoving, haul, and grading applications. As part of Caterpillar's scraper lineup, the 637D is designed to cut, load, transport, and spread material in one machine, making it suitable for large-scale site preparation, road construction, and mining support work. The model typically features a twin-engine configuration, articulated steering, and a high-capacity bowl for moving soil, gravel, and other loose material. The 637D is recognized for its production-oriented design, serviceability, and use in high-volume material handling operations where efficient cycle times are required.