621K Wheel Tractor-Scraper Flywheel Power: Tractor/Scraper 304 kW (407 hp) Scraper Capacity: Heaped 24.0 yd3 Top Speed (Loaded) 33.5 mph View Specifications 631K Wheel Tractor-Scraper Scraper Capacity: Heaped 34 yd3 Top Speed (Loaded) 34.7 mph Width 155 in View Specifications 637K Wheel Tractor-Scraper Scraper Capacity: Heaped 34 yd3 Top Speed (Loaded) 34.7 mph Width 155 in View Specifications 657G Wheel Tractor-Scraper Flywheel Power: Tractor/Scraper 447 kW (600 hp) / 337 kW (451 hp) Scraper Capacity: Heaped 44.0 yd3 Top Speed (Loaded) 33.0 mph View Specifications