The Oshkosh S-Series compressed natural gas-front discharge concrete mixer features an 11-yd. drum with a 45-in. opening, and 8.9-liter, 320-hp engine. The rugged transfer case and proprietary axles were developed for military vehicles, and the Load Span Tag Axle features a hydraulic system with a higher weight rating than other tag axles. The ergonomic cab is optimized for visibility and easier troubleshooting. McNeilus Companies Inc.