150 mm sIG (schweres Infanterie Geschütz) 33: German heavy infantry gun
Sources differ on the development history, but the gun itself was of conventional design. Early production models were horse-drawn, with wooden wheels. Later production models had pressed steel wheels, with solid rubber tires and air brakes for motor towing, albeit at a low speed (only carriages with pneumatic tires and suspension system could be towed at highway speeds). As with most German artillery carriages, the solid rubber tires and lack of springing meant that the gun could not safely be towed above 10 mph, and horse-drawing was still extensively employed.
