The Humber was a rectangular chassis frame with a rear mounted engine. The gearbox was mounted to the front of the engine; it fed a centrally mounted transfer box which distributed power to front and rear differentials. The rigid axles were mounted on leaf springs front and rear with hydraulic dampers. The welded armoured hull was mounted at four points - front, rear and sides - to give some flexibility but with precautions against excessive movement of the hull on the chassis.