Complex sentence: A hydraulic system under the control of the driver could swivel the propellers; the commander stood on a platform on the turret, where he could see over the skirt, and steered the tank with a large tiller.
Split into simpler sentences: A hydraulic system under the control of the driver could swivel the propellers. The commander stood on a platform on the turret, where he could see over the skirt, and steered the tank with a large tiller.