“The stepping wheel was first mentioned in chronicles in 230 BC. Until the second half of the 19th century, it remained the important element of cranes.
Such a wheel usually had a diameter of 4 to 5 meters, and had a mechanical advantage over a winch or capstan because of the larger radius of the wheel and the small radius of the axis. In addition, when working with a winch and capstan, power was generated only by a person’s arm and shoulder, which in the case of a step wheel was replaced by the force generated by a walking person or a draft animal.
The stepping wheel, thus, increased human capabilities by 14 times and made it possible for one person to lift the weight of 3.5 tons. Some port cranes were then equipped with two wheel wheels, in which 4 people moved at the same time, which made it possible to raise the weight to 14 tons. ”
Port wheel wheels were often crowned with a wooden roof to protect mechanics and workers from rain.