dulunche: applying the leverage principle
a villager pushes a wheelbarrow in zhujiayu village, shandong province. (photo: vcg)
by bi weizi
the chinese wheelbarrow was called dulunche in the dream pool essays written by shenkuo in the northern song dynasty (960-1127). the earliest image of wheelbarrows can be found in the stone carvings of the wuliang temple in the eastern han dynasty, dating back more than 2,000 years. the wheelbarrow is a human-powered, single-wheeled cart used to carry all kinds of loads, from harvested crops to mine waste, and pottery to construction materials. wheelbarrows could also be used to transport the sick, wounded, or elderly.
the structure of a wheelbarrow consists of a wheel in the center of the body, a wooden frame plate on top, and two rear shafts mounted on the frame plate. the common feature of wheelbarrows is the single wheel, but the shape and structure of the vehicle plates are different. one type of frame plate is flat and can carry things or people; the other type has a stand in the middle of the frame plate, and both sides of the stand are used to carry things or people. between the two axles is a rope that rests on the person's shoulders to help both hands hold the axles. by using the wheel as a fulcrum, the load's point of resistance is closer to the fulcrum, which improves its own operating efficiency and can prevent the human body from directly bearing heavy pressure. when pushing a wheelbarrow, it becomes relatively easy for people to carry a load.
the wheelbarrow，which has been used by chinese for over 2000 years，is a demonstration of the ancient chinese mastery and application of the principle of leverage, sharing the load between the wheelbarrow and the person. instead of carrying heavy loads on one's back or burdening a pack animal with them, a person could place them in a tub or basket that has a wheel and long handles attached for pushing or pulling.
