Working principle of bridge crane is like a seesaw using leverage

 A lever or mechanical arm is a tool used by a bridge crane to increase its strength. The lever itself is only a simple machine, but often accompanied by a complicated rope, chain and pulley system.

 In ancient times, large temples, monuments, and fortifications were built by leverages. But some scholars argue that Egyptians are most likely to use leverage to build Pyramid.

 But in fact, most historians believe that Archimedes is the inventor of lever theory. "Give me a place to stand, I will move the earth with lever." The ancient Greek mathematician and philosopher in the third Century B.C. said.

 The lever itself is a stable rod at the pivot point or fulcrum. By forcing one side by force, some forces can be generated at the other end. The staff usually carries some articles on their bodies when lifting objects.

 There are 123 levels of leverage. A lever that resembles a seesaw or crowbar. Its fulcrum is between hard work and work force. Second types of levers, similar to trolleys, whose working force is between fulcrum  and force. Similar to tweezers in the three levers, the force between the fulcrum and the work force.

 The working principle of bridge crane is similar to that we will see pulley and hydraulic cylinder, torque is a concept of lever manipulation. The torque is equal to the force time distance or equal to the distance applied to measuring the applied force.

 Archimedes also said that the way to provide greater capability is to manipulate torque. For example, the simplest example is a simple seesaw on the playground. The center of the ten foot seesaw is directly on the pole. One child sits on the other side, one 200 pounds, another 100 pounds.

 200 pounds of children will press the seesaw to their side, and 100 pounds of children will be raised. For smaller children, 100 pounds of extra pounds must be given to 100 pounds of children to balance the seesaw.

 But if he is allowed to extend 5 feet length on the side of the seesaw. With his ten foot seesaw and his 100 pound weight, the seesaw can be balanced. If he extends his body to more than 10 feet in length, he can directly lift up 200 pounds of children.

 Cranes can lift very heavy loads because the working mode of overhead cranes is to use lever parts to manipulate torque. The farther away the distance is, the smaller the force is needed to make the elevator. In addition to playing the seesaw children, hundreds of engineers, architects and builders need to use leverage to lift huge loads every day.