Reasons for saving labor in lifting water by pulley.

Pulley is a kind of shaft, which is essentially equivalent to lever. Its fulcrum is on the axle, the resistance acts on the axle and the power acts on the wheel. The power arm is much larger than the resistance arm, so the axle is a labor-saving lever.

The pulley is a lever that can rotate continuously, and the fulcrum is on the shaft. When the axle rotates, the wheels and the axle have the same speed.

Pulley is a folk water lifting facility of Han nationality, which is popular in northern China. It consists of pulley head, bracket, well rope, bucket, etc. Shaft-based pumping lifting device in well.

Gu said, "There is a baby lying on the anchor in the well." In the Southern Dynasties and the Song Dynasty, Liu Yiqing wrote an orange and a pulley in Shi Shuo Xin Yu Pai Diao. Kwai planted in Qi Shu in Northern Wei Dynasty

Pulleys can also refer to mechanical winches. After crossing the ditch, there is a flying bridge with a width of 10 foot and a length of more than 20 feet. There are eight hoists in the customs clearance, which makes it easier to open.