As the elevator that are equipped with advanced elevator shaft parts is running, the lengths of the wire ropes on the car side and the counterweight side are constantly changing, resulting in changes in the weight of the wire ropes on both sides of the traction sheave. When the car is at the lowest floor, most of the weight of the wire rope is on the car side; when the car is at the highest floor, most of the weight of the wire rope is on the counterweight side. This change has little effect on the running performance of the elevator when the lift height is not large, but when the lift exceeds a certain height, it will seriously affect the stability of the elevator operation and endanger the safety of passengers. For this reason, when the lift height of the elevator exceeds a certain height (usually 30 meters), a component with a certain weight must be set to balance the weight change caused by the height change, which is the function of the compensation chain for elevator.