Slewing is the most frequent action in the working process of excavator, which has a significant impact on the loading efficiency, energy saving and handling of excavator. Different from small and medium-sized excavators, the weight and moment of inertia of super large hydraulic excavators are huge. The center of gravity and moment of inertia of the upper part will change greatly during the movement of the upper part. Therefore, the rotary system of super large hydraulic excavators has the characteristics of time-varying super large inertia. Different from the general large inertia slewing system, the slewing system of excavator requires frequent rapid start acceleration and rapid braking deceleration to ensure the loading efficiency. In the process of fast starting and braking, the large inertia has the following effects on the hydraulic rotary system
1. During the starting and braking stage, the pressure impact is large, which endangers the service life of components and system.
2. The pressure impact caused a lot of high pressure overflow, the system calorific value is large, and the system efficiency is low.
3. When braking, the inertia energy is large and the release process can not be controlled, which often causes the motor overspeed and endangers the safety of the system, and the inertia energy is difficult to be recycled.
