Excavator is an earth moving machine that uses a bucket to excavate materials that are higher or lower than the bearing surface, and loads them into a transport vehicle or discharges them to a stockyard. There are many types of hydraulic systems for excavators, which can be classified by different aspects. According to the circulation form of oil, it can be divided into open system and closed system. Open system means that the hydraulic pump sucks oil from the oil tank, the oil drives the hydraulic actuator after passing through various control valves, and the oil returns to the oil tank through the reversing valve. This article will introduce the advantages and disadvantages of the open system for reference only.
1. Advantages
1) The structure of the hydraulic system is relatively simple.
2) It can play the role of heat dissipation and impurity precipitation of the oil tank.
2. Disadvantages
1) The oil often contacts with air, which makes the air easy to penetrate into the system, resulting in unstable movement of the mechanism.
2) The diameter of oil suction pipeline is large and short.
3) The speed is limited by the suction pressure.
4) The diameter of the directional valve is determined by the system flow.
5) The size of the filter or cooler is determined by the system flow. For the system with large power, the form of separate bypass throttling filtration / cooling is adopted.
6) The system oil tank is large.
7) The installation position of the pump needs to consider its influence on the oil suction pressure.
8) The load balance is realized by the back pressure or balance valve on the oil return circuit.
