In order to understand and design the hydraulic system of excavator, we must first analyze the working process of hydraulic excavator and understand the operation requirements of excavator. It is necessary to master the flow, force and power requirements of each hydraulic action element, the compound action requirements of the hydraulic action element matching each other, and the flow distribution and power distribution of the oil pump when supplying oil to each hydraulic element at the same time.
The following basic actions of unload and return are explained.
1.Unload
When turning to the unloading position, the turntable brakes, adjusts the unloading radius and unloading height with the bucket rod, and unloads with the bucket cylinder. In order to adjust the unloading position, it is necessary to move the arm with the action. Unloading, mainly bucket rod and bucket composite action, between the arm action.
2.Return
At the end of unloading, the turntable rotates in reverse, and the arm cylinder and the bucket cylinder cooperate with each other to put the empty bucket to the new excavation point. This working condition is rotary, arm and bucket rod compound action. Because of the gravity effect of the arm drop, the pressure is low, the variable pump flow is large, the drop is fast, and the rotation speed is required. Therefore, the oil supply condition of this condition is that one pump has all the flow rate for rotation, the other pump has most of the oil supply arm, and a few of the oil is throttled through the bucket rod.
In order to prevent the boom from falling rapidly due to gravity, and the boom cylinder is air-absorbed, the boom can be lowered and regenerated to replenish oil.