【正文】
on exercise the gravamen steady etc. open type system fuel tank is big, oil pump from absorb the function and the shut type system, the liquid presses the pump of into pipeline directly with performance the ponent return to pipeline connect with each other, work the liquid carries on closing the circulation in the tube road of the structure tightly packed, with the air opportunity to get in touch with little, not easy infiltration system of air, so spread to move more work anization bee soon and change to depend to regulate the pump or motors to change to measure the anization realization, avoided the open type system change toward process appear of liquid press the impact and energy the shut type system more the open type system plications, because of having no fuel tank, the oil liquid spread hot and filter the condition is order to pensate the leakiness in the system, usually need a small discharge to repair the oil pump and fuel the oil a size of a function of high bar discharge not etc., will make power make use of descend in work process, so the performance ponent within the shut type system presses the motor for the liquid generally. 2) According to system the liquid presses the number of the pump, can is divided into the list pump system, double pump