盾构机由于其特有的施工工艺，动力驱动基本上都是通过液压系统进行，液压系统能否稳定运行直接关系到盾构施工的效率，根据以往施工经验，液压系统的故障有相当部分是由于液压油的不洁净引起的，因此提高液压油的清洁度等级，是保证液压系统稳定运行的关键。从提高液压油的清洁度入手，采用离心式净油机，在盾构机最关键的油箱位置，进行旁路循环净化，经过2个月的实际运行，液压油的清洁度得到了明显提高，液压系统保持稳定，液压油、滤芯消耗大幅度降低，效果显著，这项技术改造对于类似盾构机液压系统的设备改造具有借鉴意义。

Because of its special construction technique, the power drive of the shield machine is basically supported by hydraulic system, and therefore, the stable operation of the hydraulic system will directly affect the construction efficiency of the shield machine. Based on the past construction experience, the failure of the hydraulic system is caused by non-purified hydraulic oil to some extent, so the improvement of the purity level of the hydraulic oil is critical to ensure the stable operation of the hydraulic system. From the perspective of the improvement of the purity of the hydraulic oil, a centrifugal oil purifier is introduced and by-pass circulation purification is carried out at the most critical place where the oil tank of the shield machine is. After 2-month purification, remarkable effects that the hydraulic system keeps stable, and the consumption of hydraulic oil and filter element has been greatly reduced have gained, so that this technological modification can be used as a reference to the modification of equipment like the hydraulic system of the shield machine.