The characteristics of the gear oil pump is reliable, simple structure, easy fabrication and pump oil pressure is higher, so widely used.

When the engine is working, the camshaft drive gear on the oil pump drive gear, with motivation to make fixed on the driving gear shaft of the driving gear rotation, thus promote driven gear to rotate in the opposite direction, to pump the oil from the oil inlet cavity along the tooth gap and wall to the oil chamber. In this way, the oil cavity formation, low pressure produced by suction within the oil sump oil suction inlet chamber. Due to the main, driven gear rotating unceasingly, the oil is constantly under pressure to needed parts.