FIG. 39 shows the characteristic curve of a typical gear oil pump. It can be seen from the figure that the pump power increases with the increase of pressure. It can also be seen from the figure that even under high pressure, the pump still has a high volumetric efficiency and a flat displacement characteristic curve, which is an inherent characteristic of the positive displacement pump. As long as the pump speed remains unchanged, the theoretical displacement QT remains unchanged. If the discharge pressure increases (such as turning down the discharge valve), due to the increase of the internal leakage of the pump, the actual displacement OF the pump Q decreases, so that the curve of Q tilts downward with the increase of the pressure.
FIG. 39 Performance curve of gear oil pump
