The difference between fixed pump and variable pump

Under the conditions of constant speed, variable output flow variable pump, on the contrary for the quantitative pump. Their biggest difference is the variable pump shaft is easy to install. Simply quantitative pump speed selected, his flow and pressure is determined, it can not be adjusted. Variable pump output flow can be based on system pressure changes (external load size), automatically adjusts the flow, it is high pressure output flow is small, the pressure is low when the output flow, so he can save the number of hydraulic components, thus simplifying Oil system, but also can reduce the oil fever. The disadvantage is that the flow pulsation is serious, the system pressure is not stable, the pump life is short, the pump bearing easily broken, because he is a casual installation, and the pump noisy. Vane pump by adjusting the eccentricity, the plunger pump by adjusting the angle of the slider can achieve the variable.