Cavitation

When the hydraulic fluid flow increases the speed, it will create a low-pressure zone.  The gas in the fluid will form an air bubble.  And when these air bubbles pass through a high-pressure zone, these air bubbles will be partially compressed into the extremely high pressured matter and impact the surface material and cause some unusual vibration and noise.  This will erode the surface of the pump wall, which is called cavitation.  The extent of cavitation depends upon the amount of gas dissolved in the fluid, the flow rate change, and the viscosity of the fluid.  When cavitation occurs, it will drop the efficiency of the pump and decrease the output of the pump.  To prevent cavitation from happening, one could increase the intake diameter to stop the pump from sucking in air and clean up the filter to reduce any resistance and increase the suction capacity of the pump.

1. Cavitation

Reason1: Tube Diameter Too Small Or Clogged Up
Reason2: Hydraulic Fluid Containing Air Or Moisture
Reason3: Fluid Filter Clogged With Foreign Object Or Too Fine
Reason4: Viscosity Too High And Caused The Pump To Suck In Air; Viscosity Too Low And Caused Overheating Of Pump
Reason5: Improper Location Of Fluid Intake Or Lack Of Fluid

2. Wear And Tear Of Hydraulic Component

Reason1: Worn Out Or Cracked Gear
Reason2: Worn Out Shaft Or Bearing

3. Improper Installation

Reason1: Pump Shaft Does Not Line Up With Motor Shaft
Reason2: Loose Drive Shaft Union
Reason3: Loose Bolts

4. Improper Design

Reason1: Pump Components Do Not Meet The Design Standard
Reason2: Motor, Pump And Oil Reservoir Do Not Match Up Properly