Common Hydraulic Failure Causes

Most often, failures start with hydraulic pumps. Studies show that 90-95% of hydraulic failures are caused by an increased rate of wear and tear on the pump due to:

  • Fluid contamination caused by foreign material in the hydraulic fluid.
  • Aeration and cavitation caused by improper design.
    • Restricted fluid flow to pump
    • Loose connection or fittings on suction line
    • Low hydraulic fluid level and/or low NPSHA
    • Excessive pump speed; be sure to check specifications of the pump and motor
    • Incorrect hydraulic fluid or wrong oil viscosity
    • Foaming oil and/or low or old oil levels
    • Clogged reservoir air breather vent
    • Too low of an oil temperature
    • Damaged or worn pump
  • Over-pressurization: subjecting a pump to pressures higher than its design specs call for.
  • Poor fluid viscosity: higher than required viscosity leads to cavitation; lower than required results in too much heat and leaks in the pump.
  • Excessive heat: heat can be either a byproduct of other failures or a trigger. It is always a warning sign that requires immediate attention.