No discharge

1. The pump shaft is not rotating

1) Damage to the coupling

2) Breakage of shaft or key

 Replace parts, check pressure, operating speed, and whether the shaft core extends

2. The filter mesh of the oil suction filter is clogged

·Clean the filter element or replace the filter

3. Poor air tightness or damaged seal of the piping on the oil suction side

· Replacement, tightening, or repair of the seal at the oil suction position

4. The oil suction pipe or filter is not fully inserted into the oil

·Replenish oil on the reference line of the liquid level gauge

5. The viscosity of the oil is too high

 ·Oil change, heating

6. Poor action of the blade or plunger

·Decompose and inspect whether there is any foreign matter inhaled or whether there is sintering

7. The flow adjustment of the variable displacement pump is too tight

·Increase the discharge volume, and tighten the bolt after confirming the flow rate

The pressure cannot be increased during discharge  

1. The overflow valve is malfunctioning

·Decompose the overflow valve device

2. The hydraulic circuit is under load

·Check whether the circuit is free of load, repair any malfunctions, etc

3. Leakage in the hydraulic circuit

·"It is particularly important to inspect the piping that is hot, and eliminate the causes of leakage."

4. The wear of internal parts of the oil pump affects the volumetric efficiency and reduces it

·Repair the oil pump

No discharge when pressure increases, or discharge decreases

1. The internal sealing component of the oil pump is damaged

·Repair the oil pump

2. The wear of internal parts of the oil pump affects the volumetric efficiency and reduces it

·Repair the oil pump

3. The resistance on the oil suction side is high, leading to air intrusion

·Clean the filter element and replace the filter

4. Oil seal and other components are hardened by inhaling air

 ·Replace the sealing element

loud noise

1. The resistance on the oil suction side is high, leading to air intrusion

·Clean the filter element and replace the filter

2. Air is drawn in on the oil suction side

·Repair the oil suction area

3. Air bubbles in the fuel tank

·Check the piping on the suction side or the return piping, and replace the hydraulic oil with one that has good defoaming properties

4. Wear and damage of the coupling

·Inspect the shaft core and replace the coupling

5. Wear of the moving parts of the oil pump or poor movement of the blades and plungers

 ·Repair the oil pump, inspect for any foreign objects mixed in, and replace the hydraulic oil

6. Outside the limits of speed, pressure, and regulations

·Check the number of revolutions and pressure

Pump heating

1. The wear of internal parts of the oil pump affects the volumetric efficiency and reduces it

·Repair the oil pump

2. Sintering of parts in the oil pump's fan section

  ·Repair the oil pump

No discharge

1. The pump shaft is not rotating

1) Damage to the coupling

2) Breakage of shaft or key

 Replace parts, check pressure, operating speed, and whether the shaft core extends

2. The filter mesh of the oil suction filter is clogged

·Clean the filter element or replace the filter

3. Poor air tightness or damaged seal of the piping on the oil suction side

· Replacement, tightening, or repair of the seal at the oil suction position

4. The oil suction pipe or filter is not fully inserted into the oil

·Replenish oil on the reference line of the liquid level gauge

5. The viscosity of the oil is too high

 ·Oil change, heating

6. Poor action of the blade or plunger

·Decompose and inspect whether there is any foreign matter inhaled or whether there is sintering

7. The flow adjustment of the variable displacement pump is too tight

·Increase the discharge volume, and tighten the bolt after confirming the flow rate

The pressure cannot be increased during discharge  

1. The overflow valve is malfunctioning

·Decompose the overflow valve device

2. The hydraulic circuit is under load

·Check whether the circuit is free of load, repair any malfunctions, etc

3. Leakage in the hydraulic circuit

·"It is particularly important to inspect the piping that is hot, and eliminate the causes of leakage."

4. The wear of internal parts of the oil pump affects the volumetric efficiency and reduces it

·Repair the oil pump

No discharge when pressure increases, or discharge decreases

1. The internal sealing component of the oil pump is damaged

·Repair the oil pump

2. The wear of internal parts of the oil pump affects the volumetric efficiency and reduces it

·Repair the oil pump

3. The resistance on the oil suction side is high, leading to air intrusion

·Clean the filter element and replace the filter

4. Oil seal and other components are hardened by inhaling air

 ·Replace the sealing element

loud noise

1. The resistance on the oil suction side is high, leading to air intrusion

·Clean the filter element and replace the filter

2. Air is drawn in on the oil suction side

·Repair the oil suction area

3. Air bubbles in the fuel tank

·Check the piping on the suction side or the return piping, and replace the hydraulic oil with one that has good defoaming properties

4. Wear and damage of the coupling

·Inspect the shaft core and replace the coupling

5. Wear of the moving parts of the oil pump or poor movement of the blades and plungers

 ·Repair the oil pump, inspect for any foreign objects mixed in, and replace the hydraulic oil

6. Outside the limits of speed, pressure, and regulations

·Check the number of revolutions and pressure

Pump heating

1. The wear of internal parts of the oil pump affects the volumetric efficiency and reduces it

·Repair the oil pump

2. Sintering of parts in the oil pump's fan section

  ·Repair the oil pump