It is only appropriate that a person who designs the circuits, knows what can go wrong with the power units.

In the pages to follow we are giving charts describing common problems and remedies that can solve these problems.

These charts also will be very useful for maintenance engineers using hydraulic power units in their shops.

Most of the problems in hydraulic machinery are related to oil contamination. The suction strainer can clog due to contamination. This can result in cavitation of pump. Contamination can also make the valve sticky. The DC valve coils can burn due to sticky valves.

Another point is that we should ensure oil and air do not mix. They are not made for each other.

A loose suction joint can allow system to aerate causing severe pump noise and jerky movement of actuator.

A word of Caution

We have come across problems that are not associated with power unit but are machine problems or relating to electrical circuits. Therefore it is essential that before trouble shooting, the problem is identified to be relating the hydraulics side of the machine.

CHART I-REMEDIES

1. Any or all of the following: Replace dirty filters- Wash strainers in solvent compatible with system fluid-Clean clogged inlet line- Clean reservoir breather vent- Change system fluid-Change to proper pump drive motor speed-Overhaul or replace super change pump-Fluid may be too cold.
2. Any or all of the following: Tighten leaky inlet connections-Fill reservoir to proper level (with rare exception all return lines should be below fluid level in reservoir)-Bleed air from system-Replace pump shaft seal (and shaft is worn at seal journal)
3. Align unit and check condition of seals, bearing and coupling.
4. Install pressure guage and adjust to correct pressure
5. Overhaul or replace.

Click here for : Chart I

CHART II-REMEDIES

1. Any or all of the following: Replace dirty filers-Clean clogged inlet line-Clean reservoir breather vent-Change system fluid-Change to proper pump drive motor speed-Overhaul or replace supercharge pump.
2. Any or all of the following: Tighten leaky inlet connections -Fill reservoir to proper level (with rare exception all return lines should be below fluid level in reservoir)-Bleed air from system-Replace pump shaft seal (and shaft if worn at seal journal)
3. Align unit and check condition of seals and bearings Locate and correct mechanical binding-Check for work load in excess of circuit design.
4. Install pressure guage and adjust to correct pressure (Keep at least 125 PSI difference between valve settings)
5. Overhaul replace
6. Change filters also system fluid if of improper viscosity-Fill reservoir to proper level.
7. Clean cooler and /or cooler strainer-Replace cooler control valve-Repair or replace cooler.

Click here for : Chart II

CHART III-REMEDIES

1. Any or all of the following: Replace dirty filters-Clean clogged inlet line-Clean reservoir breather vent- Fill reservoir-proper level-Overhaul or replace supercharge pump.
2. Tighten leaky connections-Bleed air from system.
3. Check for damaged pump or pump drive-replace and align coupling.
4. Check for damaged oum or pump drive-replace and align coupling.
5. Adjust
6. Overhaul or replace
7. Check position of manually operated controls-check electrical circuit on solenoid operated controls-Repair or replace pilot pressure pump
8. Reverse rotation
9. Replace with correct unit.

Click here for : Chart III

CHART IV-REMEDIES

1. Replace dirty filters and system fluid
2. Tighten leaky connections(fill reservoir proper level and bleed air from system)
3. Check gas valve for leakage-Charge to correct pressure-Overhaul if defective.
4. Adjust
5. Overhaul or replace

Click here for : Chart IV

CHART V- REMEDIES

1. Fluid may be too cold or should be changed to clean fluid of correct viscosity
2. Locate bind and repair
3. Adjust,repair, or replace
4. Clean and adjust or replace-Check condition of system fluid and filters.
5. Overhaul or replace
6. Repair command console or interconnecting wires
7. Lubricate
8. Adjust, repair, or replace counter balance valve.