failure and troubleshooting of hydraulic system

FAILURE AND TROUBLESHOOTING OF HYDRAULIC SYSTEM

1. Common Faults in Hydraulic Systems

Table 17.2 lists the most common type of defects that can be found in hydraulic systems. 

Table 17.2. Common faults in hydraulic systems

1. Reduced speed of travel of machine tool elements.

2. Slow response to control.

3. Excessive loss of system pressure.

4. Excessive leakage in the system.

5. Rise in the oil temperature.

6. Non-uniform or jerky movement of tables, carriages, etc., especially at low feed rates.

7. Increased noise in the system.

8. No supply or less supply from pump.

9. Cavitation of seal failure.

10. High rate of seal failure.

11. Poor oil life.

12. High degree of contamination level of system medium.

2. Common Causes of Hydraulic System Breakdown

Table 17.3 lists the most common causes of hydraulic system breakdown.

Table 17.3. Common causes of hydraulic system breakdown

1. Inadequate supply of oil in the reservoir.

2. Clogged or dirty oil filters.

3. Leaking seals.

4. Loose inlet lines that cause the pump to take in air.

5. Incorrect type of oil.

6. Excessive oil temperature.

7. Excessive oil pressure.

3. Fault Finding Using Troubleshooting Charts

The term troubleshooting refers to an organised and systematic study of the problem and a logical approach to the difficulty faced in a system.

Maintenance engineers often use a fault finding chart, also known as tree-branching chart, to simplify the complex fault finding process in a hydraulic circuit. A typical tree- branching chart is illustrated in Fig.17.1.

As could be seen from the chart, it asks a question which has answers only in the 'yes' or 'no' type. This answer will determine the next step to be taken. Thus, this tree-branching chart technique helps the maintenance personnel in developing a logical and rapid approach to fault diagnosis.

4. Fault Diagnosis of Hydraulic System

Table 17.4 presents the various faults, their symptoms, probable causes, and also the remedial actions that can be taken to prevent them in hydraulic systems.

Table 17.4. Various faults, possible causes and remedies of a hydraulic system and its components