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Think First, Then Troubleshoot — Chapter 4: Fault, Cause & Remedy

July 25, 2013

Richard J. Mitchell wrote a series of 12 articles describing a systematic approach to diagnosing malfunctions in hydraulic systems. Hydraulics & Pneumatics published this series in every other issue beginning in February 1989 and ending in December 1990. Here is Chapter 4: Fault, Cause, Remedy.

Alan Hitchcox Blog

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Figure 4 — System fault analysis. (Click image for larger view.)

Noise, heat, vibration, and leakage can interfere with the proper operation of a hydraulic system or provide warning of future problems. Maintenance and troubleshooting personnel can help avoid these problems — simply by using their natural senses of sight, touch, and hearing in an organized pattern.

As previously mentioned, a hydraulic system may malfunction or operate improperly because of one or more problems located away from the system. One example would be cavitation or aeration in a pump located in a remote pump house. Under such conditions it might help to use the Fault, Cause, Remedy (FCR) review process outlined in Figure 4.

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Figure 5 – Pinpointing excessive noise. (Click image for larger view.)

Seldom is an entire system at fault even though several malfunctions may occur in close sequence. In a large system, first examine that part of the hydraulic installation where the faulty component is mounted. Follow these steps:

1. Determine which of the four basic problem symptoms seems to apply: excessive heat, noise, vibration, or leakage. If the problem is heat, see Figure 4. Vibration and leakage investigation will be covered in Chapter 5.

2. If excessive noise appears to be the problem, consult the chart in Figure 5. It provides a selection process that considers many common conditions associated with excessive pump noise.

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Figure 6 – Pump cavitation causes and remedies. (Click on image for larger view.)

3. If, after this examination, you conclude that noise is caused by pump cavitation or aeration of fluid, check the system following the suggested Fault-Cause-Remedy sequences shown in Figure 6.

About the Author

Alan Hitchcox Blog | Editor in Chief

Alan joined Hydraulics & Pneumatics in 1987 with experience as a technical magazine editor and in industrial sales. He graduated with a BS in engineering technology from Franklin University and has also worked as a mechanic and service coordinator. He has taken technical courses in fluid power and electronic and digital control at the Milwaukee School of Engineering and the University of Wisconsin and has served on numerous industry committees.