Prepared by: PANEL OF NOISE AND VIBRATION

Signature:

Name: DR. NOORMAZIAH BTE JAFFERI

Date: 01 JULY 2009

Approved by: HEAD OF ENG. MECHANICS DEPARTME

Signature:

Name: DR. HJ. BADRUL BIN OMAR

Date: 01 JULY 2009

Document Reference No. NV-LS-05 Page Number 1 of 7

Edition 1

Revision No. 2

Amendment Date 1 JULY 2009

Document Title

LABORATORY

PRACTICUM

BDC 4013 Effective Date 6 JULY 2009

COURSE INFORMATION

COURSE CODE : BDC 4013

COURSE NAME : NOISE AND VIBRATION

EXPERIMENT : GEAR MESH AND BELT SPECTRUM

1. INTRODUCTION

Successful diagnostics and troubleshooting of rotating machinery require an accurate and

repeatable quality data collection. The understanding of machinery design and operating

dynamics is vital to accurately interpret typical fault pattern and symptoms.

There are various problems with gear meshing and belt drive. These include part worn, loose,

mismatch and eccentricity.

The defect can be highlighted through frequency patterns resulted from data measurement.

Normally the defect can be identified by high amplitudes at timing frequency

2. OBJECTIVES

The objective of this experiment is to determine the gear mesh and belt frequency in rotating

machine.

3. LEARNING OUTCOMES

At the end of this experiment, the student would be able to

a. Differentiate the vibration characteristics of belt and gear mesh,

b. Obtain the resonance frequency of gear mesh and belt

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Revision No. 2

Amendment Date 1 JULY 2009

Document Title

LABORATORY

PRACTICUM

BDC 4013 Effective Date 6 JULY 2009

4. THEORY

Normal Gear Spectrum

A normal spectrum shows 1x and 2x RPM. Along with gear mesh frequency (Fg). Fg commonly

will have running speed sidebands. All peaks are of low amplitude. A typical pattern is shown in

Figure 1.

Worn, Loose and Mismatched Belts Spectrum.

Belt frequencies are below the RPM of either the motor or the driven machine. When they are

worn, loose or mismatched, they normally induce 3 to 4 multiples of belt pass frequency (F x PI x

D/L), 2 x belt frequencies is often the predominant peak. A typical pattern of loose belt is depicted

in Figure 2.

Figure 1: Gear Mesh pattern Figure 2: Belt pattern

5. APPARATUS

A specific experimental test bench and portable measurement tool (vibration analyser) with

accelerometer is used for this experiment.

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Revision No. 2

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Document Title

LABORATORY

PRACTICUM

BDC 4013 Effective Date 6 JULY 2009

6. PROCEDURES

Part A: Gear Mesh.

1. Mount accelerometer in correct position.

2. Set the frequency converter to 50Hz and switch on the motor.

3. Take readings according the route content: measurement points 3, 4, 5 and 6.

4. Set up the portable measurement tool (vibration analyser).

5. Print the relevant spectrum for each measurement point.

Part B: Belt

1. Mount accelerometer in correct position.

2. Set the frequency converter to 50Hz and switch on the motor.

3. Take readings according the route content: measurement points 7 and 8.

4. Set up the portable measurement tool (vibration analyser).

5. Print the relevant spectrum for each measurement point.

Document Reference No. NV-LS-05 Page Number 4 of 7

Edition 1

Revision No. 2

Amendment Date 1 JULY 2009

Document Title

LABORATORY

PRACTICUM

BDC 4013 Effective Date 6 JULY 2009

7. OBSERVATIONS

Observe the experimental measurement by completing Table 1 and Table 2. Take note on the

measurement reports and issued spectra, the presence of the gear mesh and belt frequency.

Table 1: Data measurement for gear mesh

Accelerometer Spectrum Velocity

(RPM)

Frequency

(Hz)

Amplitude

(g)

p3

p4 Point 3

p5

p3

p4 Point 4

p5

p3

p4 Point 5

p5

p3

p4 Point 6

p5

Table 2: Data measurement for belt

Accelerometer Spectrum Velocity

(RPM)

Frequency

(Hz)

Amplitude

(g)

p3 Point 7

p4

p3 Point 8

p4

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Amendment Date 1 JULY 2009

Document Title

LABORATORY

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BDC 4013 Effective Date 6 JULY 2009

8. DISCUSSIONS

1. Explain the characteristics of vibration occur in gear mesh and belt frequency.

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2. Compare the result obtained at p3, p4 and p5 of gear mesh frequency. Explain.

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3. Compare the result obtained at p3 and p4 of belt frequency. Explain.

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4. If, the gear tooth is wear, what do you expect the characteristics of the spectrum?

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5. If, the belt resonance, what do you expect the characteristics of the spectrum?

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6. If you want to use either one of this part, which part will you use? Please explain why?

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Document Title

LABORATORY

PRACTICUM

BDC 4013 Effective Date 6 JULY 2009

9. CONCLUSION

Please comment on your experimental work in terms of achievement, problems facing throughout

the experiment and recommendation for improvements.

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10. REFERENCES

1. Rao, S. S., (2005). “Mechanical Vibrations”, 4th Edition, Upper Saddle River, NJ: Pearson

Education

2. De Silva, C. W., (2000).”Vibration: Fundamentals and Practice,” 2nd Edition, Boca Raton, FL:

Taylor & Francis.

3. Ver, I. L. and L. L. Beranek (2006).”Noise and Vibration Control Engineering: Principles and

Applications”, 2nd Edition, New Jersey: John Wiley.