Belt-Drive Problems
Belt/Pulley Wear, Improper Tension & Belt Resonance

Figure 1 - Typical FFT Showing Belt/Pulley Wear Problems;
Resonance Can Also Be A Problem If The Belt Resonance Coincides With
One Of The Forcing Frequencies (Driver, Driven, Belt RPMs)
Figure 2 - Belt Problems Tend To Generate 
A Large Amount Of Belt "Flap"
Belt / Pulley Wear, Belt Resonance Symptoms:
  • High radial vibration @ 2x, 3x, 4x & 5x belt rpm.
  • Excessive belt "flap" can often be seen.
  • Belts and/or pulleys will show excessive wear patterns, cracking, etc. if wear is the problem.
  • Belt tension may be a problem - belts shouldn't be too loose or too tight.
  • Belt resonant frequency can be checked by placing transducer on bearing (radially) and "twanging" the belt like a guitar string while collecting a time domain or spectrum.