Could you please help me with this high vibration belt driven fan, where
high predominant 1.59 X Motor speed (2363 CPM) @ 14 mm/s, with 1X Motor speed @ 6mm/s in Horizontal (Belt tension direction) and axial DE & NDE.
Motor speed: 1485
Speed ratio: 6
Fan speed: 247.5
Motor Pulley diameter: 142.6 mm
Fan pulley diameter: 855.6 mm
Center distance: 1082 mm
Belt length: 3850mm
Calculated belt RPM = 172.72
No of blades: 6
GE (enveloping) readings are very low
These readings was taken after replacing the belt with a new one and the two pulleys were checked, but the same high vibration with same pattern have not changed.
Any suggestion for the cause of this problem, and how I can check for structural or belt resonance
New belt could have same natural frequency as old one?
Even if the natural frequency for the belt or the system be around this frequency, shouldn’t be other forcing frequency to excite this natural frequency?
How far could be the calculated RPM from the actual (Unfortunately they don't have a stroboscope or working tachometer)
If someone still using SKF single microlog, how can I perform a bump test without bump test module?