I’m monitoring a 40kW (2975rpm 2 pole) vertical lube oil pump. Please refer to the attached vibration data for the pump. On the 26th Feb the coupling (Jaw coupling) was visually inspected and found the spider completely damaged and the coupling was replaced. Based on the spectra and time waveform is there any case for concern? What could be causing the modulation at around 3.5Hz? The pump bearing was replaced on 22/11/18 and the coupling was replaced at the time as well. Is there anything in the data that could explain the coupling failure in 3 months? What would be causing the sub synchronous vibration still present after the coupling replacement on 26th Feb??
All help is much appreciated