Hi Guys,
i haven't been on for a while as i haven't needed your help, but now i could do with it.
I am having trouble diagnosing what looks like a case of misalignment or unbalance. I am getting a high running speed frequency at the drive end of a motor.The motor in question sits above the pump and is belt driven. I flagged this pump as i thought it could do with a bit of realignment. Some work was carried out, the motor and pump had new bearings fitted plus new belts ( a bit of an overhaul ). The readings were still very high at the drive end of the motor so they had the company come in and lazer align the pump and motor. More readings were taken and they were higher still. I then suspected a bent shaft so i went in armed with a dial test indicator. No problems with the shaft or pulleys they were all within about 3 thou.
Could there be an imbalance inside the motor giving this high reading at running speed.
Any thoughts would be welcomed.
I have included a spectrum in word format and those of you with Rockwell Oddessy software i have included a template.
Please help!!
Cheers

Perry Pearmain
PDM Technician
PME Ltd
12-14 Lombard Road
Battersea
SW11 3AY
02072286400
Mob 07714682768
Email - ppearmain@pme.co.uk

Condense_Pump_P12.tph (409 Kb, 45 downloads) Template

TPH is not a very common format is it. My computer does not have anything to open the file with. Sorry.

Hi Ralph,
i have attached this spectrum in word format.
Cheers

Motor_DE.doc (39 Kb, 50 downloads)

Perry,
Perform a bump test on the motor. Most probably you have a natural frequency in the motor support near running speed. Also, 0.003" runout is not good. Imagine a shaft with a 0.003" bend. You probably would flag it as well. If you find the resonance, that is the major cause. The forcing function would be residual unbalance and sheave runout.
Ron

Perry,
It looks like 1500 rpm motor and 3 thou of TIR should not be a big influance. Did this increase happened suddenly? Maybe your cooling fan lost a blade?

Perry,
What happens to the readings without the belts attached? If the vibes are still there, motor or pulley is unbalanced. If the vibes go away check the pulley groves. They could be wider on one side than the other.
Good Luck,
Jim