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Hi guys! Through an exchange of mails, roller bearings manufacturers have confirmed that the "nonlinearity" could come from the bearings. This rigidity depends on the type of bearing, size and clearance / preload. [thumbsup2] I have to talk with them by telephone. I'll let you know. Best Regards

Hi guys! Some doubts: [ponder] 1. What's AWOL? 2. What's FTF? I do not understand what it gives you the information ratio between the resonant frequency and the running speed frequency. Best Regards,

Pulse system is a good equipment but it's very expensive. The B&K system is the best option for Sound measurement. In the Vibration area, LMS is probably the best option with its Test Lab software (Experimental Modal Analysis). Both systems are good in that areas; B&K is danish & LMS is...

Hi guys! What is AWOL? I don't understand this word. In the beginning I think so. But after some measurements (15% of measured machines)and after check it with a hand analizer, I think the measurements are fine. The channels (accelerometers) weren't overload. The measurements are made with...

Hi Guys, I have get the full information in pdf with very good graphics of this testing. There is no more information. This one is from another machine. The horizontal line appears in vertical and axial direction. For its application, the vibration level is high. Best...

Hi guys! The 2nd attachment is not related to the first one. This is of another machine of the same type. The testing was the same: Run Down. I am sure that the problem comes from the bearing zone. I don't know if there is some looseness, the size of ball bearings, maybe the Non Drive End that...

Hi guys! I am thinking about this problem [ponder] [ponder]. I would like to know your opinion about the next one: Is it possible that a difference among diameters of inner balls of ball bearings produces this nonlinear stiffness showed as horizontal line? In negative case, how could you see...

Hi guys! Sorry about the bad quality of colour map. In this one: x-> Hz y-> rpm colour scale-> vibration level In the 2D graphic: x-> rpm y->Vibration Level In some cases, the vibration level is important and the machines should be rejected. The natural frequency is 30% far from nominal speed...

Hi Steve, At that speed the noise is normal. There is no impact noises. The orders are the diagonal lines that you can see in the colour map. The horizontal line isn't a order. I don't know what it's... Personally, I think some non linearity (but wich?? maybe the ball bearings??) is producing...

Hi guys! A new phenomenon has been seen in a Run Down of an electric generator. It is shown in the attached graphic. The machine has ball bearings with grease in two sides. One side is fixed and another one is non fixed in axial direction. The horizontal line is appeared only in 15% of...