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Rolling Element Bearing Problems

 


Note: X = rotating frequency

ftf = fundamental train frequency (approx. = .38X to .42X)

bsf = ball spin frequency (approx. = 1.5X to 3X)

bpfi = ball pass frequency, inner race (approx. = 4X to 10X)

bpfo = ball pass frequency, outer race ( approx. = 2X to 7X)

 

Vibration Source

 

 

Exciting Frequency

 

Dominant Plane

 

Amplitude

 

Envelope Characteristics

 

Comments

 

bpfi, harmonics of bpfi

 

radial

 

steady

 

radial

 

radial

 

high, steady

 

bpfi and prominent harmonics

 

radial

 

high, steady

 

bpfo and harmonics

 

radial

 

steady

 

bpfo and harmonics

 

radial

 

steady

 

wide band

 

Broadband noise level increases

 

bsf and harmonics

 

radial

 

steady

 

narrow band

 

radial

 

high, steady

 

narrow band

 

Broadband noise level increases

Defective Inner

Race single defect , small

Non-synchronous peaks

Radial load

Defective Inner Race single defect, moderate

bpfi, with harmonics and 1X sidebands

Amplitude modulated

Non-synchronous peaks with 1X sidebands

Radial load increases levels

Defective Inner Race

two or three

defects, small

bpfi and prominent harmonics

broad band

Broadband noise level increases

Defective Inner Race multiple small defects with rough-ness around

entire race

Non-synchronous peaks

Broadband noise level increases

Defective Outer Race

single defect, small

Non-synchronous peaks

Harmonics higher in level than fundamental

Defective Outer Race single defect, moderate

Defective Ball or Roller single defective ball

 

multiple

defective

balls

bsf and harmonics





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