Vibration Analyst Category I Equations

g = gravitational constant, 386.1 in/s2

FOR HARMONIC MOTIONS ONLY

Velocity (in/s) v = D(2πf) D = peak displacement, in f = frequency, cycles/s (CPS)

Acceleration A = V(2πf) A = acceleration, in/s2 1 g = 386.1 in/s2

FREQUENCIES

Bearing Frequencies

FTF = (Ω

2) [1 − (

B

P) cos CA] BPFI = (

N

2)Ω [1 + (

B

P) cos CA]

BPFO = (N

2)Ω [1 − (

B

P) cos CA] BSF = (

P

2B)Ω [1 − (

B

P)2

cos2 CA]

FTF = fundamental train frequency CA = contact angle

BPFI = ball pass frequency, inner race Ω = machine speed

BPFO = ball pass frequency, outer race N = number of rolling elements

BSF = ball spin frequency P = pitch diameter, in

RPM = shaft speed B = ball or roller diameter, in

SIGNAL PROCESSING

RMS peak = 1.414 rms