Page 10 - 810 Trianing Book Extract

B Machine basics: how to understand machine types

for vibration testing

Electric motors (ac/dc)
Consistent machine conditions—VFD is OK
Hundreds in a typical plant

Turbines
Not good—rapid speed changes and many Very few in a typical plant
s
variables
nt
e
Reciprocating engines
Not good—very large noise and many variables
Very few in a typical plant
em
l
Stepping/hydraulic
Not good—rapid speed changes and many Very few in a typical plant
g e
variables, low RPM
n
vi
Note 1: Motor shaft limit: 200 - 12,000 RPM (limit does not apply to driven component or power transfer unit
ri
output shaft)
D
Note 2: Gray area. Not all complex machines are bad and not all simple machines are good (rapid/excessive variation)

Direct drive
Consistent machine conditions—close-coupled
Hundreds in a typical plant

Couplings
Consistent machine conditions—lex and rigid
Hundreds in a typical plant

Belt/Chain Drives
Consistent machine conditions—all types
Hundreds in a typical plant
Gearboxes
Consistent machine conditions—1, 2, 3 stages
Many in a typical plant
er
Exotic gearboxes (planetary)
Not good—rapid speed changes and many Very few in a typical plant
sf
variables
n
ra
Exotic couplings (luid, Not good—rapid speed changes and many Very few in a typical plant
r t
magnet)
variables
e
w
Multiple components
Not good—rapid speed changes and many Very few in a typical plant
Po
variables

Note: If the driving element and the driven component are a good it, but the power transfer is a bad it, you may be
able to diagnose them separately (i.e. standard motor and standard compressor can be diagnosed, ignore the results
from the exotic gearbox)

Pumps
Consistent machine conditions—all types
Hundreds in a typical plant

Fans
Consistent machine conditions—all types
Hundreds in a typical plant

Compressors
Consistent machine conditions—all types
Many in a typical plant
s
Blowers
Consistent machine conditions—all types
Many in a typical plant
nt
e
Other—spindle (single shaft)
Consistent machine conditions—most types
Many in a typical plant
n
po
Machine tools
Not good—very close tolerances and many Very few in a typical plant
m
variables
o
g c
Multiple shafts
Not Good—rapid speed changes and many Very few in a typical plant
n
variables
vi
ri
Note 1: If not a pump, fan, compressor, blower, then just call it a spindle (single shaft)—conveyors, mixers, mills, etc. D
(see following pages)
Note 2: Gray area. Not all complex machines are bad (2-3 simple machines) and not all simple machines are good

(see page 139)

Note:

• Consistent machine conditions during test period are good for the tester
• Rapid speed changes with many variables, or motor speeds of less than 200 or greater than 12,000 RPM are not good for

the tester

58 Section 2: Vibration tester training manual