4. Bachmann electronic GmbH
TURBINE GEARBOX COMMON INSPECTION TECHNIQUES
Component detection percentages on a typical gearbox
VISUAL INSPECTION BORESCOPE INSPECTION VIBRATION ANALYSIS
High Speed Pinion 50% 50% 100%
Intermediate Wheel & Pinion 100% n/a† 100%
Low-Speed Wheel 100% n/a† 100%
Sun Gear No 30%§ 100%
Planetary Gears (3) 10% 30%§ 100%
Ring Gear 20% 30% 100%
High Speed Bearings (3) No 100% 100%
Intermediate Bearings (2-3) No 50%‡ 100%
Low Speed Bearings (2) No 50%‡ 100%
Planetary Carrier Bearings (2) No 30%§ 100%
Planetary Gear Bearings
(6 drCRB) No 30%§ 100%
† Clearly visible during visual inspection by removal of inspection cover
‡ Depends upon gearbox make/model, oil level and bearing configuration
§ Requires several rotations of rotor and to inspect 100%, adding several hours to inspection
By Don Roberts and David Clark
5. Bachmann electronic GmbH
DIFFERENT TYPES OF VIBRATION UNITS- Velocity, acceleration,
displacement, demodulated/enveloped, time waveform, overall.
TIME WAVEFORM VIBRATION SPECTRUM
FFT
6. Bachmann electronic GmbH
CONDITION MONITORING MYTHS
. Need lots of data, lots of measurements, with a baseline
. Too difficult to understand the data
. Not cost justified
. Cannot detect planet section issues
…..All condition monitoring is the same
10. Bachmann electronic GmbH
HIGH SPEED SECTION (HSS)
secs
0 1 2 3 4 5 6 7 8
g
-0.8
-0.6
-0.4-0.4
-0.2
0
0.2
0.4
0.6
O/All 0.062 g RMS
Machine Note (3/8/2010 11:09:42 AM)
Changed to High RPM recording 3-8-10 RK
T03 Gbx HighSpeed Horizontal [Tach] Acc Wfm 8000 ms 6/23/2011 8:03:10 AM O/All 0.062 g RMS 1802.787 RPM
T04 Gbx HighSpeed Horizontal [Tach] Acc Wfm 8000 ms 3/14/2011 3:18:04 PM O/All 0.23 g RMS 1829.291 RPM
11. Bachmann electronic GmbH
PLANETARY SECTION
secs
0 10 20 30 40 50 60
g
-1
0
1
2
3
4
O/All 0.312 g RMS
Machine Note (3/8/2010 11:09:31 AM)
Changed to High RPM recording 3-8-10 RK
T04 Gbx Planetary Horizontal [Tach] Acc Wfm 64000 ms 3/14/2011 3:10:40 PM O/All 0.312 g RMS 20.484 RPM
T03 Gbx Planetary Horizontal [Tach] Acc Wfm 64000 ms 6/23/2011 8:10:43 AM O/All 0.035 g RMS 20.297 RPM
12. Bachmann electronic GmbH
CONDITION MONITORING MYTHS
. Need lots of data, lots of measurements,
with a baseline
. Too difficult to understand the data
. Not cost justified
. Cannot detect planet section issues
…..All condition monitoring is the same
16. Bachmann electronic GmbH
CONDITION MONITORING MYTHS
. Need lots of data, lots of measurements,
with a baseline
. Too difficult to understand the data
. Not cost justified
. Cannot detect planet section issues
…..All condition monitoring is the same
21. Bachmann electronic GmbH
CONDITION MONITORING MYTHS
. Need lots of data, lots of measurements,
with a baseline
. Too difficult to understand the data
. Not cost justified
. Cannot detect planet section issues
…..All condition monitoring is the same
24. Bachmann electronic GmbH
+/- 20% ACCURACY
BOTH ARE CURRENTLY BEING INSTALLED WITH OEM
CONDITION MONITORING SYSTEMS
WRONG SENSORS
+/- 20% ACCURACY
USING HIGH SPEED SENSOR IN LOW SPEED
LOCATION
25. Bachmann electronic GmbH
CONDITION MONITORING MYTHS
. Need lots of data, lots of measurements,
with a baseline
. Too difficult to understand the data
. Not cost justified
. Cannot detect planet section issues
…..All condition monitoring is the same