Post on 06-Apr-2018
transcript
8/2/2019 Bhoruka Power ,Neria Report
http://slidepdf.com/reader/full/bhoruka-power-neria-report 1/6
Date: 01/03/2012
FINAL GEARBOX INSPECTION REPORT
SITE: BHORUKA POWER CORPORATION LIMITED.,
Neria Mini Hydel Scheme,
Village: Nidle, Taluk: Belthangady,
South Canara Dist.,
KARNATAKA
EQUIPMENT: TG Gearbox.
Power: 5050 KW. Unit Number: 1
Ratio: 2.885 Speed: 260 / 750 rpm.
Oil recommended: ISO-VG-320 Teeth Design: Single Helical
Oil Quantity: 147 Lpm Service Factor: 2.00
Driving Equipment: Hydel Turbine
Driven Equipment: Alternator
Further to the Preliminary report dated 28.12.2011, the gearbox tooth mesh was
inspected at site after decoupling the turbine and following observations made.
OBSERVATIONS:
a) Static blue teeth condition checked by decoupling both low speed and high speed
couplings.
Only 40% contact found towards alternator side.
Mesh Pattern in Both HS& LS Shaft Decoupled
Condition
8/2/2019 Bhoruka Power ,Neria Report
http://slidepdf.com/reader/full/bhoruka-power-neria-report 2/6
b) MOP dismantled from pinion NDE side and all gearbox foundation bolts were
Loosened and blue contact pattern was rechecked. Mesh pattern found same asabove.
c) Further pinion NDE thrust housing was loosened and blue contact recheckingwas done.
MOP Dismantled
Mesh Pattern
Mesh Pattern while foundation
bolts & thrust housing in loose Mesh Pattern in Non-active flank
8/2/2019 Bhoruka Power ,Neria Report
http://slidepdf.com/reader/full/bhoruka-power-neria-report 3/6
Contact pattern found towards pinion DE side for around 20% length of the total face
width.
d) Mesh Pattern checked on non-active flank and contact found towards pinion
DE for around 30% of the total face width.
After checking mesh contact pattern at different conditions at site, it was decided to take
the gearbox for TEIL works repair & rectification.
PRE RECEIPT CHECKS.
Before receipt of gearbox following in house checks were carried out on gearbox
performance data, quality, manufacturing and testing records
i. Review of raw material records did not show any deviation as regards to
ultrasonic, cleanliness, grain size, inclusions, chemical composition and
mechanical properties from standard requirements.
ii. Review of manufacturing processes confirmed that the subject pinion shaft has
gone through the standard processes and in- process checks. Records of no load
full speed test at Mysore also did not reveal any deviations.
To analyze this problem gearbox was brought back to TEIL works on 30.01.2012 and
Gearbox tooth mesh was checked using foundation stools to simulate site foundation
condition.
Casing Joint
Line
8/2/2019 Bhoruka Power ,Neria Report
http://slidepdf.com/reader/full/bhoruka-power-neria-report 4/6
Blue contact checked and found towards pinion DE side for around 35% length of the
total face width which was similar to what was found at site.
To understand the fragileness of casing the gearbox was then placed on the foundation
master using gearbox tank as support and mesh contact was checked.
Teeth Mesh contact found at the Centre for around 75-80% of the total face width as
Below.
Oil tray
8/2/2019 Bhoruka Power ,Neria Report
http://slidepdf.com/reader/full/bhoruka-power-neria-report 5/6
CONCLUSIONS:
From the detailed observations of the pattern of failure of pinion teeth, various tests,
checks and studies carried out, following conclusions have been deduced.
1. Raw material of pinion shaft is found to meet the design specifications.
2. The manufacturing processes followed are found in line with design
requirements. The tooth quality such as profile, helix, and PCD run out,
accumulated pitch error found confirming to the required DIN class
of accuracy.
3. The heat treatment processes followed have met the requirements of case
depth, microstructure and case hardness.
4. The review of MRT report suggests that the gearbox running parameters
such as casing vibration, noise and bearing temperatures were well within
the permissible limits during shop testing. The blue contact during open
inspection found 80-90% of the face width.
5. The tooth contact of gearbox at site during 2011 off season was observed
to be 40% as against 80-90% achieved at TEIL works during shop testing.
The tooth contact check carried out at TEIL works on receipt back of the
gearbox from site indicated contact pattern similar to that of site.
6. The teeth mesh was found improving from 40% to 80% when gearbox was
positioned on oil tray indicating presence of possible fragileness in the
casing.
8/2/2019 Bhoruka Power ,Neria Report
http://slidepdf.com/reader/full/bhoruka-power-neria-report 6/6
To summarize the tooth contact of the gearbox was found very sensitive to the gearbox
positioning. The casing bore coaxiality found varying depending on the method of gearbox positioning. This fragileness of casing is the most probable cause for the
tooth contact shift and pitting in the pinion.
The gearbox is provided with mesh adjustment mechanism for such eventualities at site
and usage of the same at site during installation could have avoided such end loading
and teeth damage if commissioning work was entrusted to TEIL. It is a general practice
to check the tooth contact pattern after erection of the gearboxes at site. Nevertheless
this mesh check will be carried out for this supply.
CORRECTIVE ACTION:
Teeth contact at site will be ensured to 80-90%(as obtained during testing at TEIL
facility) by TEIL service engineer after gearbox erection at site.
This check will surely eradicate the root cause of end loading due to which previous
failure had occurred.