CAMTECH/97/E/TM/3.0
TM Maintenance Handbook January’97
30
CHAPTER 3
FAILURES AND TESTING
3.1
COMMON FAILURES, CAUSES & REMEDIES
SN
FAILURE/ TROUBLE
POSSIBLE CAUSES AND REMEDIES
1.
POOR COMMUTA-
TION
CARBON BRUSH
i) Grade or form :
Examine the grade of carbon brushes
If found different, replace with the same grade of
brushes.
ii) Wear/damage : Side wear of carbon brushes makes
gap to holder case bigger and so replace with a new
one.
Iii) Chattering/vibration: Remove oxygenated film of commu-
tator surface or change grid of carbon brushes.
iv) Sticking of brushes: Remove dust and check gap to
holder case.
v) Copper picking or spotting: Copper powder sticks to
commutator surface and oxygenated film becomes un-
equal. Change grade of brush.
vi) Unbalance of brush current : Colour change in pigtail of
brush. Strike on commutator surface and contact of
brush to be checked .
vii) Wearing out of brushes: Lift-up of carbon brush causes
spark and damage. Replace with a new one.
BRUSH HOLDER
i) Wear of inside of carbon way: Measure the dimensions
of brush holder and replace it ,if required.
ii) Improper attachment of brush holder : Crookedness,
pitch, gap should be examined and adjusted.
iii) Improper spring pressure : Check pressure and adjust
as designated.
