Power Pack maintenance

Recent spate of failures of Power Pack components is a cause of major concern.

Power Pack maintenance practices should be reviewed by each Shed and measures suggested below should be incorporated with immediate effect.

1.   Ensure Proper lubrication

 Lubrication is heart of power pack functioning and availability of clean lube oil should be ensured by

·     Cleaning of Centrifuge: Centrifuge cleaning should be done in 30 days schedule. Sludge deposited should be weighed & functioning of Centrifuge should be checked by measuring RPM & quantity of sludge deposited.

·     Cleaning of sump, block and lube oil header:  Cleaning of lube oil pathway, sump &block during M₂₄ schedule should be scrupulously  done & lube oil passage should be wiped dry by lint free cloth. Lube oil headers should be cleaned, Lube oil passage should be checked & holes should be cleaned by rounded metal wire. Adequacy of lube oil flow should be checked in cylinder head, FIP support, cam gear by opening covers. Cam nozzles should be cleaned by wire & hole to be elongated to 3.2mm dia. Test filters should be used during major schedule. During M₂₄ /M₄₈ & POH pre-commissioning, lube oil should be changed after 100 hours of service & fresh oil should be topped up. Released lube oil can be used in inferior services.

·     Condition of filters: Released lube oil filters should be visually examined for filter condition sludge deposit, pressure drop & pleat condition.

·     Condition monitoring of lube oil should be done by blotter test, viscosity index & spectro report. Corrective measures should be taken during medium & above schedule based on above reports.

2.   Effective cooling

Temperature differential of incoming water & lube oil should be measured in engine block. A standard bench mark for temperature differential should be fixed & if temperature differential is falling then cooling needs to be improved.

Before stripping for M₂₄ schedule,  dilute HCL dose(less than 5% concn: as recommended by lab) should be used as descaling agent & loco should be run for six hours to dislodge the scale in engine block & pipe line. This de-scaling should be done before stripping only, to avoid damage of rubber components. Similarly in-situ recirculation should be done for cleaning radiators.

When heat exchangers are taken to section; oil, air & water path should be meticulously cleaned. Re-circulation with air stirring of hot solvent should be done. Effectiveness of cleaning should be judged by measuring temperature differential before & after M₂₄/M₄₈ schedule.

Water stabilization temperature should be measured at load box & should be kept below 75° for WDM_3A/₂ locos. The stabilization temperature should also be recorded during footplating and reading should be compared with load box reading. Water stabilization temperature reading should be made part of driver repair book format.

3.   Effective Air Supply

Good combustion depends upon availability of clean supercharged air in combustion chamber. This can be ensured by changing baggie air filter in quarterly schedule. Initial pre-filters should be attended/replaced during M₁₂ & above schedule.

After coolers must be clean & tubes should not be dummied. Air path must be sealed to ensure only filter air enters the combustion chamber. Released air filter should be examined by lab for filter quality, dust deposit & filtration efficiency. Pressure drop across air filters should be measured in M₄ & above schedules. Over aged filters should not be used as oil coating becomes dry.

4.   Efficient Combustion:

Cylinder head blow bye and compression test: These tests should be carried out in every quarterly and above schedule and power assembly should be replaced accordingly. Firing and compression readings should be taken during load box in medium schedules and above. Power assemblies having lower Kiene gauge readings should be replaced/overhauled.

Condition of nozzles should be checked 100% during M₁₂ schedules and  on sample basis during M₄ schedules as dribbling nozzles result in improper combustion, high soot formation and oil dilution.

5.   Replacement of cam gears and their Alignment 

Alignment and condition of camshaft, cam gears & split gear plays major role in power pack performance.

Cam shafts, cam gears, split gears & cam bushing should be replaced during M₂₄/₄₈ schedule. Before replacement of cam bush, condition of cam bush housing should be checked for ovality & welding integrity.

Cam gears must be checked during M₄ & above for wear and pitting by lab. Ovality of cam bushing, welding condition and wear should be checked in medium schedules; cam bushings should be replaced during M₂₄. L9/R9 locations are extremely prone to failures and must be checked for wear, ovality & welding in every schedule. Cam shaft run out should be checked during M₂₄ Schedule and should be kept below 4 thou.

Proper tools for extraction & fitment should be provided. Hydraulic puller/ pusher should be used for fitment and extraction of cam bushes, cylinder liners. Cam gears should not be cut/damaged during extraction. Anti-seizure compound should be used during fitment and recommended solvent should be sprayed for removal. Cam shaft flange, joining bolts should be properly tightened & thread locker should be used.

6.   Condition monitoring: Critical parameters like exhaust gas temperature, water stabilization temperature, eight notch rack, rack variation & zero error, centrifuge sludge deposit, temperature differential across block and heat exchangers, CDT, sudden notch down lube oil pressure differential and sudden notch up lube oil pressure build up and rpm differential must be recorded in every schedule.

Implementations of the above measures are essential for improving power pack reliability. Feedback on action taken should be reported through MCDO. Importance of these measures must be explained to concerned sectional staff & Supervisors.