12-21-2011 01:09 PM - edited 12-21-2011 01:24 PM
Hi people, My name is Donald.We have two MaK 6m 332AK engines fitted as main engines.Our port main engine has developed a vibration problem.At certain rev's we are getting a lot of vibration from it (380-535) rev's. At 550-560 rev's it seems to disapear alltogether,but when you stand at the free end of the engine you can still feel it but it is very minamal.The starboard engine does not suffer from these symptoms and runs very smoothly.I have checked the shaft and plumber blocks and there is no vibration or overheating along it's length.I have also checked that the lateral tie bars are tight and a crankcase inspection was carried out.The effects of the vibration is more evident from the free end of the engine. If anyone has any ideas please post.
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12-22-2011 11:05 PM
I run several EMD 12-645 engines and they always vibrate on the free end. You can actually visibly see the engine shaking. But, the front isn't bolted down tightly, usually 4 1" bolts at 150 ftlbs. The rear gets 4 1" bolts at 450 ftlbs with taper pins as well.
If you think you've got a problem perhaps you should bring in a vibrations specialist who can put accelerometers on the engine and first determine if there is a problem and then pinpoint the source of the problem. I would also pull pressure vs. crankangle curves for each cylinder, if possible, to determine if the engine is firing evenly across all cylinders.
06-27-2012 03:23 PM
It sounds like there is an issue with the vibration damper, which is integral with the oil pump drive, mounted on the free end of the crankshaft. I would check the balance weights in vibration damper.
If one of the balance weights or bushings are worn out or have been flat spottted the weight will not roll freely causing an out of balance issue at certain RPM's and cause the vibration issues you are experiencing.