BINSFELD ENGINEERING INC.

Damaging Torsional Vibration Identified & Eliminated

Damaging Torsional Vibration Identified & Eliminated

CENTA Transmissions Far East Pte. Ltd. used the TorqueTrak 10K telemetry instruments from Binsfeld Engineering to diagnose and solve a problem aboard their customer’s twin-prop ship, where the couplings on both shafts repeatedly suffered damage after only a couple hours of sea trials. They would replace the coupling elements with new parts and the same damage would reoccur. Their shipyard checked the alignment, found nothing wrong, and once again replaced the coupling elements only to run into the same damaging results.

Their Torsional Vibration Calculation (TVC) report showed no abnormalities but they knew something was not right. At this point they decided that they needed to look deeper into the issue and so they looked to Binsfeld’s TorqueTrak 10K for answers. Two TT10K units were mounted into their system to monitor the torque on each shaft.

Their testing revealed the presence of signicant oscillating torque when the Controllable Pitch Propeller (CPP) was at 50 to 60 percent. They were able to determine that the torsional vibration was signicant enough to cause their recurring element damage.





 

 
 

 
 
 
They did another TVC using a coupling with different shore hardness. They replaced the starboard side coupling with a 50SH element while keeping the port side as it was originally, and then made new measurements with the TorqueTrak 10K instruments. This time the report showed a surprising difference.



 
 
 
You can see in the STBD shaft the high vibratory torque that was previously present no longer exists. Armed with this information they replaced both elements with new ones rated at 60SH. This greatly reduced the torsional vibration strain and eliminated the breakage of couplings.