TORSIONAL VIBRATION in marine propeller drive line
TORSIONAL VIBRATION in marine propeller drive line
(OP)
Bad vibration in 45" 22000 lb boat at 2600-2900 engine RPM
480 hp diesel engines 3300RPM max 2.00 to 1 reduction transmission vulkin coupling between engine and trans has been fine in other installs. We have tried five and six blade propellers. Six is better even thought the blade pulse with the water is exactly overlaping the 6 cylinder engine pulse. The drive line consists of 6 cyl engine Vulkin damper ZF trans flange yoke to 1710 dana spicer U joint 65" to second U joint properly phased to a bearing that takes propell er shaft thrust to the boats hull. Drive line is at 6.3 degrees ok by Dana. (CV joints do not fix the problem) From bearing to splined surfacing propeller is a 2" shaft 57" long.
I am looking for tube in tube drivline dampers or tricks in u-joint phasing that might offset the vibration. peaks show at 120,160 and 320 HZ. any ideas?
480 hp diesel engines 3300RPM max 2.00 to 1 reduction transmission vulkin coupling between engine and trans has been fine in other installs. We have tried five and six blade propellers. Six is better even thought the blade pulse with the water is exactly overlaping the 6 cylinder engine pulse. The drive line consists of 6 cyl engine Vulkin damper ZF trans flange yoke to 1710 dana spicer U joint 65" to second U joint properly phased to a bearing that takes propell er shaft thrust to the boats hull. Drive line is at 6.3 degrees ok by Dana. (CV joints do not fix the problem) From bearing to splined surfacing propeller is a 2" shaft 57" long.
I am looking for tube in tube drivline dampers or tricks in u-joint phasing that might offset the vibration. peaks show at 120,160 and 320 HZ. any ideas?





RE: TORSIONAL VIBRATION in marine propeller drive line
My guess is however, that you have a resonance problem with the engine or gearbox on its mounts. Just feel with stretched finger where the highest vibration occurs.
RE: TORSIONAL VIBRATION in marine propeller drive line
We had acoustic testing Saturday and I hope to see the results perhaps today.
ZF has a large facality here and that is where the couplings came from so I will heed your advise an consult with them.
I played with the boat this weekend with six blade props.
The vibration moves around the boat as the engine RPM changes. From 2600-2900 it is bad, hatches buzz you can see the floor move. I have a high quality strobe and watched the drive lines for a long distance at the worst vibrations. They are smooth just a tiny movment at the thrust bearing can be felt but it is a fraction of the floor movment.
RE: TORSIONAL VIBRATION in marine propeller drive line
The drive shaft is not a cardan shaft is it? If so, check the yokes (should be in the same plane) and the in and out angles (should be identical)
good luck.