Voith coupling 900 RPM "pretty big" for exhaust fan with multiples on input shaft speed 4x and 5xRPM dominant H/V 10-14mm/s 3xRPM axial. Was ok before, under 2mm/s. 2 buddies also ok. Was sent for overhaul for this problem when it popped up, same still misbehaving when put back. What can be loose inside that thingy? Olov

Some of these have higher than expected axial on:

A-------B---[]---C-------------D


E-------------F

Position "E" (aligns up under Pos C). It is a characteristic of certain models of these units. However, not out 5 places and less than 0.2 IPS or thereabouts.

But, I can be entirely wrong about your particular unit. It would be advisable to contact the OEM on this. I had worked with the German rep on a 17,500 HP unit.

Olov,

If ALL bearings were replaced during overhaul, then either the bearing fits are incorrect or the rotor fit on shaft is incorrect. If the fits are (feel) tight when cold, then looseness could still occur when reaching operating temperature from differential expansion. The next overhaul should be conducted by another company or at least with an experienced independent review of all work during the overhaul. I also recommend rotor inspection for cracks and a good shop balance.

Walt

Thank´s, there has been another refurb on a similar unit at another place where the shop balancing was found to be way out and had to be reworked. I don´t know if it´s been done by the same company. Olov