Hello. I have a question in mind with regards to vertical pump thrust bearing, I would like to ask why is that vibration monitoring probe for the bearing are located radially.. why there is no vibration probe located axially or along the pump shaft?.

A vertical spinning shaft will develop vibrations perpendicular to the rotational plane therefore you would mount an accelerometer perpendicular to the shaft to record the amount of imbalance.

Thanks for so much for the idea... do we need also to consider the axial thrust of shaft? Thus the axial thrust for the vertical pumps can be neglected for monitoring?

The movement created axially will not be due to imbalance, however there should be a trust bearing to control any axial movement.