[MBmaint]

Have a Mazak FJV-35 Vertical Milling Machine, having a problem with the spindle lube system where the return pump is not returning the ISO 10 spindle oil back to tank as quickly as it is being fed causing an overflow from the head. At first assumed it was the return pump that was at fault but tested this and it returning oil efficiently.

The problem seems to be that the return line is drawing air from a breather/overflow that comes from the top end bearing at the input shaft to the spindle gearbox. The line and connections themselves are intact so it looks like it shouldn't be able to draw air through this path which is causing me to wonder if there is a seal away that is allowing air to enter the bearing housing that should be air tight???

It is hard to determine this from the mechanical drawings as they are crap.

Anyone encountered this kind of problem?

[sivaraj]

It most important to verify the fixing orientation of L-bow connector on the pump outlet. The L-bow connector orientation on the outlet should pointing a bit downwards so that outlet hose bends bit downwards and goes up.You need to maintain this to avoid oil on the outlet hose drain out or which helps priming.