M/e thrust bearing structure

Structure : Main Engine thrust bearings are tilting pad type, a thrust collar is forged internally with the thrust shaft, both on forward and aft side of the collar, thrust pads are fitted, thrust pads are lined with white metal & faces the highly machined and polished surface of the thrust collar.The back of the pad has a structure which forms a fulcrum on which, the pads can tilt.The fulcrum comes in contact with the solidly constructed housing. A oil pressure is developed between the pads and the collar when the shaft is rotating due to the formation of an oil wedge. as the pads can tilt, it becomes self adjusting to the shape of the wedge. the tilting pads are bean shaped otherwise the leading edge of the thrust pads will become oil scrapers negatively affecting the formation of oil wedge. Indication of faulty operation 1. high temperature of lube oil. 2. Check the intermediate shaft during reversing, small axial movements of shaft is sign of fault. Measurement of thrust bearing clearances: 1.Using feeler gauge- the thrust bearing is opened up and by using jacks or wedges thrust collar is pressed hard on set of the thrust pads, long feelers are inserted on the side which is open. The feelers should be long enough to extend from one corner of the pad to the corner diagonally opposite. they must be inserted on one corner and diagonally eased up through the other, so clearances can be taken without tilting the pads.( if the collar cannot be hardened to any side, we can take clearances on both side and add. 2. Using dial gauges- without opening up, the collar is pressed hard using jacks or wedges, then the axial shift of shaft (clearance) is measured on the dial gauge. normal value of clearance- .35mm (value low because no wear since no metal to metal contact. the clearance can be corrected by adding shims between back-plate and housing).