Thordon Bearings manufactures a seawater lubricated propeller shaft bearing system that is unlike traditional water lubricated rubber bearing systems. It uses elastomeric polymer bearings designed uniquely to offer desirable performance and operational benefits. The low friction of the Thordon bearings and the early hydrodynamic film development creates an acoustically quieter bearing.
The COMPAC bearing is manufactured from a self-lubricating elastomeric polymer material with no grooves on the bottom section of the bearing as shown below. The bearing material does not have a shelf life and will not work harden in use. The COMPAC bearing is approved by all the major Classification Societies for use in a 2:1 L/D ratio (in position closest to the propeller), making it a much shorter bearing than traditional rubber bearing. With no grooves on the bottom half of the bearing, a smooth loaded section of the bearing is created. The advantage of a smooth bearing, in distinction from existing water lubricated grooved bearings, is the absence of the spaces where the water lubricating grooves would be located. The grooves when present, provide a channel for the hydrodynamic pressure to leak off. The absence of the grooves in the lower section allows the COMPAC bearing to establish a stable hydrodynamic film at lower shaft RPM than other water lubricated materials. With a grooved bearing, the hydrodynamic film is interrupted and must reform at the beginning of each bearing segment.
COMPAC Cross Section
A further advantage of the COMPAC bearing is its self-lubricating properties. When the bearing system is in the mixed regime, at lower shaft RPMs, contact between the shaft and bearing does occur. The low coefficient of friction of the self-lubricating COMPAC bearing minimizes start up torque and both friction and wear, during this contact period.