Tilting Pad (Pivoted shoe) Thrust bearing and Lubrication

Each bearing consist of a series of pads supported in a carrier ring, each pad is free to tilt so that it creates a self-sustaining hydrodynamic film.

The carrier ring may be in one piece or in halves with various location arrangements.

Two ways of lubrication in the bearing:

1.  Flooded lubrication

• Flood the housing with oil, using an orifice on the outlet to regulate the    flow and maintain pressure (Housing pressure- 0.7 to 1.0 bar ) to minimize the leakage.
• Seal rings are required where shaft passes through the housing.
• Simple but results in high parasitic power loss due to turbulence at high speed.

                                                        Flooded Lubrication

2. Directed lubrication

• Where mean sliding speeds in the excess of 50m/s are expected the losses in the flooded lubrication can be eliminated by employing directed lubrication.
• Reduce power loss by 50%.
• Reduce the bearing temperature, also reduces the oil flow in most cases.
• No seal rings are required on the shaft.
• Oil supply pressure for directed lubrication is 1.4 bar.

        

                                                     Directed Lubrication

Note:-

• Directed and flooded bearing have same basic sizes and use identical thrust pads.
• The bearing housing must be kept free of bulk oil through an  simple drain area around the collar periphery.
• Oil velocity in the supply passage should not exceed 3m/s to ensure full pressure at the bearing.

Hydraulic thrust metering arrangement

A hydraulic piston is located behind each thrust pad and is connected to a high pressure oil supply. The pressure in the system then gives a measure of the applied thrust load.