Scavenging and turbocharging
Sleeve type bearings:
• Sleeve type bearings are lubricated by external L.O supply system. This is achieved either by – Gravity from independent header tank situated about six meters above the bearings to ensure that LO pressure never drops below 1.6 bar.
Or by – A main L.O pump leads to the bearings with a separate L.O pipe line. It has also gravity tank in case of failure of L.O supply. The system incorporates fine filters to avoid impurities and foreign particles.
Advantages of sleeve type bearing:
• Load carrying capacity is more. • It can run at higher temperature.
• Better inlet flow.
• Shorter rotor length
• Higher efficiency under full load condition.
• Time between overhauling is more than the other types of bearings.
Disadvantages of sleeve type bearing:
• At low speed/load create high friction.
Function of Labyrinth Seals:
• Labyrinth seals are of specially designed metallic fin type seals that separate the bearings from the blower and turbine.
• These seals are sealed by air supplied from the compressor volute casing is led into a space to prevent oil entering the blower and to prevent contamination of the oil by the exhaust gas.