Babbitt thrust bearings are sensitive to many parameters. Hydro thrust bearing failures are typically due to:
- an excessive load capacity often because turbine efficiency is increased
- a lack of oil due to oil pump failures
- oil viscosity is too low to maintain an efficient oil wedge during slower rotational speeds
- high temperature rises of oil because of lack of cooling water or low rotational braking speed
- contaminants in the oil such as babbitt residues from the guide bearing
- a misalignment of two halves thrust runner plate
PTFE Thrust bearings offer many advantages and solve these problems because:
- have a higher admissible specific load capacity up to 6.5MPa(943psi)
- can increase capacity up to 200%
- have a greater flexibility; thus, eliminating cracking
- have a lower coefficient of friction (0.05-0.08) which results in lower oil temperature in pot
- are not sensitive to contaminants in oil
- can hot start after stop
- perform well at low speeds because the wedge profile is optimized to maintain the lubrication
- withstand 3 times the temperature rises of that of babbitt
- work best for pump storage because the pivot point is closer to the center
- do not require a high-pressure lift system
