Lubrication of Space Shuttle main engine turbopump bearings

The Space Shuttle has three main engines that are used for propulsion into orbit. These engines are fed propellants by four turbopumps on each engine. A main element in the turbopumps are the bearings supporting the rotor that spins the turbine blades and the pump impellers. These bearings are required to spin at very high speeds, support radial and thrust loads, and have high wear resistance without the benefit of lubrication. The liquid hydrogen and oxygen propellants flow through the bearings to cool the surfaces. The volatile nature Of the propellants excludes any conventional means of lubrication. Lubrication for these bearings is provided by, the ball separator inside the bearing. The separator is a composite material that supplies a transfer film of lubrication to the rings and balls. New lubrication schemes and materials have been investigated at Marshall Space Flight Center in a bearing test rig with promising results. Hybrid bearings with silicon nitride balls were also evaluated. The use of hybrid, silicon nitride ball bearings in conjunction with better separator materials has shown excellent results. The work that Mai-shall has done is being utilized in turbopumps flying on the space shuttle fleet and will be utilized in future space travel. The results of this work are valuable for all aerospace and commercial applications where high-speed bearings are used.