High precision technology company, Taylor Hobson, has been enlisted by NASA’s Marshall Flight Centre to provide ultra-precision measurement systems to perform critical surface analysis of a damaged bearing assembly from the International Space Station. The Talysurf PGI 1230 Surface Measurement and Talyrond 295 Roundness/Cylindricity Measurement systems were both required to ensure analysis was carried out with the highest levels of precision.
The results are expected to help NASA experts determine the cause of the damage to the Solar Alpha Rotary Joint (SARJ), a 10 foot diameter ring that allows the station’s solar panel array to rotate and track the sun. Until the cause is found and the problem fixed, the station’s starboard solar array cannot be properly rotated for optimum power generation.
A damaged Trundle Bearing Assembly, one of twelve aboard the starboard SARJ, was removed and returned to earth aboard the space shuttle. Along with the damaged bearing assembly, a team from NASA’s Marshall Space Flight Centre measured 17 spare units and 12 others that had been life tested aboard a test SARJ. The team conducted an extensive examination of the bearing assembly, including extensive dimensional and surface profilometry measurements using the Talyrond 295 and Form Talysurf PGI 1230 from Taylor Hobson.
Each trundle bearing assembly includes three rollers, each of which is essentially a tapered roller bearing comprising a tapered sleeve fitted onto an internal rolling element bearing. The positions of the rollers in their housings, along with the clearance requirements of the styli on the Taylor Hobson instruments, presented some unique challenges for the NASA team.
Relying upon the Talyrond 295, a high-precision roundness/cylindricity measurement instrument, outfitted with optional Radial Straightness Unit for axial profiles, whilst the Talysurf PGI-1230 was used for circumferential profiles of the surface. Using some very imaginative part positioning, the team were also able to take advantage of the unique versatility to, in effect, use a “roundness” machine to measure straight features, and a “straightness” device to determine the round features.
Profilometry confirmed that the roller surface geometries of the bearing assemblies were manufactured to original specifications and that the wear profiles corroborate dynamic computer models and high-fidelity traction test results.
The information gathered using Taylor Hobson’s high-precision instruments will aid the NASA team in the selection of preferred Trundle Bearing Assemblies for flights as will as their potential for reuse in orbit.