Crawler Transporter (CT) No. 2 at NASA’s Kennedy Space Center (KSC) was recently upgraded to increase lift capacity in anticipation of NASA’s the new Space Launch System (SLS) rocket. The weight of the new SLS is approximately 6 million pounds heavier than that of the Space Shuttle and to achieve this increased capacity, engineers from the Engineering Systems Division at NASA Ames Research Center designed upgrades to six crawler subsystems and three critical crawlerway transitions. Upgrades were made to include larger, redesigned roller bearings and their lubrication system; larger, redesigned jacking, equalizing, and leveling (JEL) hydraulic cylinders; larger 480 volt onboard generators; a larger crawler braking system; shear web structural stiffeners, and rebuilt gearboxes. Completed over the past 5 years, the crawler upgrades were just recently ready for final verification and validation testing, specifically to test the new JEL hydraulic lifting cylinders.
The crawler JEL system was tested statically while staying inside the Vehicle Assembly Building (VAB) at KSC, and later tested dynamically, as it rolled out to Launch Pad B. The system was first tested with no load on the crawler, then with an additional 9 million pound load. The JEL system’s function is to keep the load level on top of the crawler as it rolls out of the crawlerway and to allow vertical motion to drive under, and pick up, a Launch pad and launch vehicle. Engineers from NASA Ames also assisted in the rollout by installing and recording continuous strain gauge data on eight of the crawler shoes. This was performed on both the unloaded rollout as well as the 9 million pound rollout to validate the Ames recommendation to reuse the existing crawler shoes for the uprated load. The final tests were completed, with the system operating as expected which verified that the uprated crawler is capable of successfully carrying the new SLS rocket out to the launch pad.
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