NASA will upgrade the conveyor bearing units of its crawler-transporters

NASA has only 2 tracked vehicles in use for the transportation of carrier rockets like “Saturn” and the “Space Shuttle” on the launch pad at Kennedy Space Center. These are one of the world’s most existing engineering structures moving on tracks which are more than 45 years old. Despite the fact that the carriers were built in the 60s, they still have significant remaining life, and can still operate for decades after the upgrade which is planned by NASA.

NASACrawler-Transporter2A crawler-transporter carrying Discovery travels the ramp to Launch Pad 39B.

The upgrade work is underway for the conveyors of transporter CT 2, that will allow transporting more massive objects, expected as part of NASA’s plan to build a new launch platform. This will be the first time since the early 1970s. Modernization of the transport platform is part of the U.S. efforts to maintain the Kennedy space center in accordance with requirements of the 21 century.

Extensive tests were executed since November 2012 on the conveyor held drive, which identified design flaws. In February 2013 the conveyors were sent to the assembly complex. The next step was the dismantling and assembly of the new structures of the transmission parts.


NASACrawler-Transporter3Photo: NASA
replacement of bearings on Crawler Transporter 2 at the Kennedy Space Center

Initially, the nodes were supported by tapered roller bearings made from bronze alloy steel. Back in 1965, the tapered roller bearings could not stand the load of the platform during a test trip to the launching pad. The bearings could prevent deterioration of lubrication and heat dissipation, but failed to prevent the sudden destruction caused by the heavy loads.

Original designIllustration: NASA
The original design of the bearing assembly on basis of tapered roller bearings have failed the test trials

New designRevised bearing assembly on basis of the plain bearing
Difficulties with reduced friction and uniform distribution of the load on the body forced the developer of the roller conveyor back in 1965 to apply to the plain wheel bearings instead of tapered roller bearings

Currently, contractors are redesigning and upgrading bearing units with modern roller and plain bearings and lubrication systems, which are more advanced than what was used in earlier times. The main purpose of the work is to increase the durability and life of bearing units, which should provide payload transporter at least 6,700 tons of load capacity, and facilitate the easy replacement of the broken bearing during the operation.

Work on the modernization of bearing units are planned to be completed by August 2013, and closer to the end of the year the carrier shall be tested. After the modernization work, the platform transporter will work for another 50 years and will be a part of the new Space Launch System program by operating during the launching heavy space crafts to the Moon and Mars, from which the first will take place in 2017.

source: Based on public records of NASA