Description:
OBJECTIVE: Develop a new wheel bearing for use in a highly loaded moving shuttle subjected to high acceleration and deceleration rates to reduce the maintenance and other resources required to maintain bearing components. DESCRIPTION: There is a need for development of an advanced wheel bearing with long life under high loads, and high acceleration/deceleration rates. Currently, open and sealed wheel bearings are utilized, but both require greasing as frequently as every 25 launches. The high periodicity of greasing creates both environmental and operational burdens. Life considerations should be paramount; graceful degradation, low maintenance and low replacement frequency are ideal. The proposed wheel bearing should not require periodic greasing. Proposed wheel bearings should have long life without exhibiting signs of degradation or loss of grease which would affect performance. Any bearing failure must remain contained to prevent having a Foreign Object Damage (FOD) hazard. The wheel bearing technology should take into account Electromagnetic (EMALS) and Steam catapult requirements. The Electromagnetic armature has 6 wheels and the Steam catapult shuttle has 8 wheels in a vertical configuration on a horizontal axis. Approximate requirements for the EMALS and Steam Catapult applications: Application acceleration: 0 to 180 knots (kts), within 300 feet (ft) Peak acceleration: 5.5 G"s Application deceleration: 180 to 0 kts, within 20 ft Threshold(T), 5 ft Goal(G) Maximum distance traveled per acceleration/deceleration cycle: (2x) 350 ft Operating temperature range: -20 degrees Fahrenheit (F) to 160 degrees F (T), 250 degrees F (G) Environmental: Humidity, rain, salt fog, salt water spray, contaminants, sand & dust, nuclear, biological, and chemical (NBC) decontamination, and magnetic environment Basic dynamic load rating: 25,000 pounds (lbs) (T), 65,000 lbs (G) (based on basic life (L-10) of 1 million revolutions) Basic static load rating: 150,000 lbs Dimensions of bearing (approximately): 6.3 inch (") Outer Diameter, 3.5"Inner Diameter, 2.4"width Life (approximate cycles): 5,000(T), 25,000(G) PHASE I: Develop and demonstrate feasibility of a long life wheel bearing technology that meets the key requirements and technical issues referred to in Description. PHASE II: Design and develop a prototype based on the Phase I concept. Demonstrate the prototype performance during full speed launches with no loads on catapult test sites. PHASE III: Finalize testing and transition the technology to the appropriate platforms and the Fleet. PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: This wheel bearing development may be applied to many applications in the commercial sector as well as for other military agencies. This technology is important to the future of locomotives, aircraft, spacecraft, and electrical vehicles. REFERENCES: 1. Dick, M.G., & Wilson, B.M. (2006). The Effect of Sustained Wheel Impacts on Tapered Roller Bearing Cages. Proceedings of the 2006 IEEE/ASME Joint Rail Conference, 189-195. doi: 10.1109/RRCON.2006.215309 2. Harris, T.A., & Kotzalas, M.N. (2006). Advanced Concepts of Bearing Technology (5th ed.). Boca Raton: CRC Press.
