Ceramic Airframe Bearings.
Final rept. 22 Feb 73-22 Feb 74,
BOEING AEROSPACE CO SEATTLE WASH
Pagination or Media Count:
A ceramic-solid-lubricant material screening test program was conducted to select materials and lubricants for a plain spherical bearing design. Friction and wear screening testing was conducted at stress levels to 7500 psi using PTFE, graphite and molybedum disulfide lubricants. Best performance was obtained with an alumina rider specimen sliding against a silicon nitride plate lubricated with an MoS2 solid lubricant compact. A lubricant reservoir bearing design development program was conducted. The manufacturing details for fabricating plain spherical bearings using AD995 alumina balls in contact with an alumina lubricant reservoir race are described. Four bearings indicated low wear when tested for 50 hours in a simulated helicopter rotor pitch link test. These tests were conducted for 50 hours at 243 rpm with pitch link loads of 275 plus or minus 925 pounds and a swashplate tilt angle of 9 degrees. Tests conducted under simulated hydrofoil flap bearing operation resulted in fracture of the ceramic outer race. These tests were conducted as a load spectrum increasing in 1000 psi increments while oscillating plus or minus 10 degrees at 20 cpm. The highest load capacity attained was 8570 psi. Author
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