Needle roller applications in aerospace
Like most applications requiring needle rollers, the predominating requirements are high load carrying capacity in a small compact bearing format. The needle roller bearing suits this requirement perfectly.
A needle rollers contact with the raceway essentially equates to a line (as opposed to a ball bearings “point contact”). This gives the needle roller bearing its higher load bearing capability. This linear contact point does however create more resistance to rolling and consequently the needle roller bearing cannot achieve the higher speeds obtainable with a ball bearing.
Although not capable of supporting any axial loads placed upon it, the needle roller bearing can take high radial loads at slow to medium speeds. For higher load applications a full complement of needles (i.e. no retainer or cage mechanism) should be used. The trade of here is a lower tolerance to medium speeds. Where applications run at medium speed then a needle roller with a retainer or cage mechanism should be deployed (of course this leads to a reduced load capacity).
Needle roller bearings for aircraft are predominantly found in the wings, being used on the slat and flap carriages. Their ability to support high loads and often-high vibratory loads is essential. McGill, Torrington and RBC all specialize in needle rollers which fit this specific requirement. The ranges of needle rollers that are used on wings are called cam and yoke rollers. Clicking the manufacturer names above can use more details on these designs. Needle roller bearings can also be found on aircraft door mechanisms and landing gear extension/retraction support struts.
Advances in material technology have enabled bearing manufacturers to push the needles bearings endurance way beyond what it was 20 to 30 years ago. This coupled with advances in bearing seal design and materials, lubrication performance and more detailed maintenance have lead to significant improvements in needle roller performance.
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