Needle Roller Bearings

Needle roller bearings are roller bearings, which have a high load carrying capacity with a very small section height. They are available with or without an inner ring.  In all needle roller bearings, except for full complement needle roller bearings, the needle rollers themselves are guided parallel to the axis by a dimensionally stable cage.   Airframe needle roller bearings are specified by MIL-B-3990 and National Academy of Sciences (NAS) standards.

Radial airframe bearings are designed for static loads and oscillation or slow rotation. They consist of an inner and outer ring with a full complement of needle rollers in a single or double row. These bearings must be supported by housings and mounted on high-strength shafts for maximum load capacity. Self-aligning designs can typically accommodate up to ±5° of dynamic misalignment.

Airframe track roller bearings have two basic designs for low speeds and heavy rolling loads. The yoke type consists of an inner and outer ring with a single or double row of needle rollers. This needle roller bearing assembly is not separable and has a high radial load capacity. The stud type incorporates an integral support member for cantilever mounting and moderate loads. The stud eliminates the need for a separate mounting bolt. A crowned outer ring is available for misalignment.

Typical application for aircraft needle roller bearings are for wing flap and slat track rollers, doors, in landing gear, and in hinges.  Design options may include seal design and material variations, options for lubricants and coatings for corrosion resistance.

Precision needle rolling elements used in needle roller bearings have multiple uses in a variety of industries including automotive, truck, farm and construction equipment, two-cycle engines, outboard engines and consumer durables. Needle rollers are mainly used as bearing rolling elements to transmit torque and reduce friction. They can also serve as precision shafts or as precision locating pins.

Standard roller material is high-carbon bearing hardened steel.  Needle rollers with a controlled contour profile are available to reduce end stresses. Needle rollers are typically shipped in bulk packaging. Some sizes may be supplied in wax-bonded strips for ease of assembly.

Other uses for needle roller bearings include crank pins, precision shafts and as locating pins.  Additional special features (knurls, grooves, etc.) and alternate materials (stainless or carburizing steel) are also available.

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Part Numbers for Needle Roller Bearings