Bearing Categories and Models for Aerospace

Airframe and aircraft control bearings fall into several standardized categories, each serving specific functions within the aircraft structure and control systems.

Ball Bearings (Airframe Control)

Ball bearings are widely used in airframe applications where loads are primarily radial and movements are often oscillatory or involve limited rotation. Industry standards such as SAE-AS7949 (formerly MIL-B-7949) govern their manufacture . Common series for airframe applications include:

• Single Row, Rigid, Sealed: These are used in various control mechanisms and are available in light, intermediate, and heavy-duty versions in both inch and metric series . They often feature increased precision and reduced internal clearances for tighter control .

• Double Row, Rigid, Sealed, Heavy-Duty: Designed for higher load capacities, these bearings are often "full complement" (without a cage) and have a double row of balls, filling slots, and are built to withstand slow rotations and oscillations under load. They operate in a temperature range from -54°C to +150°C .

• Torque Tube Design: These specialized light and extra-light duty bearings are designed for use in torque tube applications, which transmit rotational force within the airframe .

• Self-Aligning Bearings: These accommodate misalignment and are available in light and heavy-duty options for various applications .

Roller Bearings

Roller bearings provide higher radial rigidity and load capacity compared to ball bearings. They are used in applications requiring the accommodation of heavier loads or defined axial movement . Airframe control roller bearings are also available, including self-aligning roller bearings, and are manufactured to conform to SAE-AS7949 and major OEM specifications .

Sliding Bearings (Plain Bearings)

Journal bearings, also known as plain bearings or bushings, are critical for airframe, helicopter, and landing gear applications. They are often designed with self-lubricating liners .

• Mil-Spec and SAE Standards: These bearings come in standard and flanged series, often conforming to standards like AS81934 (formerly MIL-B-81934) .

• Materials: Standard materials include 17-4PH stainless steel and aluminum alloys. They can be cadmium or zinc-nickel plated for enhanced corrosion protection .

• Liners: Self-lubricating liner materials are key. The AT 3200 bearing liner system is common, as are other machinable liners qualified for specific performance characteristics like high-temperature resistance for turbine engines.

MTWB Customization Portfolio

MTWB experience in customizing bearings is extensive, particularly for OE customers. Their portfolio includes a wide variety of customized bearing types that directly apply to aerospace :

• Special Dimension Bearings: Deep groove ball bearings (DGBB), cylindrical roller bearings (CRB), tapered roller bearings (TRB), and angular contact ball bearings (ACBB) can all be manufactured to non-standard dimensions.

• Super Precision Miniature Bearings: For high-speed, high-accuracy instruments.

• High and Ultra-Low Temperature Bearings: For the challenging thermal environments encountered in aviation.

• Stainless Steel Bearings: For corrosion resistance.

• Maintenance-Free Bearings: Featuring self-lubricating properties, a key advantage for components that are difficult to access.

• Guide Roller Bearings: With V, U, G, or W grooves for specialized guidance systems.