A commercial aircraft consists of approximately 6 million parts, with a maximum takeoff weight that can exceed 500 metric tons. With every safe takeoff and landing, hundreds of passengers and this intricate system ultimately rest on just a handful of landing gear wheels. Inside these wheels, Timken® aviation landing gear bearings must withstand drastic changes in load, rotational speed, and temperature during the landing process.

 

The moment the aircraft touches down, the load from a large passenger jet is transferred to the ground through the landing gear. The wheels, which had not previously made contact with the runway, immediately begin to rotate rapidly, with rotational speed increasing in an extremely short period of time; subsequently, as the aircraft begins to decelerate, intense heat generated by braking sets in. Prior to touchdown, the wheels had also endured sub-zero temperatures at an altitude of 30,000 feet (approximately 9,100 meters).

 

 

Coping with the combined challenges of high loads, instantaneous increases in wheel speed, and operation across a wide temperature range relies on the combined efforts of materials, design, manufacturing, application analysis, and maintenance support. For Timken, “systems-first” means starting with the application of the entire aircraft, understanding the actual operating conditions at different critical locations, and then responding to specific needs with appropriate products and engineering capabilities.

 

Starting with the Landing Gear Wheels

Serving More Critical Aviation Applications

 

In the landing gear wheel assembly, Timken® tapered roller bearings with the 629 performance code feature a two-stage quenching and carburizing heat treatment, precision internal geometry, and a combination of engineered surfaces and the ES300 engineered coating. Tight manufacturing tolerances help the bearings withstand the repetitive peak loads encountered during landing; the engineered surface, coating, and proprietary internal geometry help improve wear, fatigue, and friction performance in the contact area between the roller end faces and the flanges.

 

Aircraft wheels are just one of many critical locations on an aircraft. In the landing gear struts, GGB® sliding bearings are used to meet the load-carrying, motion, and durability requirements of these locations; in control surfaces and cabin systems, Aurora® rod-end bearings and Rollon® linear guides serve precision control and linear motion applications, respectively. Each brand is tailored to different operating conditions, collectively expanding the boundaries of our capabilities in serving critical aerospace applications.

 

 

In engine and gearbox applications, Timken® ceramic hybrid bearings feature steel rings and ceramic rolling elements. Ceramic rolling elements can be up to 58% lighter than steel rolling elements of the same size, while offering 50% greater stiffness, providing greater design flexibility for weight reduction, high-speed and high-temperature operation, and optimization of overall system efficiency.

 

Reliable Operation

Starts with Design

 

The reliability of aerospace bearings is established right from the design phase. Our aerospace bearing analysis capabilities are built on more than 80 years of test data and over 30 years of application experience. We use dynamic modeling and thermal modeling to evaluate bearing performance under actual load, speed, and temperature conditions.

 

Finite element analysis and virtual bearing life testing are further utilized to evaluate structural stresses, load conditions, and material properties. For specific applications, our engineering team also provides support in areas such as dimensional tolerances, CAD drawings, and metallographic analysis.

 

From Manufacturing to In-Service Operation

Sustaining Reliable Performance

 

Bii, a Timken company located in Southern California, has been engaged in the inspection and repair of aviation bearings since 1955. Its capabilities cover more than 5,000 aviation ball and roller bearing part numbers, helping 36,000 bearings return to airworthiness each year. These services are designed for applications such as aircraft engines, gearboxes, auxiliary power units, and accessories, and can support a wide range of non-Timken brand bearings.

 

Timken’s Chengdu Aviation and Precision Products Center, which opened in 2008, serves as the company’s aviation bearing manufacturing and inspection base in China. It holds dual Part 145 maintenance organization approvals from the Civil Aviation Administration of China (CAAC) and the Federal Aviation Administration (FAA), as well as AS9100D quality management system and NADCAP special process certifications, providing localized manufacturing and inspection support to Chinese aviation customers.

 

In China, engineering and customer support teams are located in 10 major cities. With an average tenure of over 10 years, team members assist customers with application analysis and service requirements; specific inspection, repair, and release tasks are performed by approved facilities within their respective scopes of authorization.

 

Since entering the commercial aviation sector in 1935, we have consistently integrated product design, engineering analysis, precision manufacturing, and professional services. From a single landing to an inspection and back to the air, our “systems-first” approach ultimately ensures reliable operation at every critical point.