How Are Aircraft Wheels Designed and Constructed?
The wheel assembly of an aircraft is paramount for its ability to land and traverse solid surfaces, tasked with taking on large amounts of wear and tear through normal operations. As the wheels must be capable of withstanding the load of the aircraft and are fitted with disc brake systems that enable high stopping power, they are robustly designed in regard to their materials and construction. In this blog, we will discuss the design and construction of aircraft wheels and how they benefit landing operations.
While the design of landing gear systems may vary by aircraft, the wheel assembly is generally a two-piece construction cast or forged from either aluminum or magnesium alloy. To assemble the two wheel pieces, mating surfaces will be fitted with an o-ring and bolted together. The rim of the wheel is sealed due to the fact that tubeless tires are the most common tire type for modern aircraft. During the construction phase, it is also important that the bead seat is strengthened as it is the area that comes into contact with the wheel and will undertake a large amount of tensile loads during a touchdown.
The two halves that come together to form the wheel assembly are not identical, due to the fact that they are attached to different components and systems. Unlike the outer wheel half, the inboard wheel half requires the ability to accept and drive rotors belonging to the brake system. With tangs attached to the rotors, connection to the wheel can be established with steel reinforced keyways. Steel keys which are bolted to the inner half are also an option, permitting the brake rotor to fit in slots.
For high performance aircraft in particular, the inner wheel half will typically have one or more thermal plugs for the means of protecting the assembly. When an aircraft undertakes heavy braking, the rapid rise of temperatures from friction and high pressure pose the risk of a tire and wheel explosion. With thermal plugs, an alloy core will melt when a certain threshold of temperature is reached, resulting in the deflation of the tire. Heat shields are also a common addition to support such safety endeavors. As the melting of the thermal plug alloy causes deflation, aircraft wheel assemblies should be removed and inspected after and must be serviced before being reinstalled.
The outer wheel half is the half that the tire is mounted on, featuring a center boss which is specifically constructed to receive a bearing cup and assembly. The outer wheel bearing and axle end are typically capped so that contaminants cannot enter the section. If the aircraft has been designed with an anti-skid brake system, there will often be a wheel-spin transducer that is affixed to the outer wheel half and may be sealed. Sealing is typically conducted to create a hubcap fairing, that of which will fair the wheel with the wind. Generally, the outer wheel half will provide convenient access to the valve stem, allowing for the tires to be inflated and deflated as needed. If not, then there may be a hole in the wheel assembly to allow the valve stem to extend from the inner wheel half.
While aircraft wheels are extremely robust, they still require regular maintenance and part replacement to reliably serve an aircraft. At Aerospace Buying, we serve as a premier online distributor of aircraft parts, offering customers competitive pricing and rapid lead-times on ABS wheel sensor parts, wheel bearing components, valve stem products, and other aviation items. As you explore our various offerings, we invite you to request quotes for your comparisons which you may receive through the submission of an RFQ form on our website. Get started on the procurement process today and see how Aerospace Buying can serve as your strategic sourcing partner for all your operational needs.