Antenna Whipping Against the Roof Deflector

This service bulletin addresses the issue of antenna whipping against the roof deflector on a variety of Freightliner trucks. The bulletin covers a wide range of models, including the FLA COE, FLB COE, FLD Conventional, Business Class, FLC 112 Conventional, Century Class Conventional, Argosy COE, Cargo, Columbia, Coronado, Business Class M2, and Cascadia, as well as the 108SD/114SD models. The service bulletin provides detailed information and instructions for resolving this issue, which can include potential damage to the antenna and the roof deflector.

## The Problem of Antenna Whipping: A Freightliner Tale The "Antenna Whipping Against the Roof Deflector" issue, particularly prevalent in Freightliner trucks, refers to a phenomenon where the antenna, often mounted on the cab roof, violently oscillates against the roof deflector. This issue stems from the interaction between wind forces and the antenna's flexible design. As the truck travels at higher speeds, the air flow over the cab roof creates turbulent eddies that can cause the antenna to vibrate and sway. This forceful movement can result in damage to both the antenna itself, including potential breakage, and the roof deflector, leading to scratches, cracks, or even detachment. The problem is amplified in Freightliner trucks due to their distinctive roof design and the relatively long lengths of antennas used for radio communication and other applications. The COE (Cab Over Engine) models, including the FLA, FLB, and Argosy, are particularly susceptible due to their exposed roof position. Additionally, the presence of roof deflectors, while designed to improve fuel efficiency, can actually create a turbulent wake zone that exacerbates the whipping issue. The whipping motion not only impacts the aesthetics of the truck but also presents a safety concern, as a broken antenna could become a projectile in case of severe vibration or detachment. ## Mitigating Antenna Whipping: Freightliner Solutions To address this issue, Freightliner has implemented various solutions, both proactive and reactive. The most common approach is the use of antenna designs featuring a more rigid construction, often employing a thicker base or internal bracing to dampen vibrations. Some manufacturers also offer flexible antennas with a more aerodynamic profile, reducing their susceptibility to wind forces. Additionally, Freightliner has introduced improved roof deflector designs that minimize turbulence and create a smoother airflow over the cab, effectively reducing the force acting on the antenna. Furthermore, Freightliner encourages drivers to regularly inspect their antennas for signs of damage or excessive wear. Keeping the truck in good alignment and maintaining proper tire pressure also contributes to reducing wind resistance and minimizing antenna whipping. While the issue remains a potential challenge for Freightliner truck owners, the proactive solutions and preventative measures put in place demonstrate a commitment to mitigating the problem and ensuring the safety and longevity of their vehicles.