Fire truck feedback leads to new suspension
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Link Mfg. recently released its new RespondAir heavy-duty rear air suspension system (rated for 30,000-35,000-lb. capacities) specifically designed for fire and rescue vehicle applications. The company said it designed the suspension with fire and rescue in mind, particularly after receiving feedback regarding traditional suspensions’ maintenance, stability and control, and ride quality from its voice-of-customer survey.
“Through extensive voice-of-customer research with fire departments and OEMs, we identified critical needs around maintenance, stability, and equipment protection,” said Mark Molitor, senior product manager for Link Manufacturing. “RespondAir represents Link’s 26-plus-year commitment to those industry needs with a purpose-built solution that eliminates common pain points while delivering superior performance in emergency response situations.”
For example, Link’s study found that respondents rated maintenance as their number-one concern (with 71% ranking it as ‘very important). Respondents reported current suspensions had problems with the bushings, with fire departments shouldering high costs when bushings failed, meaning entire suspension systems needed to be replaced. Some respondents also reported premature bushing wear, and others noted that some suspension manufacturers would use undersized bushings, and then sell heavy-duty or severe-duty replacements.
To address this feedback, Link’s RespondAir heavy-duty system uses larger, more durable rubber bushings, the company said. Their increased surface area reduces component stress and lowers maintenance requirements, Link said, while the system’s weld-on axle brackets (instead of U-bolt connections) also offer longer-term reliability. Respond-Air also uses permanently assembled lower control arms for greater durability, and its non-torque-reactive design works to reduce overall stress on the suspension.
While maintenance concerns ranked first in Link’s study, overall stability came in second in terms of customer importance (with 66% of respondents rating stability as ‘very important). Respondents also noted that track bar designs created ‘tail wagging’ for trucks, with large aerial apparatus’ particularly contributing to the phenomenon and causing safety concerns and increased driver fatigue. To combat this, Link said the Respond-Air system uses a V-Rod configuration for lateral stability and reduced tail swing. Here, the cast steel components and seamless tubing add to the system’s overall durability, while the lower control arms and V-Rod combat the higher center of gravity in fire trucks, minimizing the truck body’s movements during braking and acceleration.
Additionally, users’ third-most important concern was ride quality, with stations and dealers stating that poor ride quality could damage equipment on a fire truck, such as breaking ladders, while operators themselves said they experienced excessive bouncing and jarring. To make travel smoother, Link added integrated soft air springs to the RespondAir and used larger volume air springs to absorb road impacts, including full steel mounting plates to protect the air spring pistons. The company also used heavy-duty shock absorbers to control jounce travel and added Link’s 500 Series dual height control valves for higher flow rates and optimal leveling.
Finally, RespondAir’s higher 30-35k capacity came from customers’ complaints that manufacturers were not delivering higher-capacity suspensions to suit their needs. This helped guide Link in designing the RespondAir specifically for 30-35k-lb. capacity single-axle and 60-70k-lb. capacity tandem axle vehicles. Other features specifically for fire trucks include the rapid air-dump function to help trucks fit in stations with lower garage clearance, the company’s Link-KOAT self-healing metal treatment to protect against corrosion and extreme environments, and how the suspension system can be integrated with both Meritor and Dana axles used in fire trucks.
Link is backing the RespondAir heavy-duty suspension system with warranty coverage on structural components and wear components. The system will be available through OEM partners in late 2025.
About the Author
Alex Keenan
Alex Keenan is an Associate Editor for Fleet Maintenance magazine. She has written on a variety of topics for the past several years and recently joined the transportation industry, reviewing content covering technician challenges and breaking industry news. She holds a bachelor's degree in English from Colorado State University in Fort Collins, Colorado.