Non-metallic cylinders reduce maintenance needs and weight in heavy trucking equipment.

Over the past several years, Polygon Company has designed custom composite housings for pneumatic cylinders in fifth-wheel coupling assemblies by Fontaine Fifth Wheel.


Fontaine Fifth Wheel is the world’s largest dedicated fifth wheel manufacturer and innovator of the only self-adjusting fifth wheel lock in the industry. Fontaine is also home to the largest research and development facility in the world focused exclusively on fifth wheel coupling technology. It was this dedication to innovation that led the development team at Fontaine to consider non-metallic options for the pneumatic cylinders in their fifth-wheel assemblies. The heavy-duty truck market is a rugged application that can expose air cylinders to excessive moisture and contaminants. Standard metallic cylinders can corrode over time and limit the ability of the air cylinder to function properly, shortening the useful life of a pneumatic cylinder. Both on and off the road there are increased chances of foreign objects coming in contact with the cylinders and damaging the cylinder housing, and when standard metallic housings become dented, it usually renders the cylinder inoperable.


Fontaine turned to Polygon for a composite pneumatic cylinder that would resist corrosion from salt, moisture, and debris on the roads, unlike metal components. What’s more, unlike metallic cylinders that can dent and thus prevent the piston’s mechanical action as a result of simple impacts like loose rocks in the road, composite cylinders are strong and hold their shape even under impact. Consequently, Polygon’s composite cylinder solution reduced maintenance needs overall—especially instances of emergency maintenance on the road. Finally, the composite cylinder reduced weight in the fifth-wheel assembly over fully metallic components.


Since its introduction several years ago, the fully-customized composite solution that Polygon delivered to Fontaine through collaboration between both companies’ engineering teams has consistently met Fontaine’s and end users’ needs. Recently, the teams have once again begun collaboration on a next-generation redesign, continuing the companies’ partnership towards greater innovation in the industry through the newest generations of Fontaine’s products.

Says Engineering Manager Shane Wolfe: “The previous problems related to corrosion within air cylinders have been eliminated with the composite housing, stainless, and aluminum components. The composite housing of the Polygon pneumatic cylinder is more suitable to retain its shape when contacted by foreign objects and preserve operability, extending the product life of cylinders. Also, in the competitive truck market where vehicle weight reduction is always a project on the table, composite cylinders reduce overall fifth wheel assembly weight. We can now offer them to truck manufacturers as a weight reducing option.”


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