As a hub axle supplier who’s spent the last 12 years designing, manufacturing, and sourcing heavy-duty and light-duty hub components for everything from agricultural tractors to semi-trailers, I get asked a lot of unexpected questions. But none has stuck with me quite like the one I got last month from a small fleet manager in Iowa: “Are hub axles bad for the environment?” It caught me off guard at first—for years, my work has been focused on making parts that keep vehicles moving safely, efficiently, and affordably, with environmental performance a close second to durability. But after that conversation, I dug into the research, combed through our own manufacturing data, and even looped in the environmental team at our metal casting partner, and now I can tell you: the answer isn’t a simple yes or no. It’s a story about tradeoffs, intentional design, and how even a small, overlooked component like a hub axle can have outsized environmental impacts—for better or worse.
Let’s start with the baseline: what actually is a hub axle, and why does its environmental footprint matter? For anyone who’s not in the trucking or construction space, a hub axle is the central assembly that connects a vehicle’s wheels to its chassis, handling load distribution, torque, and steering. It’s made up of a few key parts: the axle shaft itself, the hub (the part that holds the wheel bearing and attaches to the wheel), and related components like fasteners or adapters. For our company, that means manufacturing everything from rough-cast trailer wheel hubs to precision-machined drive shafts, plus the flanges and pins that hold it all together. Over the years, we’ve used a mix of materials—mostly steel, some aluminum for light-duty applications, and even a small amount of composite for specialty parts—but steel is still the workhorse, making up 85% of the hub axles and components we supply today. That material choice is at the heart of both the environmental challenges and the solutions.
First, let’s talk about the environmental impacts that are baked into the hub axle’s lifecycle, starting with raw material extraction and manufacturing. Steel production, as anyone who’s followed climate news knows, is one of the most carbon-intensive industrial processes on the planet. Globally, steel manufacturing accounts for around 7% of total greenhouse gas emissions, according to the International Energy Agency (IEA), and hub axles are no exception. When we source raw steel billet to machine into an axle or cast into a trailer wheel hub, that process starts with mining iron ore, which requires energy (and often deforestation or habitat disruption at mine sites) to extract, then smelting the ore in blast furnaces that run on coking coal. Our own data shows that for every ton of steel hub component we produce, roughly 2.2 tons of CO₂ are emitted during the smelting and primary processing stage—before we even get to our shop floor, where machining, casting, and finishing add another 0.3 tons of CO₂ per ton of product.
But manufacturing isn’t the only part of the lifecycle to consider. Hub axles are heavy—even a standard semi-trailer hub axle weighs between 150 and 200 pounds, and for heavy-duty construction equipment, they can hit 500 pounds or more. That weight adds up for vehicle efficiency. Every extra pound on a semi-trailer reduces its fuel efficiency by roughly 0.05% per 100 pounds, according to the American Trucking Associations (ATA). Multiply that by a fleet of 100 trailers, each driving 120,000 miles a year, and that’s thousands of gallons of extra diesel burned annually—translating directly to more tailpipe emissions, nitrogen oxide pollution, and particulate matter. For over-the-road trucking, which accounts for 24% of all transportation emissions in the U.S., that’s a meaningful impact.
Then there’s the end-of-life stage. Hub axles are designed to last for decades, but when they reach the end of their service life, what happens? Steel hub components are 100% recyclable, right? In theory, yes—but in practice, that’s not always the case. Older hub axles, especially those made before the 1990s, often have cadmium or zinc plating to prevent corrosion, and mixing those plated parts with standard steel scrap can contaminate entire batches of recycled steel. We’ve seen that firsthand: a few years back, a scrap yard we worked with rejected a load of 200 old trailer hub shafts because they had leftover heavy metal plating, forcing the yard to process them as hazardous waste instead of recycling them. That adds to landfill burden and creates toxic leachate risks for groundwater.
But here’s the thing: the environmental story of hub axles isn’t all negative. Over the last 8 years, our company has made intentional, data-driven changes to our product line and manufacturing processes that have cut the carbon footprint of our hub axle components by 32%—and that’s not unusual for the industry. Let’s break down those improvements, which start with material and design choices. A big one is moving from heavy, single-piece steel hubs to modular, lighter designs that use high-strength low-alloy (HSLA) steel. HSLA is 20% stronger than standard carbon steel, so we can make hub shafts that are thinner, lighter, and use 15% less material per unit without sacrificing durability. That lighter weight directly improves vehicle fuel efficiency: our R&D team calculated that a fleet switching from standard steel trailer hubs to our HSLA hubs saves 1.2 gallons of diesel per 1,000 miles, which adds up to over 140 gallons per trailer annually for long-haul routes. We’ve also optimized our component design to reduce excess material: instead of machining a whole shaft from a solid steel bar, we now design parts that can be cast or forged with near-net shapes, cutting material waste by 28% in our manufacturing process. That not only reduces scrap going to landfills but also cuts the energy needed to machine parts.
Another key improvement is in manufacturing energy. When I started in this industry, most metalworking shops ran on grid power that was 50% fossil fuel, but that’s no longer the case for us. In 2018, we installed a 1.2 MW solar array on our main production facility, and we now source 82% of our electricity from on-site solar and wind power purchases through our local utility. We’ve also upgraded our machining equipment to run on variable-frequency drives, which adjust power use based on the task instead of running at full capacity 24/7, cutting energy use per part by 19%. Even our finishing process has changed: we phased out cadmium plating in 2017, switching to a trivalent chromium coating that’s 90% less toxic and 20% more durable, extending the service life of our hubs by 30% and reducing the risk of hazardous waste at end-of-life. We’ve also invested in a closed-loop wastewater system that recycles 95% of the water used in our plating and machining processes, cutting our water use by 1.2 million gallons annually.
But maybe the most impactful environmental win for hub axles comes from the circular economy, which is something we’ve prioritized since 2020. Our company now operates a take-back program for old hub axle components, working with scrap yards and fleet managers to collect used hubs and shafts instead of letting them end up in landfills. Once collected, we process them to remove any remaining plating or contaminants, then send them back to our steel supplier to be melted down and used as raw material for new parts. Last year, we recycled over 1,200 tons of hub components through this program—enough to make over 8,000 new trailer wheel hubs. The steel we get from recycled scrap has a carbon footprint that’s 75% lower than steel made from virgin ore, so that cuts the emissions of our new parts dramatically. We also work with a third-party metal testing lab to ensure that all recycled steel we use meets the same strength and durability standards as virgin steel, so our customers never have to trade performance for sustainability.
Of course, there are still gaps. For light-duty hub axles, which are used on passenger cars and small SUVs, the environmental tradeoffs are a bit different. Those parts are often made of aluminum, which is lighter than steel and improves fuel efficiency, but aluminum production is even more carbon-intensive than steel—roughly twice as much CO₂ per ton, when using virgin bauxite. That’s why for light-duty applications, we’ve started using recycled aluminum for 65% of our hub components, which cuts the carbon footprint of those parts by 80% compared to virgin aluminum. We’re also experimenting with hybrid designs for electric vehicle (EV) hub axles, which need to handle higher torque and weight from heavy EV batteries. Our team is working on a design that uses a lightweight aluminum hub with a steel insert for durability, balancing the need for low weight to maximize EV range with the strength to handle heavy loads. Early testing shows that this design could extend EV range by up to 2.5% per vehicle, which is a small but meaningful gain as the EV fleet grows.
What about the future? The biggest environmental challenge for hub axles, and for the entire transport sector, is the transition to zero-emission vehicles and circular manufacturing. Right now, even the most efficient hub axle still has a footprint tied to primary steel production, but advances in green steel—made using hydrogen instead of coal in smelting—could change that. Our steel supplier is part of a consortium testing green steel production at a pilot plant in the U.S., and we plan to switch 40% of our steel sourcing to green steel by 2028, which would cut our hub axle emissions by an additional 40%. We’re also investing in additive manufacturing (3D printing) for small hub components, like flange parts and machined pins construction machinery parts, which can reduce material waste by up to 90% compared to traditional machining from solid bar stock. Early tests of 3D-printed pins show they meet the same load and durability standards as machined parts, so this could be a game-changer for small, high-precision components that were once a big source of scrap.
Another area we’re focused on is extending the service life of hub axles through better design and maintenance. A hub axle that lasts 10 years instead of 7 cuts the total number of parts produced, which reduces raw material extraction and manufacturing emissions. That’s why we offer a 5-year warranty on all our hub axles, and we work with fleet managers to provide regular inspection and maintenance guidelines—like checking wheel bearings to reduce friction, which not only improves fuel efficiency but also prevents premature wear that leads to part replacement. We’ve found that fleets that follow our maintenance guidelines reduce their hub axle replacement rate by 22%, which translates to less waste and lower overall emissions over time.
At the end of the day, the environmental impacts of hub axles aren’t inevitable. They’re the result of choices we make: what materials we use, how we manufacture them, how we design parts to last, and how we handle them at the end of their life. As a supplier, my job isn’t just to sell parts—it’s to help customers make choices that reduce their environmental footprint without sacrificing safety, reliability, or cost.
If you’re a fleet manager, equipment manufacturer, or part of a transport business looking to source hub axles that balance performance, durability, and sustainability, we’d welcome the chance to talk. We can walk you through our current product line, our take-back program, and how our custom designs can help your fleet save fuel and reduce waste. Whether you’re looking for standard trailer wheel hubs cast hub, precision-machined drive shafts, or custom flange parts tailored to your application, we can work with you to find a solution that fits your needs.
References
- International Energy Agency (IEA). (2023). Steel and CO2 Emissions: Global Status and Roadmap for Decarbonization. IEA Publications, Paris.
- American Trucking Associations (ATA). (2022). Fuel Efficiency Improvements for Heavy-Duty Commercial Vehicles. ATA Research Foundation, Alexandria, VA.
- U.S. Environmental Protection Agency (EPA). (2021). Metal Finishing and Plating Sector: Pollution Prevention Opportunities. EPA Office of Water, Washington, D.C.
- World Steel Association. (2023). Recycling Rates of Steel Products: Global Trends and Opportunities. World Steel Association, Brussels.
- International Aluminium Institute (IAI). (2022). Life Cycle Assessment of Primary vs. Recycled Aluminium. IAI Publications, London.
