The decision to use properly sized wheels often receives little attention until a problem arises. A forged steel wheel that’s only slightly undersized for a specific job will often perform flawlessly for weeks or even months, which masks the problem during initial installation. But undersizing doesn’t just reduce the life of the wheel slightly. It starts a cascade of mechanical issues that can snowball over time, resulting in failure that costs much more than the wheel itself.
The Load Rating Is Not a Suggestion
When designing a wheel, an engineer considers the size, diameter, construction, materials, and hub configuration. All these factors are taken into account to achieve a designated load rating, which is the maximum amount of weight the wheel can bear under specified operating conditions. When the actual operating load is higher than the wheels are engineered to carry even by a little, they’re being asked to perform a job they can’t sustain.
It’s easy to understate the consequences of overloading a wheel assembly. The key difference, however, is that an overstressed wheel may continue to function, but that functionality comes at the cost of increased wear. The problems are cumulative rather than sudden.
What’s Going On Inside the Undersized Wheel
An undersized wheel can’t distribute the workload properly among its components. Instead, the load becomes concentrated in certain spots, especially at the point of contact with the surface the wheel travels over, and at the bearing interface where the load is transferred from the wheel into the bearing and axle shaft.
Inevitably, with repeated use, the wheel can begin to deform at the point of contact with the surface. If the wheel is not made from material tough enough to resist deformation, the point of contact can become flattened or distorted. This not only increases rolling resistance but also places stress on additional points across the wheel’s surface. The material continues to degrade due to cyclical stresses that it was not designed to withstand, resulting in surface fatigue. Eventually, this fatigue can progress to the point where the wheel cracks—especially at points of internal weakness often present in cast materials.
The wear and tear on the wheel itself also puts increased strain on the wheel bearing and axle. These components are rarely designed to compensate for a wheel that is already struggling to maintain its shape under load. As a result, a wheel problem can quickly become an axle or bearing problem.
Why Material is Just As Important as Wheel Size
So, are any wheel made of rubber or polyurethane sufficient for a low-load application?
No. When it comes to load capacity, material is just as critical as size. A wheel with lower-strength material will experience a failure at a lower load than a wheel of similar dimensions made from tougher material. This is also the key reason for distinguishing between cast and forged wheels.
When material is cast, it’s heated to molten form and poured into a mold. This process inevitably leaves behind imperfections, such as voids or areas of inconsistent grain structure, which can compromise the wheel’s structural integrity under load.
Steel is cast into a wheel by pouring molten steel into a mold while a forged steel wheel is formed by heating steel and then shaping it under immense pressure. This more tightly controlled and disciplined manufacturing process results in a denser, more consistent material and can increase a wheel’s ability to hold up under heavy or repeated shock loads close to its maximum rated load, without risking structural integrity failure.
Building A Margin Of Error Into Your Wheel Selection
Properly sizing a wheel isn’t simply matching it to the calculated base load. The best approach is to design in a buffer to accommodate factors like shock loads during operation, uneven weight distribution caused by an imbalanced load, and the general imperfections of real-world conditions.
A wheel closely matched to the peak load without a reserve provides very little protection from an unanticipated load spike. At Rockett Inc., we partner with our customers to ensure that the wheels are specified and sized according to the actual operating conditions of their equipment, not just the static load chart on paper.
Proper Wheel Sizing Protects the Entire Assembly
A proper forged steel wheel that’s suited to the load conditions in your facility can prevent costly equipment breakdowns, reduce downtime, and protect you from the collateral damage associated with failed or damaged wheels. We’re happy to review your operating conditions and help you specify the correct wheels for your application. Contact us today to start the conversation.
FAQs
- What is a forged steel wheel?
A forged steel wheel is a wheel manufactured by shaping high-strength steel under significant heat and pressure. This forging process creates a dense, durable wheel designed to withstand heavy loads, impacts, and demanding operating conditions.
- What are the advantages of forged steel wheels?
Forged steel wheels offer excellent strength, durability, impact resistance, and load-bearing capacity. They are particularly suitable for commercial vehicles, heavy-duty equipment, industrial applications, and other environments where wheel reliability is critical.
- How is a forged steel wheel different from a cast wheel?
Forged steel wheels are formed through a forging process that compresses and shapes the steel, generally producing a strong and dense material structure. Cast wheels are produced by pouring molten material into a mold. The best option depends on factors such as vehicle type, load requirements, operating conditions, and cost.
- Where are forged steel wheels commonly used?
Forged steel cart wheels are commonly used on heavy-duty carts, material handling equipment, industrial carts, platform carts, and other applications where wheels must withstand heavy loads, repeated use, and demanding operating conditions.
- How do I choose the right forged steel wheel?
Consider the vehicle or equipment type, wheel size, load rating, mounting configuration, material specifications, operating environment, and applicable safety standards. Always verify compatibility with the vehicle or equipment manufacturer’s specifications.