Why do some wheels in the same batch wear out sooner while others remain intact? The issue may lie in the frame rigidity beyond “load distribution.”
Why do some casters in the same batch fail sooner while others remain intact? The issue may lie in the frame’s rigidity beyond “load distribution.”
Industrial equipment is equipped with four or even six casters, leading many to naturally assume that the weight of the equipment will be evenly distributed across each wheel.
However, in practical use, a phenomenon often occurs: among the same set of casters on the same piece of equipment, used for the same duration, one or two may show obvious wear, while the others remain in good condition.
At this point, in addition to checking whether the equipment is overloaded, there is another easily overlooked issue—the rigidity of the equipment frame itself.
The phrase “all four wheels touching the ground simultaneously” does not mean that all four casters are always bearing approximately equal loads.
1. Wheel bearing is not just a simple division
During the equipment design phase, the total weight of the machine is often estimated first, followed by load-bearing selection based on the number of casters.
This method can serve as a fundamental reference, but real-world equipment is not an absolutely rigid geometric body.
The frame consists of profiles, plates, welded structures, and various equipment components. As the load varies, the structure may undergo a certain degree of elastic deformation.
If the equipment base lacks sufficient rigidity, certain casters may bear more load while others experience relatively lower actual forces.
Therefore, “equipped with four wheels” does not inherently mean “all four wheels work equally.”.
2. Why does the empty truck work fine, but problems arise after loading?
This is an important clue for determining the rigidity of the frame.
The weight is relatively light when the equipment is unloaded, and the deformation of the frame is not obvious. All four casters appear to be in normal contact with the ground.
After loading, the frame is subjected to greater forces, and the originally minor structural differences may be amplified.
After a slight subsidence occurs at a certain corner, the caster at that position may bear more load; at the same time, another caster may even experience a lighter grounding condition.
Thus, a very strange phenomenon will arise:
No abnormalities are noticeable when stationary, but during actual loading and operation, one of the casters tends to malfunction more frequently.
3. The long chassis is particularly noteworthy for its “mid-span deformation.”
For materials trucks, tooling trucks, and large equipment bases with longer body lengths, the issue may not necessarily occur at the four corners.
If the structural span is large, the middle region may exhibit certain deflection under load.
This is also why some large mobile devices adopt six or even more wheel sets.
However, increasing the number of casters does not automatically solve the problem.
If the frame structure and wheel arrangement are not properly coordinated, certain casters may bear the primary load while others contribute minimally in practice.
The more wheels there are, the more attention must be paid to the relationship between the equipment structure and the supporting points.
4. Twisting of the frame may also cause the wheels to “hang and work”
Another scenario arises from manufacturing and assembly.
After processing, if the several positions where the casters are installed are not maintained in a reasonable relative state, a large welded frame may experience slight distortion.
After being placed on the ground, some casters have sufficient contact, while others do not have ideal contact.
Pushing with your hands when the car is empty may not feel obvious.
But as the load increases, the differences in force between each support point may be further reflected.
Therefore, before installing casters on large mobile devices, it is not only necessary to accurately locate the holes on the bottom plate of the casters, but also to check the overall relationship between the installation surfaces of several casters.
5. Why is the problem of ‘diagonal two’ always more serious?
If the wheels on the device often show significant diagonal differences, it is worth checking whether the frame is in a twisted state.
For example, if one set of diagonal casters is significantly worn while the other set is relatively light, this may indicate that the actual force on each support point is not consistent.
Of course, the cause cannot be directly determined based solely on the wear pattern.
The ground, equipment center of gravity, operating route, and installation status all need to be checked together.
But the obvious inconsistency between the wheels is already a signal worth continuing to track.
6. Increasing the number of casters does not necessarily mean improving effective load-bearing capacity
This is a common misconception in device design.
Four is not enough, then increase to six; If six were still worried, it increased to eight.
But if the frame itself cannot provide reasonable support for these casters, the additional wheels may not be able to share the load as expected.
Especially for fixed multi wheel structures, overall consideration should be given to equipment length, chassis rigidity, and actual ground conditions.
Otherwise, the theoretical “multiple rounds of sharing” may differ from the actual situation on site.
7. How to conduct preliminary investigation on site?
You can start with a few simple phenomena.
Observe whether there is a significant change in the grounding status of each wheel when the equipment is unloaded and fully loaded;
Check if there are any abnormal differences in the degree of wear on the wheel surface of different casters;
Observe whether there is any obvious bending or twisting of the equipment chassis;
If the fixed position casters are damaged in advance, the corresponding frame structure at that position can be further inspected.
When necessary, the actual loading status of the equipment should also be included in the inspection, rather than just checking an empty vehicle.
Write it at the end
Many abnormalities in the wheels may not necessarily come from the wheels themselves.
The amount of function that a caster can undertake depends not only on the weight of the equipment, but also on the center of gravity of the equipment, the rigidity of the frame, the installation status, and the relationship between each support point.
Therefore, when there is a significant difference in the lifespan of the casters on the same device, it is advisable to shift your gaze upwards from the wheels.
Casters are the connection points between equipment and the ground, and the frame determines how the load arrives at these connection points.
Choosing the right wheels is crucial, ensuring that each wheel operates in a reasonable state is equally important.
For more information of industrial Casters, please feel free to contact GLOBE Team!
Post time: Sep-24-2026
