Manufactured Lean in the USA

Wheel Ergonomic Metrics

Ergonomics is much more than a buzzword or theme of the month. Given the workforce demographics, primarily aging and increasingly obese, paying attention to worker safety has never been more important. Hamilton supplies much-needed data for those seeking acceptable solutions in manual material handling, primarily in pushing and pulling. The cost of back injuries is high, and the cost to replace injured workers is escalating as well. Preventing them can start with optimum wheel selection based on Hamilton’s test results.

Startup Force:

This critical ergonomic factor is dependent on load on a given wheel and the wheel type. An often overlooked factor is that of acceleration – how quickly is the one pushing a load going to achieve a desired speed or pace? Hamilton tests all its wheels at a specific acceleration rate that is likely typical for most workers. The advantage of controlling the test criterion is that comparative test results are useful. Also, should results for a specific acceleration rate be desired, Hamilton can accommodate.

Maintain Force:

Once a worker has begun moving a wheeled device, he or she will maintain a certain speed until reaching the desired destination. Some companies have established upper limits on what forces their employees may be exposed to when performing manual material handling tasks. Hamilton’s test results can be used to select compliant wheels. Notice that wheel diameter plays a significant role in these forces – larger wheels are easier to move under load.

Load Distribution:

How much force is applied to the floor by a wheel under load? When this information is important to protect valuable plant floors, Hamilton’s footprint data provides answers. Empirical data collected from numerous tests demonstrates the floor loading under various loads. Generally, softer loads and larger, wider tread wheels spread a given load over a larger surface area, resulting in less force per unit of area applied to the floor.


Essentially this is the amount of floor area covered by the tread of a wheel under a specified load. As one would suspect, softer tread wheels have larger footprints than harder tread wheels, and crown tread wheels have smaller footprints than flat tread wheels. There is some correlation to rolling resistance; larger footprint wheels are generally harder to move under load. As the load increases, resilient tread wheels develop larger footprints. Footprint is the measurement used to calculate load distribution (floor pressure).