A recently published paper on reducing back injury risks, “Biomechanically-Determined Guidelines for Occupational Pushing and Pulling”, suggests that “the manual materials handling burden has shifted towards pushing and pulling”; presumably, away from lifting and carrying. Manual material handling using carts is a prime example of an occupational push and pull task. Managing the risk associated with pushing, pulling and maneuvering carts in the workplace is a critical component of an industrial ergonomics program.
As most facilities or organizations have fleets of carts, a systematic approach is useful in managing and reducing the risks associated with cart handling. While such a system will vary to suit the idiosyncrasies of different operations, there are some common components to these ergonomics cart management programs.
Cart Ergonomics Best Practices
Best Practice #1 – Measure Cart Operating Forces Throughout the Life of the Cart
The most basic component of a cart management program is the ability to accurately and consistently measure the forces required to move carts during typical usage. It is crucial to then compare those forces to reference standards, such as the Liberty Mutual Tables, to evaluate the acceptability of the required forces. It is important to note that this force measurement should be repeated at intervals for carts in service to ensure that the required operating forces remain at acceptable levels. Experience with these periodic measurements will also help to guide decisions as to whether the maintenance interval may be lengthened or shortened. It can also identify whether a particular type of cart requires more or less frequent reassessment.
Best Practice #2 – Design for Cart Performance at Acquisition
Specifying cart performance at the time of acquisition is a second major component of a good program for managing cart handling ergonomics. Why bring problems in with new carts when acceptable force levels can be made part of the purchase and cart design specification? This includes assessing specific cart design and components of the cart for their ergonomic benefits or detriments. In particular, the cart’s caster wheels can make a significant impact on push/pull forces. So, upfront cart design, engineering improvements and investment in the right casters for the environment and usage can lower push/pull forces and achieve reduced maintenance requirements.
An important part of specifying new carts’ performance is to be aware of the environment in which they are used. For example, are they likely to be used on unpaved surfaces or paved surfaces with cracks or litter? This information is critical to selecting the appropriate casters.
To find out more about how casters can affect your carts in manual material handling tasks, you may want to read some recent articles from Darcor:
- Designing Wheeled Equipment: Purchasing Considerations to Achieve Long-Term Ergonomic and Economic Success
- 5 Questions to Ask when Choosing a Caster
- How a High Quality Caster Can Reduce Workplace Overexertion Costs
Best Practice #3 – Track and Monitor Each Cart in Service
A third component is the ability to track each cart in service, beginning with the characterization of push, pull and maneuvering forces when it is first put into service and subsequent monitoring to ensure that its operating force requirements remain within acceptable limits. Carts whose performance degrades over time require servicing, for example cleaning debris from casters, replacing worn or damaged casters, etc. Although most good quality casters have sealed bearings, others may not and may require lubrication as well.
Effective Industrial Ergonomics Cart Management Program to Reduce Risk of Injury
By implementing industrial ergonomics best practices for cart management, organizations can benefit by lowering risk of back injury and often will experience increased operational efficiency. To learn more about the benefits of industrial ergonomics programs that reduce risks when pushing, pulling and maneuvering carts, download the Guide to Workplace Ergonomics.
Tom Albin PhD is a licensed professional engineer (PE) and a certified professional ergonomist (CPE). He holds a PhD from the Technical University of Delft in the Netherlands. He is a Fellow of the Human Factors and Ergonomics Society.
Tom has extensive experience as a researcher, corporate ergonomist, and product developer. In addition, he has been active in the US and International Standards community. He is accredited as a US expert to several International Standards Organization working groups and is Vice-Convenor of the ISO committee revising the standards for input devices and workstation layout/postures. He chaired the committee that revised and published the American National Standard ANSI/HFES 100-2007 Human Factors Engineering of Computer Workstations and currently co-chairs the committee working on a new revision of that standard.
