MHI, in conjunction with Ergoweb, conducted extensive research on the ergonomics of material handling and highlighted the importance of proper cart, wheel, and caster design in reducing worker strain, improving productivity, and minimizing workplace injuries. Wheeled equipment is utilized in nearly every industry. Hospitals transport medications, supplies, and patients using carts, manufacturing facilities rely on mobile process equipment to support lean production, offices use carts for mail and supply distribution, and virtually all manufacturing and distribution centers depend on wheeled equipment throughout their operations. Despite their widespread use, wheeled devices are often taken for granted, and the selection of appropriate carts, wheels, and casters is frequently overlooked.
Careful design of manual pushing and pulling tasks can provide measurable improvements in efficiency and reduce hidden costs associated with poor ergonomics. According to MHI and Ergoweb, ergonomics encompasses much more than health and safety concerns. Although ergonomics is commonly associated with injury prevention, the discipline originally developed from efforts to improve business efficiency and quality. Today, ergonomics addresses productivity, quality, and employee health and safety, all of which have associated costs that can significantly impact organizational performance. Effective ergonomic interventions often increase efficiency by eliminating awkward postures and unnecessary movements, thereby reducing the time and effort required to complete tasks while improving work quality and reducing errors.
MHI and Ergoweb further examined the specific forces involved in manual pushing and turning of industrial carts. Three primary forces combine to resist turning. These include friction within the swivel housing and at the wheel-floor contact point, inertial forces resulting from acceleration during directional changes, and physical interference that may exist between the wheel and floor surface.
When a cart is already in motion and an operator initiates a turn, inertial forces depend on the amount of acceleration applied in the new direction. During fine positioning tasks involving frequent starts and stops, these inertial forces become even more significant because repeated acceleration and deceleration increase the physical demands placed on workers.
Friction between the wheel and floor surface can also substantially increase the force required to maneuver equipment. Friction within poorly maintained or inferior swivel housings further contributes to resistance. Wheel characteristics greatly influence these forces. Smaller-diameter wheels and softer, more compliant wheel materials tend to flatten under load, increasing the contact area between the wheel and floor. This larger contact area causes the wheel to “grip” or “stick” to the floor when pivoting, making turning and positioning more difficult. Conversely, harder wheel materials and larger diameters generally reduce rolling resistance and improve maneuverability.
Manufacturers address these challenges by incorporating caster offset designs. In this configuration, the wheel is positioned laterally from the swivel axis where the caster housing attaches to the equipment. This offset creates a horizontal lever arm that allows a relatively small force applied to the cart to rotate the wheel into alignment with the new direction of travel. Without this offset, the entire piece of equipment would have to be moved in a large arc before the wheel could swivel. Offset caster designs therefore enhance maneuverability and are especially valuable when fine positioning equipment in confined spaces where small adjustments are required.
The differences between four-wheel and six-wheel industrial carts are relatively straightforward. Four-wheel carts provide higher push-pull forces, lower purchase costs, and larger turning radii. Six-wheel carts, however, require lower push-pull forces, track more effectively, offer improved maneuverability, and create a turning point centered on the middle wheels. Selecting the appropriate configuration depends on the intended application and desired balance between maneuverability and cost.
The selection of wheels, casters, and cart configurations has important implications beyond initial purchase price. Excessive friction and poorly designed components increase physical demands on workers, contribute to fatigue, and raise the risk of injury. Additionally, maintenance requirements and equipment longevity should be considered when evaluating material handling equipment. Purchasing decisions based solely on upfront cost often overlook long-term maintenance expenses and productivity losses. Manufacturers such as Topper Industrial emphasize the importance of high-quality caster systems because they believe wheel and caster design directly affect long-term reliability, productivity, and overall cart performance, regardless of whether a four-wheel or six-wheel design is utilized.
Ultimately, ergonomics, equipment design, and workplace safety are closely interconnected. Properly designed carts and material handling systems reduce the physical demands placed on workers and improve productivity, and enhance work quality. By considering ergonomic principles, wheel and caster characteristics, operating environments, and overall system design, organizations can achieve significant long-term benefits in safety, efficiency, and operational performance.
For additional information about this cart design or Topper Industrial’s complete line of material handling solutions, please contact the sales team at sales@topperindustrial.com.
Topper Industrial (www.topperindustrial.com) is a leading manufacturer of material handling equipment. Topper provides lean material handling solutions to the supply chain.
Topper Industrial engineers and design Industrial Carts (Mother Daughter Cart Systems, Quad Steer Carts or Tracking Carts, Specialized Tugger Carts, Transfer Carts with Roller Deck, Static Carts, Rotation Carts, Tilt Carts or Kitting Carts), Industrial Cart Components (Cart Tow Bars, Couplers/ Hitches, Brakes, Etc.), Industrial Containers (Corrugated Steel, Wire Mesh), Pallets, and Lift/Tilt Systems. Topper Industrial designs all products with ergonomics in mind, focusing on ease of use and best positioning of material to get the job done.