Abstract
The purpose of this study was to compare the traditional large metal waste carts currently in use in industry to a plastic waste cart with the same load capacity. This was done through initial pull force studies using a dynamometer and biomechanical evaluations of male industrial workers. The initial pull force study involved using a hand force dynamometer to measure the minimum initial pull force needed to move both the metal and plastic carts. Five different metal and three different plastic carts were tested this way on smooth concrete and rough asphalt surfaces, with switching of the wheels between the plastic and metal carts, with larger diameter wheels, and with varying loads inside the carts (O kg to 454 kg). The results showed a significant decrease in the required pull force with the plastic cart on both a smooth concrete (p=0.0001) and on a rough asphalt (p=0.0001) surface. The material of the cart and of the wheel on the plastic cart proved to be significant (both p=0.0001). However, the wheel diameter did not prove to be significant (p=O. 1039). The biomechanical study on industry workers also showed a significant reduction in the required pull force (P=0.0001). The study shows that a safe load limit for a large four-wheel cart is dependent on cart weight (empty), wheel bearings, and wheel diameter. Since all large fourwheel carts do not have the same cart weight (empty), wheel bearings, and wheel diameter, a safe load limit should not be established for all four-wheel carts. Rather a safe load limit would need to be created for each particular four-wheel cart. This study concludes that replacing the traditional metal waste carts with the lighter plastic carts would be extremely rough asphalt, where the carts are normally pushed and pulled, it takes twice as much force to move the metal carts as it does a plastic cart carrying the same load. This means by switching to the plastic carts workers will be reducing the amount of pull force exerted daily by 50%. This should lead to a reduction in push/pull related injuries and a savings to the company.
Abell, David Wayne (1997). Biomechanical analysis of transporting loads with a large four-wheel cart. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1997 -THESIS -A24.