The Effects of a Selected Wheel Design and Caster Fixture Design on Pushing Force When Pushing Four Wheeled Industrial Carts

Abstract

Manual material handlings tasks, many of which require pushing and pulling are common in almost all industrial and service sector environments. These tasks expose workers to musculoskeletal stresses as well as other related slipping and tripping hazards. The company sponsor of this study sought to lower the risk of injury from manually pushing and pulling carts. The company wanted to evaluate a newer style of split wheel and also an offset pivot dual orbital caster, which the manufacturer states will reduce pushing and pulling force. A total of eight participants (4 male, 4 female) were included in the study. Participants were required to push a four-wheeled cart 16 times for 10 meters. The cart was pushed 8 times with a total gross weight of 250 lbs (113.4 kgs) and another 8 times with 750 lbs (340.2 kgs). Only the rear wheels could swivel and were tested both perpendicular and inline to the direction of travel. The split wheel was compared to a single wheel and the dual orbital caster was compared to a standard style of caster. All possible combinations were tested. Applied force was measured and analysis was conducted on instantaneous peak force. Results showed that the caster design did not significantly affect the initial applied force. However, the dual orbital caster was consistent in the amount of applied force when the wheels were perpendicular or aligned to the direction of travel. The dual orbital caster resulted in lower initial applied forces when used together with the single wheel design. In addition, the dual orbital caster showed marked decrease in the applied push force when wheels where positioned perpendicular to the direction of travel compared to the standard caster. These results strengthen the recommendation for the company to invest in the dual orbital - also referred to offset pivot caster. Secondly, though the wheel type significantly affected the applied force the mean applied force difference between the two wheel types was not practically significant enough to warrant a change of the wheel type in the company.