Evaluation of rolling resistance in manual wheelchair wheels and casters using drum-based testing.

PURPOSE

Rolling resistance is a drag force that increases the required propulsion force of manual wheelchair users (MWU) and increases the risk of upper extremity pain and injury.

MATERIALS AND METHODS

To understand the influence of different design, environmental, and setup factors on rolling resistance (RR), a series of tests were performed on a range of wheels and casters using a drum-based equipment with the capability to measure RR forces. Independent factors were varied including load, camber, toe, speed, tire pressure, and surface, using ranges anticipated in the community. Combined factor testing of these factors was also completed to evaluate of RR changes due interactions of multiple factors.

RESULTS

A default reference trial was used to verify repeatability throughout the 924 rear wheel trials and 255 caster trials. Toe angle and tire pressure were found to have large and exponential relationships to RR. Tire/caster type and surfaces are significant influencers but have no specific relationship to RR. Load had a direct linear relationship to RR whereas camber and speed had a relatively small impact on RR. Pneumatic tires had lower rolling resistance compared to airless inserts, solid mag wheels and knobby tires. Combined factor testing revealed a linear additive effect of individual factors. Statistical analysis revealed that tire/caster type is a covariate to all of the results and statistical differences ( < 0.01) were found for toe, tire/caster type, tire pressure, surfaces and load.

CONCLUSIONS

Factors act in a cumulative manner to impact RR and need to be monitored in device design, development, issuance, and maintenance.Implications for RehabilitationFirst comprehensive study of MWC RR showing the effects of individual and combined factors.Highlights the direct importance of tire and caster selection.