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

Abstract

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 (p < 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 Rehabilitation

• First comprehensive study of MWC RR showing the effects of individual and combined factors.

• Highlights the direct importance of tire and caster selection

Keywords:

• Wheelchair
• friction
• propulsion

Acknowledgments

Thank you to the many individuals who assisted in the development of the rolling resistance drum-based testing equipment and those involved with conducting testing. First, to the co-ops who assisted with design and development of the equipment. London Lee and Mendel Marcus worked extensively on the design and fabrication of the equipment, Travis Henderson worked on the setup and calibration of this equipment, and Holly Wilson-Jene completed a large amount of product testing. Next, for the administrative assistance with purchasing of components and many other details related to this study and to the clinicians and providers for their input to this research. And a special thank you to the Human Engineering Research Laboratories (HERL) for their significant contributions to this development project including the support of many individuals at HERL and their facilities to fabricate and build equipment utilized in this research.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

Thank you also to the ISWP-SWG, who has provided significant support, input, advice and guidance from the inception to completion of this research, all of which are greatly appreciated. There were many grants supporting this research work and paper, including the following: Integrative Graduate Education and Research Traineeship award number IGERT 1144584 from the National Science Foundation, Improving Health and Function Through Use of Performance Standards in Wheelchair Selection Grant # 90REGE0001-02-00, and U.S. Agency for International Development through Agreement Nos. APC-GM-0068, SPANS-037, APC-GM-0107, and FY19-A01-6024. This project was supported in part by the National Institutes of Health through Grant Number UL1-TR-001857.