Patent attributes
Apparatus and associated methods relate to a wheelchair power assist device configured to switch a motorized friction roller between engaged and disengaged modes with a wheelchair wheel, based on an engagement actuator configured to move the friction roller relative to an attachment member removably secured to the wheelchair. The friction roller may be operably coupled with an engagement member configured to move relative to the attachment member. The engagement member may be moved by an extendable and retractable actuator shaft coupled with the attachment member. A manual wheelchair may be converted to a powered wheelchair using a motorized friction roller for each wheelchair wheel. A plurality of power assist devices may be configured to position a respective plurality of friction rollers to leave an open space behind the wheelchair seating area, advantageously permitting the power assist devices to remain attached to a foldable wheelchair in either folded or unfolded configurations.