Alternate Propulsion Mechanism
for a wheelchair

This project deals with the design and analysis of a mechanism for a wheelchair which is propelled using the lever with our hands. The mechanism is placed on both sides of the wheelchair and is actuated independently with a lever on each side. The lever which is pivoted about an axis to the sides with help of bearing has to be pushed and pulled continuously to propel the wheelchair. Two sprockets and the lever of the mechanism are constrained to rotate together mounted over a bearing attached to the frame of the wheelchair on both sides. These two sprockets are each meshed with a freewheel which is coaxially placed with the axis of rotation of wheels of the wheelchair through cycle chains. One of the sprocket and freewheel on both sides is meshed in cross-over chain configuration. This enables the wheelchair to propel forward in both push and pull strokes of the lever.

The wheelchair with such a mechanism is affordable and simple in design. It uses only bicycle components and can thus be easily repaired in nearby bicycle shops. By varying the sprocket and freewheel size, we can obtain different performances for the wheelchair. The average speed attained is 2.12 m/s and the levers can function like gears as discussed above. The aim of the work to design a simple mechanism to improve performance and affordability of the wheelchair was thus succeeded