A normal wheelchair provides mobility to a handicapped person over flat land. But when it comes to staircases they'll always have to depend on others to get over such obstacles. Although there are places where we can find disabled friendly arrangements, it's impossible to provide it everywhere.
So we have come up with a wheelchair design which has the ability to climb stairs, footpath kerbs etc;
Our design consists of three main components viz. the wheel chair and two other components called outer and inner legs.
The mechanism will be housed in the space available under the chair i.e. between the wheels.
On approaching any staircase the mechanism can be actuated by a lever. On actuation the outer leg of the mechanism will descends and pushes against the ground. Thus pushing the wheelchair up to the level of the first step. After this the inner set of legs move forward and places itself on the first step (Illustration 1).
Next the wheel chair slides forward and is now resting on the inner set of legs on the first step. In the next set of motions, the outer set of legs lifts upwards and moves forward and then again descends down on the first step thus pushing the rest of the wheel chair up onto the level of the second step (Illustrations 2 & 3).
And then cyclically these set of movements repeat(i.e. inner leg moving forward). These movements continue until the wheel chair reaches the top of the stairs and the mechanism can be deactivated and the wheel chair can move with its wheels as usual.
These set of motions will be powered by either hand cranking by the wheel chair occupant or an electric motor onboard the wheel chair. The circular motion generated by the crank or the motor will be converted into these sequence of cyclically repeating motions (i.e. that of inner and outer legs), by using various gears and other mechanisms (ex:- Rack and pinion gears, chain drives etc;).
During the motion of outer leg pushing up the wheel chair up onto the next step. If the power from the cranking or the motor is stopped . Due to the weight of the wheel chair,it descends back onto the lower step. This can be avoided by incorporating a pneumatic cylinder-piston mechanism in the outer leg. So as the wheel chair raises, gas fills in to the cylinder through a valve, thus acting as a support during the ascent.
Manufacurability:- The major components involved here are-1)The wheelchair – Is easily manufacturable. 2) The inner, outer legs and the slider- Will be made of steel or aluminium and can be manufactured by simple machining operations. 3) The gears and other components - are easily manufactured.
Consider the ease of manufacturability of this product. It can be easily marketed at a low cost. Also since it relieves wheelchair bound people from depending on others, this low cost product can be an attractive proposition.