4. PREAMBLE TO THE DESCRIPTION
The following specification describes the invention:
Accordingly, the present invention is a retrofit/mechanism/devicefor a personal wheel chair to enable it to produce high torque and capable of differential driving. Differently -abled person finds it difficult to climb a slope or maneuver in an irregular terrain with a conventional wheelchair. To overcome this problem, the proposed high torque and differential drive mechanism in TurnNTorq will help the differently-abled person to easily climb/maneuver in a slope or irregular terrains. The general need of such a retrofit is depicted using the Figs. 1 & 2. The solution is identified by the inventors, and "TurnNTorq" is proposed.
5. DESCRIPTION OF THE INVENTION
a. Fields of invention:Mechatronics; Automation; Mechanism; Differently-abled wheel chair
b. Background of the invention:
The hand powered conventional wheelchair users face a major problem of less torque when they are moving on the slope or grassy surfaces as shown in Fig.l. For an instance, if the applied torque is less than the required torque then the wheelchair will move backwards which is of no use.


Another problem faced by the differently-abled persons who are using the hand powered conventional wheelchair is easiness to take turn in narrow path. Figure 2 showshowit is difficult to take a turn in narrow path.



The problems associated with the hand powered conventional wheel chairs are listed below:
> Struck in grassy surfaces
> Need help to move or to climb the slope
> Hands get tired
> Difficult to turn in a narrow space.
In order to overcome the above stated problems, one stop solution TurnNTorq device/mechanism is proposed.
Prior art
1. Amos, G. Winter V., et al. "Wheelchair with lever drivetrain." U.S. Patent Application No. 13/356,585.
2. Kuiken, Todd A. "Manually operable standing wheelchair." U.S. Patent No. 7,165,778. 23 Jan. 2007.
3. Cooper, Rory A. "Intelligent control of power wheelchairs." IEEE Engineering in Medicine and Biology magazine 14.4 (1995): 423-431.
4. Sagawa, J.Y., Watelain, E., Armand, S., Propulsion device for a manual wheelchair, Google patent: EP2862551A1
5. Saunders, Gerald A8, and Philip J. Lowe. "Wheel chair propulsion system." U.S. Patent No. 4,354,691. 19 Oct. 1982.
6. Galumbeck, Michael H. "Wheelchair." U.S. Patent No. 5,609,348.11 Mar. 1997.
7. Watwood, Brian M., et al. "Wheelchair drive assembly." U.S. Patent No. 6,755,430. 29 Jun. 2004.
8. Shaffer, Gene P. "Wheelchair." U.S. Patent No. 4,231,614. 4 Nov. 1980.
9. Pillot, Bernard. "Motorized assistance device adaptable on an elevator wheelchair and elevator wheelchair incorporating same." U.S. Patent No. 5,556,121.17 Sep. 1996.
10. Edmund, Nicholas E„ and Steven HM Kyffin. "Wheelchair." U.S. Patent No. 5,363,934. 15 Nov. 1994.
11. Coleman, Raquel. "Multi-feature automated wheelchair." U.S. Patent No. 6,154,690. 28 Nov. 2000.
12. Korosue, Akira. "Lever-operated type of wheelchair." U.S. Patent No. 4,506,900. 26 Mar. 1985.
13. Smurthwaite Jr, William J. "Manually driven wheelchair." U.S. Patent No. 7,520,519. 21 Apr.

14. Romero Sr, Bernardino S., and Bruce D. Bayes. Wheelchair hand propulsion apparatus." U.S. Patent No. 4,865,344. 12 Sep. 1989.
15. Drake, Carl F. "Manually propelled wheelchair device." U.S. Patent No. 5,941,547. 24 Aug. 1999.
c. Objective of the Invention:
i. Design and develop a TurnNTorq mechanism/retrofit/device for a wheel chair, such that, the retrofitted hand powered conventional wheel chair will have a capability to produce and transmit high torque, and also have a capability of differential driving.
ii. The mechanism delivers high torque and differential drive to ease the differently-abled person in maneuvering at irregular terrains or slopes. Moreover, the aim is to develop a wheel chair which is user friendly and economical.
d. Operational Description of the Invention:
The differential drive box of TurnNTorq retrofit mainly consist of two internal gears(A&B) and four free wheel clutches (1, 2,. 3&4) as shown irt Fig. 4.0ne set (one internal gear and two free wheel clutches) are mounted on an on one side and another set is on another side as shown in the Fig.5. (b)The total arrangement of two internal gears and four free wheel clutches on intermediate shafts is as shown in theFig.5 (a).

The operational sequence of the differential drive and high torque mechanism is explained below. From the Table 1, it should be noticed that for the wheel chair to move forward motion, the internal gears A& B should be engaged with 2& 3 respectively. So that, the both wheels will move in clock wise direction which causes the forward motion of the wheel chair. In order to move the wheel chair in backward direction, the internal gears A & B should be engaged with 1& 4 respectively.
Consequently, both wheels will move in anti-clock wise direction, which causes the backward motion of the wheel chair. For a right turn of the wheelchair, the internal gears A & B should engage with 2 & 4 respectively. So that, the wheel 1 will move in clock wise direction and the wheel 2 will move in anti-clock wise direction, which causes the right turn of the wheel chair. Similarly, to take left turn, the internal gears A & B should be engaged with 1 & 3 respectively. So that, the wheel 1 will move in anti-clock wise direction and the wheel 2 will move in clock wise,direction that causes the left turn of the wheel chair.