A novel gearbox for a paraplegic motorcycle.
PRIOR ART & IDEATION
In order to pursue an ambition of a paraplegic motorcycle rider for riding from Kanyakumari (Southern Tip of India) to Kashmir (Northern Tip of India), a motorcycle was retrofitted with a sidecar. This motorcycle conquered rough terrains and could handle his ride really well. It was then experienced that reversing this motorcycle is a problem as he need to depend on others for doing it. Now in order to overcome this challenge and to facilitate self sufficient solo riding, a provision of retrofitment reverse mechanism, without any alteration to the motorcycle engine and internal gearbox was needed.
Some of the prior art is cited below :
The prior art US 7156197B2 patent has prime mover which is a 12V DC Electric Motor. The available 12V DC electrical motor is not capable of moving the complete motorcycle with the sidecar assembly as the tractive effort required for propulsion is very high. The batteries used to power this motor need a very strong charging circuit which demands higher engine rpm and not possible with the Lead acid batteries. The motorcycle engine will be doing very less rpm as the rider is disabled and cannot attain high vehicle speed. Since the charging rate of the battery is always lower than the discharge rate, using this heavy duty motor might drain the battery completely. In our to be patented mechanism, the engine is the prime mover and thus all electrical problems are eliminated. Furthermore this electric motor is not constantly engaged with the final drive which means that there will be a need for engaging and disengaging of the motor from the final drive point repeatedly. This patent requires electrical inputs.
The other prior art is US 7156197B2 patented reverse mechanism with a belt drive and is thereby very costly. This arrangement does not allow the motion in dual directions in multiple gears.

The other prior art is CN 2331581Y relates to a motor tricycle, where both the rear wheels have a propeller shaft and are powered by the engine. The setup is complex and has more numbers of custom parts and moving parts. The setup is bulkier and missing of the invalid carriage does not allow the mechanism to work with a motorcycle all by its own on two wheels. The complicated tricycle setup itself is costly and the spare parts are not readily available. Also, the setup is complicated and requires skilful labour for its service and maintenance.
The other prior art is US 8001862B2 comprises of alteration to the motorcycle's existing gearbox and is subjected to engine warranty void as their parts are not OEM. This means that there is a need for internal modification of the existing components which is cumbersome. This means that every alteration is specific to particular brand or model of motorcycle and needs multiple alterations. The mechanism is complicated and requires skilfull labour for its maintenance. This patent uses helical gears which are costly and are less enernv efficient ^Efficiency of the gear^Output Shaft Power / Input Shaft Power) *100]. The efficiency of helical gear is less because helical gear trains have sliding contacts between the teeth which in turns produce an axial thrust of gear shafts and generate more heat. So, more power loss and less efficiency. This is overcome in Reverse Gearbox by using the Spur gears.
The prior art US 4523491 is a direct alteration to the existing gearbox of the motorcycle and this voids the motorcycle engine warranty. Since the number of gearing ratios obtained in forwarding direction by this patent mechanism is less due to one 3-5 gear are operational in forwarding drive, the performance of the motorcycle is poor and efficiency to absorb it full capabilities are less.

As seen above each of its have a suffering in terms of complexity, in terms of performance, in terms of lower efficiency, difficulty in assembly, power requirement, loss of warranty of engine equipments, non-flexibility, etc.
OBJECT OF THE INVENTION
The paraplegic rider owns a Classic 500 desert storm which served as a platform for the concept generation. The motorcycle was self balanced by a side-car assembly (retro-fitted for a different vendor) and served him as a channel to travel round the country. As rider is a specially abled who is unable to use all the foot controls, a hand shift with combi- brakes were installed to ensure smooth propulsion on his rides. The modifications made on the motorcycle were constrained with use of standard parts to facilitate ease of servicing the motorcycling, availability of spares, cost reduction for modification.
The current designs which are readily available in the market involve having alterations done either inside the motorcycle engine or and additional provisions made to the engine itself. The main objectives and of making a reverse gearbox are as follows:
One of the object is there are lots of RE motorcycles users out in the world who already own one with them. Now to encourage and pursue a passion for specially-abled riders the concept of providing a kit would make more sense as they can access this kind a kit without any additional fabrication required to their motorcycle.
The other object is the kit ensures that there is no internal alteration with the engine of the motorcycle and thus it does not alter the warranty life of the engine. The motorcycle engine payloads differ after this kit is fixed to the motorcycle to the company claimed payload.

The other object is the kit can be used with a versatile usage on an invalid carriage to the motorcycle, be it a sidecar or and additional wheels or any other supporting wheelers.
The other object is the kit fixes on the motorcycle and is independent of the invalid carriages thus in near future can be tuned to reverse the motorcycle by itself.
The other object is the motorcycle has a Unit Construction Engine (UCE) which is completely different from the Lean Burn Engine (LB). There are modifications available in the LB where the engine is altered in order to provide a reverse action. In the proposed kit the Reverse gearbox can be coupled with any type of the engines in order to deliver reverse action.
The other object is the concept of transfer shaft is unique in the Reverse Gearbox and has a valid function for its presence.
The other object of the invention is to ensure that there is no demand of power requirement for this retrofit.
The other object of the invention is to use the engine as prime mover thereby eliminating power requirement and associated electrical problems.
The other object is to ensure that the new mechanism shall be continuously connected with the final drive.
The other object is to ensure that the new mechanism is meshed with the final
drive.
The other object of the invention is to create components wherein the components have better iongetivity in comparison with existing components.
The other object of the invention is to ensure that the invention is operable with the engine power solely with no demand for additional power from other sources.

The other object of the invention is to have the invention with the reverse gear box having a chain drive which is more advantageous than the belt drive.
The other object of the invention is to have the invention of reverse mechanism which is cost effective.
The other object of the invention is to design a reverse gear which enables the rider to reverse the complete motorcycle drive forward and reverse under various gearing ratios in the motorcycle transmission. That means the motorcycle can attain 1-5 gears in forward as wells as in reverse direction.
The other object of the invention wherein the reverse gear is designed such that only one wheel powered by the engine and is sufficient to propel the motorcycle in desired forward and reverse directions.
The other object of the invention is to have the reverse gear mechanism setup which is not complex, there is no requirement of custom parts and moving parts.
The other object of the invention is to have the reverse gear mechanism setup which is light in weight and avoids bulky items.
The other object of the invention is to have the reverse gear mechanism which is coupled directly with the engine - rear wheel, which makes its usage under various applications without any alteration to the reversing mechanism of the existing vehicle.
The other object of the invention is to have the reverse gear mechanism which can be retrofit to the existing vehicle and there is no need for skillful labour for assembly, fitment, its service and maintenance.
The other object of the invention is to have the reverse gear mechanism which is completely independent of the engine and thereby not offending the engine warranty and does not disturb the parts.
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The other object of the invention is to have the reverse gear mechanism which is independent of the motorcycle engine and is just coupled using a chain. Thus no internal modifications are done to the existing motorcycle engine where the reverse gearbox fits.
The other object of the invention is to have the reverse gear mechanism which is independent of the model of the motorcycle. It is flexible to be mounted universally on any conventional motorcycle.
The other object of the invention is to have the reverse gear mechanism is to avoid using gears which are complicated and expensive which is the practice in prior art. Many prior art use helical gears which are costly and are less energy efficient [Efficiency of the gear=(Output Shaft Power / Input Shaft Power) *100]. The efficiency of helical gear is less because helical gear trains have sliding contacts between the teeth which in turns produce an axial thrust of gear shafts and generate more heat. So, more power loss and less efficiency. The object is to overcome in this Reverse Gearbox by using the Spur gears.
SUMMARY OF INVENTION
In order to provide a mechanism to work individually from the existing powertrain was a big challenge as this would alter the service intervals, mechanical life of the engine, avoiding the warranty and multiple component failures. Thus the only option was to introduce a unit between the engine sprocket and the rear wheel sprocket which can allow the bike to propagate forward and reverse with a simple lever. This can be done by a reverse gearbox. Thus using Royal Enfield's existing motorcycle gearbox, create a new gearbox which can conveniently reverse the final drive and put it back to a forward drive. The below diagram gives a brief idea how this can work. In the stock existing setup the engine is coupled with the final drive and rear wheel by the means of chain. Now in the modified setup the engine will coupled to a reverse box and the reverse box will be coupled with the help of
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chain or belt to the final drive and rear wheel. The reverse function can be adjusted with the movement of reverse lever on the reverse box. Also the forward function can be obtained the placing on the reverse lever back to its original position.
FIGURE 1 - LHS
E - Engine
C » Chain
W - Final drive and rear wheel
FIGURE 1 - RHS
E - Engine
C/B - Chain / Belt
R - Reverse Gear Box
W - Final drive and rear wheel
PARTNUMBERS MARKED IN DRAWINGS

PART NUMBER PART NAME
1 Aluminum Casing
2 Reverse Gearbox Mounts
3 Input Sprocket
4 Output Sprocket
5 Oil Filer Cap
6 Input Sprocket Shaft Gears
7 Transfer Shaft
8 Transfer Gears
9 Dog Clutch
10 Output Sprocket Shaft
11 Output Sprocket Shaft Gearsa
12 Input Sprocket Shaft
13 Idler Gear
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DESCRIPTION OF THE REVERSE GEARBOX
Illustration is given in Fig.1, 2 & 3
CONSTRUCTION
The reverse gearbox (RG) consist an aluminum casing where the gear assemblies are mounted on the three shafts. There is a oil filler port covered with the filler cap which allow the user to pour oil in the reverse gearbox. There is a drain plug at the bottom of the case in order to drain used oil from the reverse gearbox drain port. The exterior of the gearbox consist of two sprockets; 1. Input sprocket 2. Output sprocket.
The pictures of a working prototype is as follows:
1. The input sprocket (l/P) is mounted on the input shaft which is also called as the primary shaft. There are two gears on the shaft which are constantly in mesh with the gears on the main shaft.
2. The output sprocket (O/P) is mounted on the output shaft caiied as main shaft, where there is a dog clutch placed. The sliding movement of the dog clutch will enable reverse and forward motion of the output sprocket.
3. The third shaft is the layshaft where an idler gear is fixed, which enables reverse motion of the output sprocket.
4. There is a rocker shaft which is connected to a cable at one end and a selector fork at the other end which slides the dog clutch on the O/P shaft.
5. The next shaft is the transfer shaft which holds transfer gears. The importance of this shaft is to increase the distance between the two sprockets.
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All the shafts are supported with bearings on both the sides, and these bearings are enclosed within the casing. The RG is a constant mesh type gearbox and there is a spring to ensure that the dog clutch is always engaged to the output sprocket gear internally in order to provide forward motion of the motorcycle in default condition. The reverse motion can be achieved by shifting the dog clutch. The O/P sprocket is connected to the rear wheel final sprocket of motorcycle.
WORKING OF THE REVERSE GEAR BOX OF THE INVENTION
FORWARD DRIVE OR DEFAULT DRIVE
The engine is the prime source of energy and engine sprocket is the prime mover of the complete gearbox and rear wheel assembly. Once the engine is powdered, it drives the engine sprocket which is linked via chain to the input sprocket of the of the RG. Due to the constant mesh nature of the RG, internally the gears on the O/P sprocket shaft and l/P sprocket shaft are always engaged with each other with the help of transfer gears. The dog clutch plays a prime role here as it reverses and forwards the O/P sprocket as per rider requirements. In order to establish a forward motion of the rear wheel final sprocket, the primary engine sprocket drives the l/P sprocket which internally drives transfer gears; driving the output sprocket with the help of the gears and dog clutch engaged in forward position. The spring allows the dog clutch to be constantly engaged with the forward gear on the O/P sprocket shaft during the default condition. Thus during steady state default condition of the RG the drive derived is the forward drive.
REVERSE DRIVE
During the reverse motion, the cable attached the selector fork is pulled and it drives the dog clutch to engage the reverse gear on the O/P sprocket shaft. The drive train has its prime mover as the engine sprocket coupled to the l/P sprocket which drives the transfer gears. The engine sprocket drives the l/P sprocket and l/P sprocket shaft drives the internal gears. Now the change is
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the l/P shaft gear is not directly coupled with the O/P shaft gear but coupled with a idler gear and the idler in turn coupled with the O/P shaft gear. This allows O/P gear to rotate in opposite direction to direction of the l/P gear. Thus there is a reverse motion obtained at the O/P sprocket which reverses the final sprocket of the rear wheel.
The description is given with respect to illustrations and embodiments. The invention is however covering all the variations and modifications that will be known to skilled person in the art.

WE CLAIM
A reverse gear box for a motorcycle with its engine coupled with final drive and rear wheel by means of chain, characterized in disposing a reverse gear box therein between the engine on its one side and final drive and rear wheel on its other side, the said reverse gear box, comprising :
a. an input and output sprockets disposed external to reverse gear box, the
said output sprocket adapted to a rear wheel final sprocket of motorcycle,
b. an input / primary shaft mounting the said input sprocket and having two
gears,
c. an output / main shaft mounting the said output sprocket and having two
gears in constant mesh with corresponding two gears of input shaft,
d. a layshaft mounting an Idler gear mounted therein between the input shaft
gear and the output shaft gear,
e. a transfer shaft mounting a transfer gear, for engaging internally the gears
on output sprocket shaft with gears on input sprocket shaft,
f. a slidable dog clutch mounted on output shaft,
g. a spring engaging the dog clutch to a forward gear of the output sprocket
yccu Oi uuipui 01 ion,
h. a selector fork engaging the dog clutch to a reverse gear of the output
sprocket gear of output shaft, and i. a rocker shaft with a cable connected at one end and the selector fork
connected at its other end, operating the sliding motion of the dog clutch
mounted on output shaft, the said arrangement allowing the motion of motorcycle forward and reverse with a lever.
A motorcycle having a reverse gear box as claimed in claim 1.