CHAINLESS CYCLE USING GEAR DRIVE MECHANISM

Ch.Venkata Rajesh 1 , D. Suneetha 2 and K. Abraham 3 . 1. Assistant Professor (Author 1&2), Audisankara College of Engineering & Technology (Autonomous), Nh-5, Bypass Road, Gudur, Spsr Nellore, Andhra Pradesh-524002. 2. Associate Professor Audisankara College of Engineering & Technology (Autonomous), Nh-5, Bypass Road, Gudur, Spsr Nellore, Andhra Pradesh-524002. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History

The invention relates to bicycles drive mechanism, and in particular to a chainless drive mechanism for transmitting the pedal actuated driving force to the rear wheel. Another type of multispeed drive mechanism for bicycles is known as the chainless type. This mechanism uses a shaft of a chain for transmitting the pedal actuated driving force to the rear wheel. A chain less drive mechanism for a bicycle using a rotatable drive shaft for transferring the pedal actuated driving force from the pedal crank shaft to the rear wheel including shaft mechanism to provide different drive ratios. Many of these mechanisms use expensive bevel or angled gears which intermesh with rings gear mounted on the rear wheel axle or pedal crank shaft.
The intermeshing gears on the rear wheel slip automatically upon stopping or slowing down of the rotation of the pedal crankshaft and drive shaft, permitting continued rotation of the rear wheel gear during costing of bicycle.
Working:-Multispeed bicycles have become ever increasingly popular in the past several years and are accounting for a large portion of bicycle sales. The speed advantages and ease of operation of these multispeed bicycles are some of the main factors increasing their popularity. The most common multispeed transmission for these bicycles is the derailleur gear chain drive system. The derailleur chain drive system comprises a plurality of sprockets of various sizes mounted on the rear wheel shaft in combination with a shifting mechanism which causes the chain to move ISSN: 2320-5407 Int. J. Adv. Res. 5 (6), 194-199 195 from one sprocket to another, together with a spring actuated device to adjust and maintain the correct tension in the chain. The various sizes of the drive sprockets provide for the selection of a desired gear ratio depending upon the particular terrain over which the bicycle is being driven.
Such derailleur systems, however, are relatively expensive, complex and are subject to substantial maintenance problems due to the use of a chain and the continual movement of the chain between sprockets to achieve the desired gear ratio.
Another type of multispeed drive mechanism for bicycles is known as the "chainless" type. This mechanism uses a shaft instead of a chain for transmitting the pedal actuated driving force to the rear wheel. Various types and arrangements of chainless bicycle drive mechanisms have been developed in the past which use such drive shafts for transmitting the driving force supplied by an operator through the pedal actuated crankshaft to the rear wheel. Many of these mechanisms use expensive bevel or angled gears which intermesh with ring gears mounted on the rear wheel axle or pedal crankshaft. Examples of such prior mechanisms are shown in U.S. Pats. Nos. 479,470, 506,685, 589,266, 614,969, 624,964, 649,878, 1,334,108 and 2,378,634.These mechanisms also are provided with means for shifting the intermeshing gears selectively into engagement with a selected ring gear to affect the gear change or speed ratio adjustment. Another known type of chainless multispeed bicycle drive mechanism is shown in U.S. Pat. No. 3,863,503, which uses an axially adjustable two piece drive shaft having gears on the ends thereof, which gears selectively engage concentric gear teeth formed on a pair of front and rear discs.
Various problems exist with such known constructions in that the concentric gear rings or teeth on the discs are expensive to produce since they require elaborate machining and manufacturing procedures. Likewise, the intermeshing gears are of the expensive bevel gears. 196 Spiral bevel gear Alignment:-Have curved teeth at an angle allowing tooth contact to be gradual and smooth. Spiral bevel gears In our cycle we are used four spiral bevel gears with different teeth.  Differing of the number of teeth (effectively diameter) on each wheel allows mechanical advantage to be changed. By increasing or decreasing the ratio of teeth between the drive and driven wheels one may change the ratio of rotations between the two, meaning that the rotational drive and torque of the second wheel can be changed in relation to the first, with speed increasing and torque decreasing, or speed decreasing and torque increasing.

2.5:-
197 Disadvantages:- One wheel of such gear is designed to work with its complementary wheel and no other.  Must be precisely mounted.  The shafts' bearings must be capable of supporting significant forces

Universal joint:-
Universal joints are available in steel or in thermoplastic body members. Universal joints made of steel have maximum load-carrying capacity for a given size. Universal joints with thermoplastic body members are used in light industrial applications in which their self-lubricating feature, light weight, negligible backlash, corrosion resistance and capability forhigh-speed.
Universal joints of special construction, such as ball-jointed universals are also available. These are used for highspeed operation and for carrying large torques. They are available both in miniature and standard sizes.
Advantages:-Low side thrust on bearings, large angular displacements are possible, high torsional stiffness, High torque capacity.
Disadvantages:-Velocity and acceleration fluctuation increases with operating angle, Lubrication is required to reduce wear, Shafts must lie in precisely the same plane, Backlash difficult to control.

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Theoritical proof:-Here we can prove the shaft drive cycles will transmit more power than the chain drive cycles by this method. By given same load at both cycles. In shafts drives if u give the 1000 N load at pedal shaft, 7 KN power will be transmitted from larger sprocket to pinion sprocket.