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DISCUSSION Spur gear & Helical gears: Cutaway model Spur gear: This gear system I the easiest and visualize gear system to transmit power to parallel shafts. Also this is the common gear system which used in many mechanical devices. This gear system commonly used in high torque low speed drivers.

Advantages     

Transmission efficiency is high than other gear system. Straightforward design. It has constant velocity ratio. Reliability Easy to assemble.

Disadvantages  Limited center distance  Noise is high  Spur gears take significant stress.

Applications  Used in vehicle engines.  Used in aircraft engine  Used in railway trains.

Helical gears Helical Is most common used gear system in transmission. They also generate large amount of thrust and use bearing to help support the thrust and use bearing to help support the thrust load. Helical gears can be used to adjust the rotating angle by 90deg. When mounted perpendicular shafts.

Advantages  Silent operation.  Non parallel shaft can handle.  Strength is higher than the spur gear.

Disadvantages    

There Is a greater degree of friction between the teeth. The helical gear efficiency is lower than the other gear systems. Higher manufacturing cost than the spur gear. Thrust which results along the gear axis.

Application     

Vehicle gear box. Machine tools. Used in fertilizer industries and printing industries. Used in steel rolling mills. used in textile industries ,plastic industries, elevators, blowers and compressor etc.

Worm gear model This gear system consists of two elements those are worm screw and worm wheel. A worm drive can reduce rotational speed or transmit higher torque. This gear system can transfer motion in 90 degrees. Also this gear system can rotate only one direction gear will lock for other direction motions.

Advantages  Higher speed reduction  Worm and worm gear operate silently  It has self locking it will restrict the reverse movement.

Disadvantages    

Manufacturing cost Is high Cost of raw material to manufacture the worm gear is high. Efficiency is low. It has heavy power losses.

How cans worm gear is reversible To get reversible rotating motion it Is necessary to connect ac motor to the worm of the worm and worm gear system.

Planetary gear model The planetary gear system consists of mainly three components:  The sun gear  The planet gear and the planet gear’s carrier  The ring gear Each of these three components can be the input, the output or can be held stationery. Choosing which piece plays which role determines the gear ratio for the greatest.

Advantages      

This gear system is used to get higher gear ratio in compact space. Planetary gear has light weight as compared to traditional gear systems. Power transmission efficiency will be quiet good. It has higher torque transmission capability and will have a lower inertia. Driven and driver equipment can arrange in same gear system. It has higher stability.

Disadvantages      

Cost of planetary gear system is higher than the normal gear system. Designing and manufacturing is very complex. Determination of efficiency Is very difficult. Gearing should be accurate. Some of these gearing system make noise. To avoid any additional gearing, driver and driven members must be concentric.

Application    

Used in clocks. Lunar calendar Car mirrors toys

Continues variable transmission (CVT) model

A continuous variable transmission, or CVT, is a type of automatic transmission that provides more useable power, better fuel economy and a smoother driving experience than a traditional automatic transmission.

Advantages  Compact design.  Stepless acceleration.  Fuel efficiency.

Disadvantages  Cost and maintains is hard  Different driving experience.

Applications      

A high power/density belt. A set of Cone pulleys. Hydraulic Actuator. Mechanical torque sensor. Microprocessor. Torque Converter or Multi-layered clutch (replacing conventional clutches).