Centrifugal clutch and manual clutch

N.SACHIN

what is the exact difference between centrifugal clutch and manual clutch and also which one is better to use in vehicles?

There is semi-centrifugal and fully centrifugal clutch.
Semi-centrifugal clutches are used in high powered race cars, to reduce the driver effort.These are not automatic clutches , it needs a clutch pedal.There are weight levers attached to the pressure plate, as the engine gains rpm , the weight levers move outwards due to centrifugal action.This causes a force over the pressure plate, action of force is to increase pressure over the pressure plate.The end effect is that, there is no slip at all and maximum power ca be transmitted.
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Fully centrifugal clutches are automatic clutches.Working is just like semi-centrifugal clutch.The clutch action is purely under centrifugal force.At low engine rpm the centrifugal force is low, so there is slip, as engine rpm increases, so does the centrifugal force.This increases pressure on the pressure plate and reduces slip to zero.
There is a withdrawal lever in the clutch assembly, which is operated by the driver to disengage the clutch during gear shifting.Usually the withdrawal lever is provided on the gear knob itself.
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Manual clutches uses a compression spring to exert pressure on the pressure plate.
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The choice of clutch depends on the vehicle type, engine power, working environment etc.We cant say one is better than other.

there are 1,2.....5 gears for some bikes such as shine,unicorn,hero.....and there are no gears for some two wheeler vehicle such as scooty, pep.....which one is better to use either with gear or without........

N.SACHIN

there are 1,2.....5 gears for some bikes such as shine,unicorn,hero.....and there are no gears for some two wheeler vehicle such as scooty, pep.....which one is better to use either with gear or without........

Manual transmission gives better fuel economy than CVT or Continuously Variable Transmission.