Monday, April 25, 2011

Manual Transmission


Changing gears may be tiring in traffic but it is necessary to keep the car’s engine at the right speed compared to the road speed of the vehicle.

Ever wondered why it is that the driver has to depress the clutch pedal and change gears while driving a car? It is necessary for regulating torque transfer from the internal combustion engine. Cars need a transmission due to the physics of the internal combustion engine.

All engines have a maximum RPM value or a redline beyond which the engine cannot perform revolutions. Every engine has a RPM band in every gear which generates maximum horsepower and torque. The driver shifts gear to stay below the redline and near the RPM band of its best performance.

The Clutch engages and disengages the drive shaft from the gear box allowing the driver to select the appropriate gear judging by the road speed at which the car is to be driven at. In a typical 5 speed gear box the clutch disengages and engages different gears to the output shaft which is connected to the differential which drives the wheels of the car. When the car is to be moved from stationary position the gearbox is moved from 1st to 5th as the car picks up speed.

There is always more torque at lower gears as compared to higher gears. Always use lower gears while driving up a hill surface. Also, use lower gears while driving down a hill when the road surface is slippery or loose, this ensures that the car does not exceed a certain speed which the gear cannot go to thereby keeping the speed of the vehicle slow. Second gear is the ideal gear for such situations. Higher gears have less torque compared to lower gears but allow higher road speeds.

Selecting a higher gear and driving at low RPM increases the fuel efficiency of a car, but if the speed is too low for the gear the driver can hear a clattering noise which means a lower gear needs to be engaged as the speed is too low for the current gear to carry and can damage the mechanical components of the car.

Although modern cars come with rev limiters which do not allow the driver to exceed a certain RPM or engine speed, it is not recommended to touch maximum RPM too frequently as it can damage the engine.
Cars have only one reverse gear because there is no need to drive fast while going backwards, it is only used to manoeuvre the car. That is what would happen if a car had only one forward gear.

No comments:

Post a Comment