In some of the most recent cars in the marketplace, you can shift gears simply by pressing a button, turning a knob or toggling a little joystick. Yet at the same time, plenty of different automobiles still require motorists to use one foot for the clutch pedal and another for the gas, all when using one hand to control the gear-change lever through a definite pattern of positions. And many other current vehicles don’t have any traditional gears at all in their transmissions.
But regardless of whether a Variable Speed Transmission vehicle includes a fancy automatic, an old-school manual or a modern-day continually variable transmitting (CVT), each unit has to do the same job: help transmit the engine’s result to the driving wheels. It’s a complicated task that we’ll try to make a little simpler today, you start with the basics about why a transmitting is needed in the first place.
Let’s actually begin with the typical internal combustion engine. As the fuel-air mixture ignites in the cylinders, the pistons start moving up and down, and that motion is utilized to spin the car’s crankshaft. When the driver presses on the gas pedal, there’s more fuel to burn in the cylinders and the complete process moves faster and faster.
What the transmission does is change the ratio between how fast the engine is spinning and how fast the driving wheels are moving. A lesser gear means optimum performance with the tires moving slower than the engine, while with a higher gear, optimum performance comes with the wheels moving faster.
With a manual transmission, gear shifting 
is handled by the driver via a gear selector. A lot of today’s cars have five or six forward gears, but you’ll discover older models with anywhere from three to six forwards gears offered.
A clutch is used to transmit torque from a car’s engine to its manual transmission. The various gears in a manual tranny allow the car to visit at different speeds. Larger gears offer lots of torque but lower speeds, while smaller sized gears deliver much less torque and allow the car travel more quickly.