In a few of the latest cars on the market, 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 drivers to use one foot for the clutch pedal and another for the gas, all when using one hand to control the gear-shift lever through a definite design of positions. And many other current vehicles don’t possess any traditional gears at all within their transmissions.
But regardless of whether a vehicle has a fancy automatic, 
an old-school manual or a modern-day continuously variable transmission (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 make an effort to make a bit simpler today, starting with the fundamentals about why a transmission is needed to begin with.
Let’s actually begin with the normal internal combustion engine. As the fuel-air mix ignites in the cylinders, the pistons begin upgrading and down, and that motion is used 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 whole process moves quicker 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 lower gear means optimum functionality with the tires moving slower compared to the engine, while with a higher gear, optimum performance includes the wheels moving quicker.
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 find older models with Variable Speed Transmission anywhere from three to six forwards gears offered.
A clutch is utilized to transmit torque from a car’s engine to its manual transmission. The various gears in a manual tranny allow the car to travel at different speeds. Bigger gears offer lots of torque but lower speeds, while smaller gears deliver less torque and allow the car travel quicker.