In some of the newest cars on the market, you can shift gears simply by pressing a button, turning a knob or toggling a small joystick. Yet at the same time, plenty of different vehicles still require drivers to use one foot for the clutch pedal and Variable Speed Transmission another for the gas, all while using one hand to manipulate the gear-shift lever through a distinct pattern of positions. And many other current vehicles don’t possess any traditional gears at all in their transmissions.
But whether or not a vehicle includes a fancy automatic, an old-college manual or a modern-day continuously variable tranny (CVT), each unit has to do the same work: help transmit the engine’s result to the traveling wheels. It’s a complex task that we’ll make an effort to make a little simpler today, you start with the basics about why a tranny is needed to begin with.
Let’s actually start with the typical internal combustion engine. As the fuel-air mix ignites in the cylinders, the pistons begin moving up and down, and that movement is utilized to spin the car’s crankshaft. When the driver presses on the gas pedal, there’s more fuel to burn off 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 efficiency with the tires moving slower than the engine, while with an increased gear, optimum performance comes with the wheels moving quicker.
With a manual transmission, gear shifting is handled by the driver via a gear selector. Many of today’s cars have five or six forward gears, but you’ll find older models with 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 many gears in a manual transmitting allow the car to visit at different speeds. Larger gears offer plenty of torque but lower speeds, while smaller gears deliver much less torque and allow the car travel more quickly.