In a few of the newest cars out there, you can change 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 motorists to make use of one foot for the clutch pedal and another for the gas, all when using one hand to manipulate the gear-shift lever through a definite design of positions. And many other current vehicles don’t have any traditional gears at all within their transmissions.
But regardless of whether a vehicle includes a fancy automatic, an old-school Variable Speed Drive Motor manual or a modern-day continually variable transmitting (CVT), each unit has to do the same work: help transmit the engine’s result to the generating wheels. It’s a complex task that we’ll try to make a little simpler today, starting with the basics about why a tranny is needed in the first place.
Let’s actually start with the typical internal combustion engine. As the fuel-air mixture ignites in the cylinders, the pistons begin moving up and down, and that movement is used 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 functionality with the wheels 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. A lot of today’s cars possess five or six forwards gears, but you’ll discover older models with anywhere from three to six forwards gears offered.
A clutch can be used to transmit torque from a car’s engine to its manual transmission. The many gears in a manual tranny allow the car to travel at different speeds. Bigger gears offer plenty of torque but lower speeds, while smaller gears deliver much less torque and invite the car travel more quickly.