In a few of the latest cars out there, you can change gears simply by pressing a button, turning a knob or toggling a little joystick. Yet simultaneously, plenty of different vehicles still require motorists to use one foot for the clutch pedal and another for the gas, all while using one hand to manipulate the Variable Speed Transmission gear-change lever through a definite design of positions. And several other current cars don’t have any traditional gears at all in their transmissions.
But whether or not a vehicle has a fancy automatic, an old-school manual or a modern-day continuously variable transmitting (CVT), each unit has to do the same job: help transmit the engine’s result to the traveling wheels. It’s a complex task that we’ll try to make a bit simpler today, starting with the basics about why a transmission is needed to begin with.
Let’s actually begin with the typical internal combustion engine. As the fuel-air mix ignites in the cylinders, the pistons start moving up and down, and that movement can be 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 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 overall performance with the tires moving slower than the engine, while with a higher gear, optimum performance includes the wheels moving faster.
With a manual transmission, gear shifting is handled by the driver with a gear selector. Many of today’s vehicles have five or six ahead gears, but you’ll discover older models with from three to six forward gears offered.
A clutch is utilized to transmit torque from a car’s engine to its manual transmitting. The various gears in a manual tranny allow the car to travel at different speeds. Larger gears offer lots of torque but lower speeds, while smaller gears deliver less torque and invite the car travel more quickly.