In a few of the most recent cars on the market, you can shift 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 gear-change lever through a definite pattern of positions. And many other current cars don’t possess any traditional gears at all within their transmissions.
But regardless of whether a vehicle has a fancy automatic, an old-college manual or a modern-day constantly variable transmitting (CVT), each unit must do the same work: help transmit the engine’s result to the driving wheels. It’s a complicated task that we’ll try to make a bit simpler today, you start with the basics about why a tranny is needed to begin with.
Let’s actually begin with the normal internal combustion engine. As the fuel-air mixture ignites in the cylinders, the pistons start 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 off in the cylinders and the whole 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 lower gear means optimum overall performance with the wheels moving slower than the engine, while with a higher 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 possess five or six ahead gears, but you’ll discover older models 
with anywhere from three to six forwards gears Variable Speed Drive Motor offered.
A clutch is used to transmit torque from a car’s engine to its manual transmission. The many gears in a manual tranny allow the car to visit at different speeds. Bigger gears offer plenty of torque but lower speeds, while smaller sized gears deliver less torque and invite the car travel quicker.