In some of the most recent cars in the marketplace, you can change gears simply by pressing a button, turning a knob or toggling a little joystick. Yet simultaneously, plenty of different Variable Speed Drive Motor vehicles still require drivers to make use of 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 several other current cars don’t possess any traditional gears at all within their transmissions.
But whether or not a vehicle has a fancy automatic, an old-school manual or a modern-day continuously variable tranny (CVT), each unit must do the same job: help transmit the engine’s result to the driving wheels. It’s a complicated task that we’ll try to make a little simpler today, starting with the basics about why a transmission is needed in the first place.
Let’s actually begin with the normal internal combustion engine. As the fuel-air mix ignites in the cylinders, the pistons begin moving up and down, and that motion is utilized 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 efficiency with the wheels moving slower compared to 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 vehicles possess five or six 
forwards gears, but you’ll find older models with anywhere from three to six ahead gears offered.
A clutch can be used to transmit torque from a car’s engine to its manual transmitting. The various gears in a manual transmitting allow the car to travel at different speeds. Larger gears offer plenty of torque but lower speeds, while smaller sized gears deliver less torque and invite the car travel quicker.