What Is a Drive Shaft?by Chuck Ayers
A drive shaft is an elongated round shaft, usually made of steel, that runs from the engine to gears that turn the wheels of a vehicle. The pistons of an engine transfer their power to a set of gears that turn the drive shaft, creating torque. The torque is then transferred through the drive shaft to the gearing of the wheels, making them spin. It is what makes the car go.
Vertical Motion to Rotary Motion
When gas is fed into the piston chambers of the engine and ignited, it creates compression that starts the process of moving a vehicle. Pistons move up and down, and through engine and transmission gearing they rotate the drive shaft. Other gearing transmits the vertical motion into rotary motion. It makes the wheels turn.
Different Types of Drive Shafts
Although all perform essentially the same function, vehicles rely on different types of drives and need different types of drive shafts. There is typically one type of drive shaft for rear-wheel-driven vehicles, another for front-wheel-driven vehicles and another for all-wheel-driven vehicles.
There is Quadratrac, one of the latest innovations of the car industry. It's basically an all-wheel-drive vehicle that requires a drive shaft that powers all the wheels simultaneously. It also requires other parts, like differentials, to allow for differences in turning radius between the outer and innner wheels.
The exchange of force from the engine and transmission to the drive shaft creates a tension.Think about it as opening a jar of peanut butter and having to exert the same force from when you start to open the jar until you actually open the jar and get to make your peanut butter and jelly sandwich.The torque is constant on a drive shaft. What is occurring is the exchange of vertical energy to rotary energy. Except for the sandwich part.
Most cars and trucks use a straight-line or rigid drive shaft to turn the wheels. Gearing is needed to change the direction of power (or torque) from a straight-line to a rotary line of power distribution. In front-engined, rear-drive vehicles, a longer drive shaft is also required to send power the length of the vehicle. The reverse applies to rear-engine, front-wheel-driven vehicles. Either way, most drive shafts use a U-joint to allow it to flex with road imperfections (bumps and potholes) to maintain tire and vehicle stability.
Chuck Ayers began writing professionally in 1982, breathing life into obituaries, becoming a political and investigative reporter at a major East Coast metropolitan newspaper. He now freelances and is a California communications and political consultant. He graduated from American University, Washington, D.C., with degrees in political science and economics.