Driveshaft facts for kids

A driveshaft is a special rod or tube that helps move power from an engine to where it's needed, like to the wheels of a car or a machine. Think of it like a strong arm that spins to make other parts spin too.

Most engines create power by spinning something. This spinning power is called torque. A driveshaft's job is to take this spinning power from the engine and send it to other parts that need to move or do work. Driveshafts need to be very strong to handle this power, but also light enough so they don't waste energy.

A Cardan driveshaft with special joints

The driveshaft on a classic BMW motorcycle

How Driveshafts Power Cars

Most cars today use driveshafts to send power from the engine to the wheels.

Front-Wheel Drive Cars

In cars where the front wheels get the power (called front-wheel drive), there are driveshafts that connect the engine's gearbox (called a transaxle) to each front wheel. These shafts help the front wheels turn and move the car.

Rear-Wheel Drive Cars

In cars where the back wheels get the power (called rear-wheel drive), there are driveshafts that connect a special gear system (called a differential) to each rear wheel. There's also a longer driveshaft, often called a propeller shaft, that runs along the bottom of the car. This propeller shaft connects the gearbox at the front of the car to the differential at the back.

A truck's double propeller shaft

Types of Car Driveshafts

There are a few main types of driveshafts used in cars:

• One-piece driveshafts
• Two-piece driveshafts
• Slip-in Tube driveshafts

The Slip-in Tube driveshaft is a newer type. It's designed to collapse or shorten during a crash. This helps absorb energy and can protect people inside the car or truck.

Driveshafts on Motorcycles

Driveshafts have been used on motorcycles for a very long time. While many motorcycles use chains or belts to send power to the back wheel, driveshafts need less looking after and can last a long time.

One challenge with using a driveshaft on a motorcycle is that it needs special gears to turn the power 90 degrees from the shaft to the back wheel. This can cause a small amount of power to be lost.

A 1913 FN motorcycle from Belgium, which used a shaft drive

Driveshafts for Farm Tractors

Farm tractors use a special type of driveshaft called a Power Take-Off (PTO) shaft. This shaft sticks out from the back of the tractor. Farmers can connect it to different farm machines, like hay balers or corn choppers, to power them using the tractor's engine.

This is very useful because it means farm equipment doesn't need its own engine, which saves money and makes the tractor more versatile.

An old John Deere tractor with its PTO shaft under a protective cap

Driveshafts on Bicycles

Even bicycles can use driveshafts instead of chains! While they haven't become super popular, they have some interesting pros and cons.

A bicycle that uses a driveshaft instead of a chain

Why Driveshaft Bicycles Can Be Good

• Less likely to get stuck: The drive system is less likely to get jammed or broken, which can sometimes happen with chain-driven bikes.
• Cleaner ride: No greasy chain means no grease on your clothes and no "chain bite" to snag your pants.
• Less maintenance: If the driveshaft is inside a protective tube, it needs less cleaning and care than a chain system.
• Consistent performance: Some companies say driveshaft bikes always deliver power efficiently, while chain bikes can vary depending on how clean and well-maintained they are.
• More ground clearance: The driveshaft system can be higher off the ground, making it easier to ride over bumps or small obstacles.
• Harder to steal: Driveshaft bicycles look different, which can make them less appealing to thieves. They are used in some city bike rental programs in Europe.

Challenges with Driveshaft Bicycles

• Heavier: A driveshaft system usually weighs more than a chain system, often by 1 to 2 pounds.
• Less efficient at their best: When a chain is perfectly clean and well-oiled, it can sometimes be more efficient than a driveshaft.
• Limited gear options: It's harder to use many different gear ratios with a driveshaft, although special hub gears can be used.
• Wheel removal: Taking off the wheel can be a bit trickier with a driveshaft system.

Images for kids

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  3D animation of a Cardan shaft in a z-arrangement

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  A Škoda 422 car's rear axle, suspension, and driveshaft on display at the Škoda Museum

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  A truck's two-section propeller shaft

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  The exposed driveshaft on BMW's first motorcycle, the R32

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  The rear driveshaft, crankshaft, and front driveshaft of a Shay locomotive

See also

In Spanish: Eje de transmisión para niños