Everything Cars

What is a crankshaft?

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Ever wondered what the crankshaft, a term you probably read somewhere or heard your mechanic talk about, actually is? You’re in the right place to find out. Read on.

Your engine’s crankshaft runs inside the bottom end of the car’s motor and converts the vertical movement of the pistons into horizontal rotational movement, which ultimately drives the wheels via the gearbox.

In modern cars, the crankshaft consists of some evenly spaced ‘throws’ (these are usually equal to the number of pistons in your engine – that means a four-cylinder engine will have a crankshaft with four throws), which are attached to the bottom of the pistons by connecting rods. These ‘throws’ are offset from the axis of the crankshaft, and that creates the rotational energy.

A great animation of the crankshaft working (red) from Wikipedia.org (black = flywheel, gray = pistons, blue = cylinders)

The crankshaft is attached to the engine by large bearings at either end. It connects to the flywheel, and through that, the clutch. When the clutch is engaged, the rotational energy generated by the crankshaft is transmitted through the gearbox and on through the differential to the driveshafts, which are attached to the wheels – and that’s creating the car’s ability to move.

I know, I know, it’s not the easiest explanation but then again, the crankshaft is a complex piece of engineering. The crankshaft doesn’t only consist of the crank throws. Key parts of what makes the crankshaft include crank pins, oil passages, the keyway, main journals and the flywheel mounting flange.

The engine crank also has in-built weights and balances that have the role to reduce the virbrations to a minimum as the crankshaft rotates. These vibrations could be magnified amd would cause serious damage. But that’s why we have a crankshaft position sensor – to detect any faults.

There you have it! A short but understandable easy explanation of what is a crankshaft.

I hope you found this small article useful!

You might also like to find out what the crankcase is.

Car enthusiast. I am dedicated to maintaining my cars as best as I can. I love things that work, and I love keeping them in a good state.

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