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If fuel, air and an electrical spark provide the means to start a vehicle’s engine, the crankshaft is the core component that turns the associated motion into driving ability.



What Is a Crankshaft?

In the world of the internal combustion engine, the crankshaft and camshaft are the king and queen of the empire. They are intrinsically linked and must operate together in complete harmony for the power produced during combustion to be transferred to the transmission system. Both components are very heavily engineered and must be able to operate within fine tolerances in a hostile environment. The crankshaft needs to endure tremendous rotational forces caused by the explosion of fuel and air in the cylinder head above.

How Does the Crankshaft Work?

A crankshaft does most of the heavy lifting and connects directly to the gearbox. It is designed in such a way that several pistons can be connected to it in a very carefully designed “step” layout. As a series of coordinated explosions happen in the combustion chamber above each piston, the said piston is forced down, turning the crankshaft as it does so, before being returned to its top position to repeat the process.

At one end of the crankshaft is a flywheel, whose job is to even out some of the dramatic forces created during operation and to ensure that the rotational force created by the pistons is ultimately transferred into linear force, that will ultimately drive the car long. The other end of the crankshaft is fitted to a pulley, which turns a serpentine belt and links to various ancillary components such as the water pump, air conditioning and alternator.

How Is a Crankshaft Made?

An increasing number of automobile manufacturers are deciding to equip their vehicles with crankshafts that are forged, rather than being cast as was previously the preferred approach. Vanadium or carbon steels are used, especially in more high-performance models as these products are better able to cope with more stringent demands and are less likely to fail under pressure. The pistons need to be linked by heavy duty connecting rods and “bottom ends” to the crankshaft and will sit on bearings and liners which are typically made from an alloy material known as “Babbitt.”

How Does a Crankshaft Fail?

  • Cracks can develop at high load-bearing positions
  • Insufficient lubrication
  • Bearing failure
  • Excessive vibration
  • General fatigue

What Are the Symptoms of Failure?

  • Excessive oil consumption
  • Engine shaking

What Are the Consequences of Failure?

  • Catastrophic engine failure

It is relatively easy to access the seal located on the front of the crankcase, but an entirely different story when it comes to the rear. It’s vital that these seals are carefully replaced as needed.

If you have questions or concerns about Crankshafts or any of your vehicle’s components, come into your local Pep Boys where we can answer any question, help you find any part, or perform any vehicle service you might need.