A car engine relies on a series of moving parts that work together to generate power, and the crankshaft is one such important part. This mechanical component helps transform the pistons’ up-and-down movement into a circular motion, ensuring the vehicle moves smoothly. Understanding how the engine crankshaft works simplifies maintenance and also helps prevent expensive repairs.
This blog discusses what is a crankshaft, its types, working mechanism and the key components that make it function effectively.
What is a crankshaft?
A crankshaft is a key engine component that converts the up-and-down motion of the pistons into rotational motion. This rotation powers the wheels and allows the vehicle to move. The car crankshaft sits at the bottom of the engine block and connects to several parts, including pistons and bearings.
Types of Crankshaft
Let’s look at the main types of crankshafts used across different engines. Each type differs in strength, manufacturing method and application:
● Fully built
This type is made by joining separate parts such as crankpins, main journals and webs through shrink fitting. They are mostly seen in older engines and are less common today because of their durability concerns.
● Welded
This shaft type is created by welding individual components using methods like friction welding. They offer better joint strength and precision than fully built designs.
● Forged
They are formed by compressing heated metal billets using forging dies. They are known to be highly durable and ideal for high-performance or commercial vehicles.
● Cast
This shaft type is produced by pouring molten iron into moulds. They are cost-effective and commonly used in passenger cars, though less suited for heavy stress.
● Billet
They are machined from a single block of high-grade alloy steel. The billet is known to be extremely strong and typically used in motorsports or heavy-duty applications.
● Solid single-piece
Solid single-piece pistons are manufactured from a single piece of material, typically through forging or casting. They offer high reliability and good fatigue strength, making them suitable for both low-speed and high-speed engines where durability and consistent performance are important.
Components in the crankshaft of a car
Below are the key components that make up a car crankshaft, each playing an important role in engine movement:
- Main journals: These are the primary supports of the crankshaft that allow it to rotate smoothly within the engine block.
- Crankpins: Also called connecting rod journals, they connect the pistons to the crankshaft.
- Crank webs: These are flat, vertical plates that join the main journals and crankpins and help transfer motion.
- Counterweights: They are used to balance the crankshaft, reducing vibration and stress on it.
- Thrust washers: They help control the crankshaft’s axial movement and also maintain the correct position within the engine block.
- Oil passages: These are small channels that allow lubrication to flow across the crankshaft components.
- Crankshaft bearing: They support rotation and reduce friction between the crankshaft and engine block.
Understanding the crankshaft mechanism
The base mechanism of the crankshaft is to convert the pistons’ up-and-down motion into rotation, which helps power the wheels and keeps the engine running smoothly. When the piston moves down after combustion, the engine crankshaft turns due to the force applied on the crankpin. As the crankshaft rotates, it pushes the next piston upward, creating a continuous cycle.
Materials used for making a crankshaft
Crankshafts are manufactured using strong and durable materials to ensure their handling of high pressure and continuous rotation. Common materials include forged steel, known to offer excellent strength for high-performance engines, and cast iron, a cost-effective and widely used material in passenger vehicles. Alloy steel is another preferred choice because it provides a balance of strength, wear resistance and durability. Some high-end or racing engines use billet steel, which is machined from a solid block for maximum reliability.
Advantages of the crankshaft
A crankshaft offers these important benefits that support smooth and reliable engine performance:
- Smooth power conversion: It converts the pistons’ up-and-down movement into rotation, helping the car move smoothly and efficiently.
- Engine balance: Counterweights help minimise vibrations and stress during engine operation, improving driving comfort and reducing wear on engine parts.
- Consistent performance: It keeps piston cycles well-timed for steady power delivery, supporting better acceleration and overall engine response.
- High load strength: The crankshaft can withstand heavy pressure and continuous rotation, making it durable for both small and high-performance engines.
- Improved efficiency: A well-designed crankshaft supports better fuel use and also helps maintain stable engine performance over time.
Conclusion
The crankshaft is one of the most crucial components in a car engine. It is responsible for ensuring the smooth conversion of piston movement into rotational power. Its design, material and working mechanism directly influence the engine performance, durability and driving comfort.
At the same time, having car insurance can provide financial support against damages, accidents and theft.
FAQs
1. Where is the crankshaft located?
The car crankshaft is located at the bottom of the engine block. It connects to pistons, bearings and other moving parts.
2. What is a crankshaft position sensor?
It detects the crankshaft’s exact position and speed. This information helps control ignition timing and fuel injection.
3. What causes crankshaft damage?
Damage can occur due to poor lubrication, worn bearings or overheating. Sudden impacts or engine failure can also affect the crankshaft.
4. Can a crankshaft be repaired?
Minor surface issues may be repaired by machining. Severe cracks or breaks usually require full replacement.
Disclaimer: The information provided in this blog is for educational and informational purposes only. It may contain outdated data and information regarding the topic featured in the article. It is advised to verify the currency and relevance of the data and information before taking any major steps. ICICI Lombard is not liable for any inaccuracies or consequences resulting from the use of this outdated information.
Related Articles:
What is a DOHC engine?
SOHC vs DOHC: Key differences explained
Drive Shaft in Cars
Propeller Shaft: Functions and Types
Guide to Basics of Engine Repair