Crankshaft

What Is Crankshaft?

The crankshaft is a rotating shaft containing one or more crankpins,a crucial element in the transmission system, the crankshaft plays a pivotal role by converting the reciprocating motion of the piston into a continuous rotational motion, facilitating the generation of useful power from the piston's back-and-forth movement. Any errors in its design can significantly elevate the risk of engine failure. The crankshaft's significance is underscored by its connection to both the engine and the flywheel, forming an integral link in the machinery's power transmission system.

Advantages of Crankshaft

Improved efficiency

Smooth engine operation

Better torque for improved performance

Increased engine power

Why Choose Us

Our Factory
Liubei engine factory, located in jinhua, zhejiang, is a leading global provider of automotive power solutions. Since its establishment, we have been committed to designing, manufacturing, and providing innovative, reliable, and efficient engine products, contributing to the development of the automotive industry

One-stop Solution
Strive to build the best one-stop auto parts service platform in china, make auto parts services easier, go further, achieve customers,and achieve ourselves

Advanced Equipment
Our factory is equipped with the most advanced production equipment and automated production lines:
High precision cnc machine tools and machining centers
Intelligent assembly line and robot system
Advanced detection and testing equipment
Environmentally friendly manufacturing process
The application of these devices and technologies ensures that our products reach industry-leading levels in terms of quality, performance, and reliability

Quality Control
We have implemented a comprehensive quality management system, from raw material inspection to final product testing, and every process undergoes strict quality control. Our engine products comply with international standards and have passed multiple rigorous certifications and tests.

Customized Services
We provide personalized accessory recommendations and customization services to ensure that the accessories you choose perfectly match your vehicle model and usage needs

Types of Crankshaft

Fully Built Shaft
A 'fully built shaft' crankshaft has crankpins, main journals, and webs as main components. These parts are usually made using steel casting or forging and are joined together using shrink fitting. This type of crankshaft was common in older engine models but has seen reduced usage due to issues with grain flow and weakness at the joints.

Welded Shaft
This kind of shaft is created by joining multiple parts through welding techniques such as friction welding. In this, parts are pressed together with high-speed rotation to create friction that heats the parts to a plastic-like state and allows them to be forged together.

Forged Crankshaft
They are made by compressing heated steel billets into shape with forging dies. This process creates a uniform grain structure, producing a more robust and durable crankshaft.

Solid Single Piece Crankshaft
They are formed from a single piece of material through forging or casting. Their design can endure the load during firing and cyclic tension, making them suitable for both high-speed and low-speed engines.

Billet crankshaft

Billets are machined from a single solid piece of premium alloy steel. They offer unmatched toughness and are custom-made to match specific project requirements. They are known for their low drag coefficient and are often used in high-performance applications.

Cast crankshaft

Cast crankshafts are produced by pouring molten material, typically cast iron, into a mould to create a raw casting. Due to their less precise grain structure, cast crankshafts may not be suitable for high-performance applications.

Semi-built shaft

This crankshaft is not fully assembled from many parts; crank webs are fully forged and then shrink-fitted to the bearing journal. This process results in a continuous grain structure over the crank web to offer better fatigue strength. You can find them in large marine engines. They are also preferable in modern engines due to their construction advantages.

曲轴 OEM 13401-54020、13401-54060、13401-54080、13401-54100 适用于丰田 Vigo Hilux、HiAce Land Cruiser、Prado J90、Dyna 150 发动机：3L-E/5L-E

Application of Crankshaft

Automobile engines

Industrial machinery

Marine engines

Power generators

Aircraft engines

Reciprocating pumps and compressors

Components of Crankshaft

Flywheel Flange:
As the name suggests the flywheel of the vehicle is attached to the crankshaft with the help of a flywheel flange. Flywheel flange is attached to one end of the crankshaft.
It is designed in such a way that it can hold the flywheel rigidly. This is because the flywheel is a heavy mechanical device that rotates at very high rpm.

Pulley End:
The pulley end of the crankshaft is connected to the engine and it can also be connected to the gearbox.

Counterweight:
The counterweight is the most important element of a crankshaft. These help in the smooth running of the crankshaft. When the piston reaches the top dead center the heavier side of the counterweight reaches its lowest point.
And when the piston reaches the bottom dead center the heavier side reaches its highest point. This results in smooth running due to the change of potential energy created by the counterweights.

Balance Weight:
The balance weights are some additional weights that are located in the counterweights to provide improved stability.

Main Bearing Journals:
The main bearing journal has its axis coinciding with the axis of the pulley end and the flywheel flange. These act as the connecting elements between the counterweights. The main bearing journal also forms the axis of rotation for the crankshaft.

Rod Bearing Journals:
The rod-bearing journals are used to connect the piston with the crankshaft. The pistons are attached to the rod-bearing journals with the help of pins.

Oil Passage:
Oil passage is the passage that connects the main journal bearing to the rod journal bearing. The oil from the main journal bearing flows towards the rod journal bearing for lubrication purposes.

Material of Crankshaft

Manganese-molybdenum Steel:

Forged crankshafts, suitable for moderate-duty petrol engines.
Composition: 1.5% manganese, 0.3% molybdenum, 0.38% carbon, and 97.82% iron.
Brinell hardness number: Approximately 250 BHN.

Chromium-molybdenum Steel:

Used in medium and heavy-duty petrol and diesel engines.
Composition: 1.2% chromium, 0.4% molybdenum, 0.3% carbon, with the rest being iron.
Brinell hardness number: Around 280 BHN.

Nickel-chromium-molybdenum Steel:

Ideal for diesel engines with very high fatigue strength.
Composition: 2.5% nickel, 0.31% carbon, 0.65% chromium, 0.5% molybdenum, and the remaining iron.
Brinell hardness number: 300 BHN.

Nodular Cast Iron:

A type of grey cast iron with graphite nodules in a perlite medium, known for high ductility.
Composition: Carbon content around 3-4% and silicon content around 1.8-2.8%.
Brinell hardness number: Approximately 200-300 BHN.

How to Maintain Crankshaft

Proper installation

Prevention for any pre-existing damage that may arise in your crankshaft will depend on the installation process. You can amend any damage even before installation on your connecting rods and main bearing center.
When inserting the bearing caps and bearing shells, always ensure that you maintain the oil bores' cleanliness and the diameters of connecting rod journals and main bearing. Make sure that you appropriately clean the oil ducts in your engine's crankcase with compressed air. Use recommended oils on the sliding surfaces of your bearing shells.

Lubrication

Proper lubrication is needed for the crankshaft to provide turbulent motion. The pressure lubrication comes from the oil pump supplying the lubricant to the pre-drilled passages and holes in the crankshaft journals and axis. The oil level provides splash lubrication in the crankcase and the turbulent motion of the crankshaft.
The oils usually used for lubrication of crankshaft are oxidation restricted circulating oils and rust or engine oils, which incorporate viscosity indicator improvers, oxidation inhibitors, and anti-wear additives to extend the lifespan of the crankshaft.

Don't overfill with oil

Overfilling your crankcase with oil will cause the rise of oil into the crankshaft, which in turn will cause cavitation of the oil. Your engine's oil pump will not circulate properly if your oil has both oil air bubbles. It can cause too much force on the engine components and may cause overheating as well.

Process of Crankshaft

The construction of crankshafts often relies on cast iron because of its excellent durability and ability to withstand the demand of engine operation. In certain cases, crankshafts are also manufactured using forged steel to withstand the heavy load involved.

Cast iron crankshafts are created through a casting process, while forged one involves heating a block of steel until it gets red hot. Subsequently, the forged steel is kept under high pressure to shape it in any desired form.

The manufacturing process of crankshafts also includes surface hardening and heat treatment techniques like carburising, nitriding etc., in order to enhance durability. Lastly, the choice of materials used for crankshaft construction depends on various factors such as operating conditions, the engine’s power output, and more.

How the Crankshaft Works

A crankshaft contains several parts that work in tandem to make a vehicle move. It has crankpins and cranks connected to connecting rods and vibration dampers that help mitigate crank thrusts. Below is a detailed description of how the crankshaft works in a 4-stroke engine.

Downward Motion Of Piston
In the first step, the engine piston moves from the top dead center to the bottom dead center in a downward motion. During this movement, the piston connected to the crankshaft through a connecting rod transfers its motion to it.

Motion Transformation
The next step involves transforming the piston’s linear motion into a rotary motion by the crankshaft. Furthermore, the crankshaft transfers this rotary motion to the camshaft after this transformation.

Compression
The camshaft receiving the rotary motion from the crankshaft facilitates the opening of the inlet valve. As a result, it allows the entry of air-fuel mixture into the engine combustion chamber. With the combustion chamber full, the piston moves from the bottom dead center to the top dead center in an upward motion, compressing the air-fuel mixture.
Also, as the piston moves upwards, the camshaft closes the exhaust and inlet values, completing the compression process. It also completes the first revolution of the crankshaft.

Ignition
The ignition phase is the next phase after the completion of compression. The heat released at the onset of the ignition phase pressures the piston into a downward stroke, also known as a power stroke. As this downward motion progresses, the piston also transfers its linear motion to the connecting rod affixed to the crankshaft.

Flywheel Motion
The crank has two ends, with one end connected to the flywheel. Hence, as the crank receives the linear motion of the piston, it converts it into a rotary motion. Subsequently, the crank transfers this rotary motion to the flywheel, which stores the motion to facilitate vehicular wheel movement.

Exhaust Stroke
This stage ends in the discharge of exhaust gasses from the combustion chamber due to the piston’s downward motion. Here, the camshaft receives the downward motion of the piston, consequently opening the exhaust valve.

Our Factory

Liubei engine factory, located in jinhua, zhejiang, is a leading global provider of automotive power solutions. Since its establishment, we have been committed to designing, manufacturing, and providing innovative, reliable, and efficient engine products, contributing to the development of the automotive industry.
We firmly believe that the engine is the heart of a car, driving every journey. Our mission is to provide excellent engine products and services to global customers through continuous technological innovation and process improvement, while committed to environmental sustainability.

Our Certificate

Our company has become one of the most competitive companies in the field of automotive engine parts, and has obtained iso/ts16949:2009 quality system certification

FAQ

Q: What is a crankshaft and its function?

A: The crankshaft is essentially the backbone of the internal combustion engine. The crankshaft is responsible for the proper operation of the engine and converting a linear motion to a rotational motion. Crankshafts should have very high fatigue strength and wear resistance to ensure long service life.

Q: What happens when crankshaft fails?

A: You may hear a knocking noise from the engine, or notice that the engine's oil pressure is low (from a gauge or warning light). In severe cases, the engine will simply stop running. If you notice any of these signs, pull your car over immediately, and shut off the engine. Do not try to drive it any farther.

Q: Why do you need a crankshaft?

A: There's a good reason for that: The crankshaft of a car is an essential component that ensures the engine's energy is effectively transformed into the motion propelling the vehicle forward. In other words, without a crankshaft, your car doesn't move.

Q: What happens when the crankshaft turns?

A: In an internal combustion engine, the piston is connected to the crankshaft through a connecting rod. This rod delivers the reciprocating motion to the crankshaft which transforms it into rotary motion to rotate the flywheel. After the flywheel rotates, the wheels of the vehicle begin to move.

Q: What turns the crankshaft in a car?

A: The engine crankshaft is positioned near the bottom end of the engine and is attached to the pistons via connecting roads – the downward movement of the pistons as a result of the combustion process causes the crankshaft to rotate.

Q: How do I tell if my crankshaft is bad?

A: You will know that it has become faulty when you experience symptoms of a bad crankshaft bearing that include knocking noises coming from the engine, metal shavings in the oil, low oil pressure, and crankshaft bearing noises.

Q: Can a crankshaft be repaired?

A: The only safe way to repair a crankshaft is if the damage is contained within the pins – you can grind them to undersize. Any other damage would, unfortunately, mean a new crankshaft is required. Bad news, but much better than the risk of blowing the whole engine.

Q: What causes a crankshaft to go bad?

A: The cause of broken crankshafts is rarely material fatigue brought about by extended use. Far more frequently, broken crankshafts can be attributed to: Mechanical overload of the crankshaft through abnormal combustion, water hammers, etc. Sudden jamming of the engine due to a faulty gearbox, loose counterweights, etc.

Q: Can I drive my car with a bad crankshaft?

A: Some common symptoms of a bad crankshaft position sensor are an illuminated check engine light, hard starting, and misfires. A bad crankshaft position sensor can prevent your vehicle from starting and leave you stranded somewhere, so it's best not to drive until you fix this part.

Q: How long can a crankshaft last?

A: Typically the life of the car. Unless there is an oil delivery issue inherent to the engine or for some other reason there is really nothing to cause them to fail before the rest of the engine does.

Q: Can you start a car without a crankshaft?

A: It is not possible. Car cannot run without a crank signal. It can run with a cam sensor.

Q: Does crankshaft affect performance?

A: Converting the reciprocating (up-and-down) motion of the connecting rods and pistons into rotating motion subjects the crank to harmful forces that can cause unwanted mechanical activity and prevent the engine from efficiently transferring power to the wheels.

Q: What is the main purpose of the crankshaft?

A: The crankshaft converts the force generated by the combustion in the engine into rotary motion. The linear upwards and downwards motion of the pistons is converted into a torque by the connecting rod and then transmitted to the fly wheel.

Q: What does a crankshaft look like?

A: Another long, metal rod, your crank shaft looks a little bit like the middle of a jenga game, with its webs, pins and connecting rod journals giving it an uneven appearance.

Q: Where is the crankshaft located on a car?

A: The crankshaft is located within the engine block and held in place via main bearings which allow the crankshaft to rotate within the block. The up-down motion of each piston is transferred to the crankshaft via connecting rods.

Q: Is the crankshaft connected to the transmission?

A: The crankshaft only connects to the transmission when the car is in gear and the clutch is engaged. If you press down on the clutch the crankshaft disconnects from the transmission. The transmission is connected to the output shaft, which is connected to the axles, which are connected to the wheels.

Q: Can you replace a crankshaft without removing the engine?

A: No, you can not change crank while engine in car. Trans must be removed etc and all go out the bottom, I wish it was easier but it is not and sorry for that and design. You need to remove the engine/trans etc out the bottom in order to change the crank.

Q: How often do you need to replace a crankshaft?

A: In general, however, a crankshaft should be reconditioned any time the bearings show signs of abnormal or increased wear, high oil temperatures/pressures or when early signs of machine failure are noticed.

Q: Does crankshaft affect transmission?

A: If it is sending the wrong signal, then the wrong sensors could fire, or the car could be in the wrong gear. This can cause a lot of damage to the engine and the transmission.

Q: What happens if your crankshaft goes out?

A: Engine misfires – if the crankshaft position sensor is not functioning properly, it can cause the engine to misfire. This can be due to an incorrect signal being sent to the computer, or no signal at all. Rough idling – another symptom of a faulty crankshaft position sensor is rough idling.

As one of the leading crankshaft manufacturers and suppliers in China, we warmly welcome you to buy high-grade crankshaft in stock here from our factory. All auto parts are with high quality and competitive price.

crank train, crankshaft