Seeing a crankshaft rotating may make you ask a question: what drives the crankshaft of an internal combustion engine?
The downward movement of the piston drives the crankshaft. The combustion process caused downward movement in the piston, which was transferred to the crankshaft via the connecting rod.
In my single-cylinder engine, when the conrod broke, the engine stopped rotating because no power was transferred to the crankshaft.
The crankshaft lacked the power from the piston through the explosion that forced the piston to move downward and caused steady rotation in the engine until the engine was shut down.
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Keep reading for more details.
What Moves The Crankshaft In An Engine
Seeing an engine rotating and running is something amazing to watch. Many wonder what keeps the crankshaft running, especially when the starter motor is no longer running.
In this article, you get the right answer on the crankshaft rotation and movement.
Initial crankshaft rotation started from the Kickstarter motor, but as soon as it began to rotate on its own, the piston’s downward movement was responsible for crankshaft rotation.
The crankshaft operation depends on the up-and-down movement of the piston. But what causes the downward movement of the piston?
The combustion that took place at the end of the power stroke forced the piston to go down, and that is the force that caused the crankshaft to keep rotating.
The crankshaft components, such as the crank pin, crank journal, and counterweight, rotate together with the crankshaft as the piston movement causes the rotation.
The crankshaft rotation makes power transmission possible in a car because the crankshaft transfers the rotation force to the gearbox via the clutch accessories and another rotary electric unit that makes the vehicle movement possible.
The piston’s downward movement is also responsible for the engine output generation. For the engine to generate maximum power, the crankshaft must rotate at a specific rpm to generate specific engine output.
That is why the crankshaft stops moving as soon as the piston stops. In the multiple-cylinder engine, the piston’s movement helps maintain balance because when some pistons are at the TDC, some are at the BDC. It is this principle that helps the whole engine to maintain balance and eliminate vibration.
From reading the article, you should have understood that the piston’s downward movement caused the crankshaft to keep rotating.
What Produces Power To Turn The Crankshaft
The combustion process produces the power to turn the engine.
The third phase of a four-stroke engine is a combustion chamber filled with an air-fuel mixture that detonates thanks to a spark (in gasoline engines) or self-detonation due to compression (in diesel engines ).
The explosion pushes the piston down again.
That is only possible in internal combustion engines because the combustion occurs in the combustion chamber.
Convert a flammable liquid into energy and transform said energy into heat and motion.
That is the magic internal combustion engines achieve, pieces of millimetric engineering that are part of our daily lives.
The pistons are responsible for moving the gases.
The vacuum they generate in the combustion chamber calls the mixture inside to compress and take advantage of the force of the explosion.
Its vertical movement pushes the crankshaft through the connecting rods and is converted into the energy that moves the vehicle.
What Transfers Power From The Piston To The Crankshaft
The connecting rod transmits the power from the piston to the crankshaft. The connecting rod serves as the pivotal element linking the piston and crankshaft.
As the name implies, the connecting rod connects two components: the piston and the crankshaft.
The connecting rod is shaped like a bar and has joints at both ends. It is that piece that connects the crankshaft with the piston to transmit movement, similar to what we do when pedalling a bicycle.
The main role of the connecting rod is to transfer the pressure produced by the gases on the piston to the crankshaft. The link in that chain converts reciprocating linear motion into uniform rotary motion.
This piece must withstand large traction and compression forces. That is why its design and manufacturing are so important for its correct operation, especially considering it is located in an area where lubrication is complicated.
What Is The Main Role Of The Crankshaft
The crankshaft is a fundamental part of internal combustion engines. It is a bar or axis formed by elbows or counterweights, and its operation is based on the connecting rod-crank mechanism.
It also receives other names such as crankshaft, crankshaft or motor shaft.
Its primary job is to change the pistons’ linear motion into a circular one. The connecting rods, which are connected to the pistons that move during combustion, are connected to the crankshaft. Other names for it are crankshaft, motor shaft, and crankshaft.
It is located inside the engine block; the crankshaft receives the linear movement of the piston through the connecting rod.
It transforms it into a circular movement, thus transmitting movement to the wheels.
Generally, the crankshaft is made of very resistant alloys, given the great effort they exert.
It has to meet certain characteristics to meet the speed, reliability and power needs of the engine in which it is installed.
Does The Crankshaft Drive The Transmission
Yes, the crankshaft drives the transmission. How? Although the crankshaft is not directly attached to the transmission, the crankshaft drives the clutch system via the flywheel and the drive shaft, also known as the propeller shaft, drives the transmission.
From the explanation, you can denote that the power to run the engine comes from the crankshaft.
That is the source of rotation in the engine. If there is no rotation from the crankshaft, there is no way the transmission can rotate, whether manual or automatic.
Although in automatic, there is no clutch; rather, what is available is a torque converter. The flywheel is attached to the torque converter rather than the clutch.
Another name for the gearbox is the transmission.
The gearbox is responsible for converting engine power into motion. With the help of the gear ix, the engine can run at efficient rpm regardless of the engine speed.
What Does The Crankshaft Drive
The answer to this question depends on the usage of the engine. The crankshaft drives the wheel through the transmission if the engine is in a car.
But if the engine is in a generator, the crankshaft drives the generator armature to produce current.
Let’s focus on the engine driving transmission or the gearbox.
The torque converter consists of a pump wheel, a stator and a turbine wheel.
There is oil in the torque converter used for power transmission. When the engine accelerates the pump wheel, oil is thrown against the blades, which drives the turbine wheel (and, therefore, the gearbox).
Whether directly or indirectly, the crankshaft is responsible for the wheel’s drive through the transmission.
Does The Crankshaft Drive The Pistons
Although the piston is attached to the crankshaft, the crankshaft does drive the piston; rather, the piston moves the crankshaft.
As mentioned above, the downward movement of the piston drives the crankshaft.
The crankshaft only drives the piston before the engine starts, when Kickstarter is rotating the engine. At that time, there was no combustion because the engine had not started. But as soon as the engine starts running on its own, the piston is driving the crankshaft, not the crankshaft driving the piston.
The crankshaft is the main rotating mechanism of the engine.
After converting the force from the connecting rod into torque, the crankshaft outputs the torque to drive the other engine parts. As a result, the journal surface needs to be wear-resistant, perform evenly, and have good balance, and the crankshaft needs to be strong and rigid enough.
What Moves The Piston Up
The crankshaft moves the piston up. That happens at the exhaust stroke. After the explosion, the piston forces the crankshaft to go down; the crankshaft returns the piston to the TDC position to push out the exhaust gases.
The relationship between the piston and the crankshaft is very cordial because the piston pushes the crankshaft downward while the crankshaft pushes the piston upward.
This way, the piston rises and falls in response to the explosions.
At the same time, the connecting rod transforms this type of movement into another suitable for moving the crankshaft, which transmits it to the rest of the vehicle’s direction, making possible the necessary movement during the engine running.
Final Thought
The crankshaft drive causes the upward movement of the piston.
The explosion in the combustion chamber pushes the piston downward and keeps driving the crankshaft.
Remember that the connecting rod transfers the power from the piston to the crankshaft. However, it would help if you also remembered that the crankshaft returns the piston to the upward position.
The crankshaft drives the engine’s wheel via the transmission and gearbox in manual.
The crankshaft also goes transmission via the clutch or torque converter.
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