A crankshaft is one of the important components of a reciprocating engine. It acts as a link that connects the output section of the engine to the input section. A crankshaft converts the piston’s linear motion into rotary motion. Without it, a reciprocating engine cannot deliver power to the wheels and the vehicle can not move.
We have prepared a detailed guide on what a crankshaft is, how it works and its types.
What is a Crankshaft?
A crankshaft is a part of the car engine that delivers power to the gearbox. It is a mechanical rotating shaft that converts the reciprocal motion of a piston into rotary motion. 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.
The power cycle of different engines varies with different numbers of turns of the crankshaft. For 2-stroke engines, the power cycle is completed after one revolution of the crankshaft. In the case of a 4-stroke engine, it completes a power cycle after two revolutions of the crankshaft.
Let us now discuss the basic component and working principle of a crankshaft.
Components and Working of a Crankshaft
The following are the major parts of a crankshaft:
- Main Journal
- Connecting Rod Journal
- Crankshaft Lubrication
- Counterweights
- Thrust Washers
- Main Oil Seals
All the aforementioned components of a crankshaft play an important role in its working which is based on the crank mechanism.
Here’s a detailed description of its working.
A crankshaft consists of journals which rotate inside a bearing. There are two types of journals that are involved in the work: the main bearing journals provide an axis of rotation, and connecting rod journals or crank pins move the pistons through connecting rods. Both types of journals are linked together by crank webs.
The distance between the centre point of the main journal and the crankshaft pin is called the crank radius. It determines the range of the piston movement as the crankshaft rotates. The piston stroke is always twice the crank radius. The rear end of the crankshaft is connected to the flywheel, supported by a flange. The flange then carries the rotary motion to the wheels through transmission and final drive.
Types of Crankshaft
The piston is a part of the combustion chamber that transfer the load to the crankshaft. Since a crankshaft undergoes high bending and torsional forces, vibrations and pressures, it is manufactured from forged steel.
Following are the different types of crankshafts that can be used in an engine:
Cast Cranks
These are mostly found in in-line four engines and can be flame hardened to enhance wear resistance.
Forged Cranks
They come standard in some 16V engines and have a high clamping force.
Billet Cranks
This type has the lowest crankshaft machining time and requires minimal balancing.
Reasons for Crankshaft Damage
There are multiple reasons why a crankshaft might get damaged. Some of them are:
- When the engine is overheated, it melts the plastic covering of the crankshaft sensor. As a result, the sensor is unable to send the signal to the machine and the vehicle can not start.
- Loose wiring causes harness issues which damage the crankshaft. These voltage interruptions and wear and tear lead to crankshaft sensor failure.
- The timing belt around a crank gets affected due to frequent wear and tear. This also affects the small components of the crank. As a result, a broken timing belt leads to a damaged sensor.
Symptoms of a Crankshaft Position (CKP) Sensor Failure
The following are the symptoms that indicate the failure of the Crankshaft Position Sensor:
- Engine Stalling and backfiring
- Extensive noise
- Excessive engine vibration
- Cylinder misfire
- Engine knocking problems
Ways to Extend Service Life of Crankshaft
These are some of the effective methods that prolong the service life of a crankshaft.
- Prevent the engine from overheating
- Prevent the buildup of contamination
- Regular engine oil change
- Prevent mechanical overloading
- Proper lubrication of the crankshaft parts
This is all about the crankshaft and its working. It is an important part of the combustion engine that ensures the smooth running of a vehicle. Therefore, whether you own a used car in the UAE or drive the latest model, make sure to get these parts checked to avoid any car inconvenience or breakdown.
Stay tuned to UAE’s leading auto blog to learn more about car components and functionality.
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