The diesel engines are units having the ability to convert the forces developed within the cylinders as a result of combustion of fuel into energy of mechanical type. This type of engine has several parts that are distributed to be able to transform the alternative linear movement into a uniform circular movement , one of them is the crankshaft .

What is the crankshaft?

The crankshaft or crankshaft is an axis that has a series of elbows and counterweights that vehicles have and that has a principle based on the connecting rod-crank mechanism, transforming the reciprocating rectilinear movement into a type of circular movement .

  • Crankshaft Characteristics
  • Types
  • Crankshaft parts
  • How does it work
  • What is it for
  • Breakdowns
  • Crankshaft maintenance
  • Importance

Crankshaft Characteristics

The main characteristics that can be found in a crankshaft are the following:

  • The crankshaft is located inside the engine .
  • It is a piece that transforms the rotary movement into a linear type movement .
  • It is attached to the connecting rods , below the connection between the pistons.
  • It can be constructed of different materials and this will depend on the size of the crankshaft and the speed and power of the engine.
  • It has a great resistance to avoid cracks due to combustion.
  • Its coefficient of friction is quite small in order to prevent the part from wearing excessively.
  • They are provided with a thermal treatment in order to improve their mechanical characteristics and elasticity .
  • It has a very good ductility .


There are several types of storks which, generally , are made up of cylinders. The number of these can vary and the choice of a certain type of crankshaft is made taking into account technical and economic reasons . The types of storks that can be found are the following:

  • Single-cylinder crankshafts: it has its cranks made up of two arms, the crankpin and the connecting rod.
  • In-line, opposite, and V- cylinder engine crankshafts : consist of the same number of crankshafts and cylinders. The V-engine can only be found half of the cylinders and cranks.

Crankshaft parts

The parts of a crankshaft are as follows:

  • Axis : the axis is the part that serves as a guide for the complete rotation of the entire piece.
  • Supports : the supports are in charge of making a turn on the crankcase and receiving different heat treatments to achieve greater resistance that makes possible a better precision and tolerance.
  • Crank pins : these pieces have the function of supporting the rotation that occurs in the cranks.
  • Arms : they are in charge of joining the crank pins and the supports.
  • Counterweights : these pieces make it possible to reduce the irregularities that are produced by the movements of the shaft.

How does it work

As the vehicle starts, the fuel inside the combustion chamber causes an explosion that causes the piston to move straight . This movement is then transmitted to the connecting rod , which is attached to the crankshaft . When the movement reaches this piece, the rectilinear movement is transformed into one of the rotary or circular type , and this is given in a uniform way. The crankshaft has several flywheels and counterweights that are responsible for reducing the irregularities produced by the axis of movement, thus improving the maximum amount of energy received.

What is it for

The crankshaft is considered one of the most important parts in a vehicle and in internal combustion engines . It serves to transform the reciprocating linear movement that occurs in the piston and that is also generated by the pressure that comes from the combustion gases into a circular motion of a uniform type .


There are several breakdowns that can occur in this important mechanical part. One of them is due to a malfunction in the vehicle’s engine , which can lead to a large mechanical overload of the crankshaft, mainly due to failures that occur in combustion . It can also be due to sudden engine stalling or excessive torsional vibrations .

The crankshaft may be damaged because the material is weakened and that the trunnions of the bearing are reduced in size, also mechanical damage that can occur in the shaft are a cause for the part to fail. Another very common fault are errors in terms of assembly and daily use of the vehicle, as this can lead to loss of hardness in the bearing journals. The tops of the main bearing and the connecting rod are assembled with when twisting , also can generate faults on the crankshaft and the use of parts or undue old tighten.

Crankshaft maintenance

Several aspects must be taken into account to give the crankshaft a good maintenance. Among them are mentioned the following:

  • Keep a sufficient quantity of oil in the engine , always following the instructions given by the manufacturer.
  • Do not use oils that are dirty or old .
  • Use of a cooling agent or fuel to avoid contamination of the oil.
  • Prevent the presence of faults in the circuits of the oil to avoid problems of pressure. These failures include, for example, a damaged oil pump, abnormal oil pressure, clogged pipes and channels.
  • Maintain a suitable engine oil temperature to prevent the lubricating film from breaking down.


The crankshaft is a very important element of the engine and therefore of the vehicle. This part is in fact considered fundamental because if the movement that occurs in the piston cannot be transformed into a circular movement , the main function of the crankshaft, and if it cannot reach the gearbox , the wheels of the vehicle could not function. .

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