crankshaft—related to crank—is a mechanical part able to perform a conversion between reciprocating motion and rotational motion. In a reciprocating engine, it translates reciprocating motion of the piston into rotational motion; whereas in a reciprocating compressor, it converts the rotational motion into reciprocating motion. In order to do the conversion between two motions, the crankshaft has "crank throws" or "crankpins", additional bearing surfaces whose axis is offset from that of the crank, to which the "big ends" of the connecting rods from each cylinder attach.

This image represents the piston mechanism of a reciprocating combustion engine. The piston model accounts for the instantaneous torque transmitted to the engine crankshaft. The instantaneous torque enables you to model vibrations in the drivetrain due to piston revolution. The piston force follows from the cylinder pressure and cross-sectional area. The block obtains the combustion pressure from a lookup table parameterized in terms of the crank angle and, optionally, the crank angular velocity and engine throttle level.

Pistons within a sectioned petrol engine-


Animation of a piston system.

piston is a component of reciprocating engines, reciprocating pumpsgas compressors and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod. In a pump, the function is reversed and force is transferred from the crankshaft to the piston for the purpose of compressing or ejecting the fluid in the cylinder. In some engines, the piston also acts as a valve by covering and uncovering ports in the cylinder.


  • c is the crank length.

  • θ is the instantaneous crank angle.

  • r is the connecting rod length.


Cylinder bore-

internal diameter of the engine cylinder that the piston travels in. The default value is 0.10 m.

Piston stroke-

Distance between the top dead center and bottom dead center piston positions. The default value is 0.06 m.

Piston rod length-

Length of the connecting rod located between the engine piston and the crankshaft. The default value is 0.10 m.

Number of strokes per cycle-

Number of strokes required to complete one engine cycle. One stroke corresponds to a full extension or retraction of the engine piston. A typical automobile engine is based on a four-stroke cycle with induction, compression, power, and exhaust stages. The default value is 4.



  • avatar

    Arpit Vaishnav

    25/06/18 17:32

    Great Video Sagar i like your effort

  • avatar


    26/06/18 14:54

    Thanks to you Arpit sir

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