Which engine has a long crankshaft?



The combustion of the fuel-air mixture generated in the engine generates power. The crankshaft converts this force into a rotary motion. That is done by converting the linear movement of the pistons that go over The connecting rod is passed into a torque and passed on to the flywheel.

The crankshaft has to withstand high loads. On the one hand, it is exposed to high stresses from bending and torsion. In addition, loads arise from torsional vibrations, since the crankshaft is constantly accelerated and braked in its rotary motion in jerks. Furthermore, the bearing points are subject to a high level of wear and tear.

Structure and components of the crankshaft

In order to be protected against wear and tear and stressful rotary movements, crankshafts must have a hard surface and a tough core. Crankshafts are therefore often forged. Alloyed quenched and tempered steel or nitrided steel are used as the starting material. The bearing journals of the crankshaft are also surface-hardened.

A crankshaft consists of the following components:

  • Shaft journal
  • Crank pin
  • Crank webs
  • Counterweights

Shaft journals run in the main bearings and define the axis of rotation of the shaft. Crank pins hold the connecting rods. Crank webs connect the crank pins with the shaft journals. The counterweights are used for balancing and are attached to the cheeks.

Design of the crankshaft

The design of the crankshaft is determined by the firing order of the engine, the number of cylinders, the engine design, the size of the stroke and the number of crankshaft bearings.

A variable compression can be achieved through a height-adjustable mounting of the crankshaft - for example by an eccentrically mounted crankshaft bearing. The advantage of variable compression is that fuel consumption is up to 25 percent lower in the partial load range.