Imagining a reciprocating engine without a crankshaft is impossible. A crankshaft converts reciprocating motion from the piston and connecting rod into rotary motion, which is then used to rotate the propeller assembly of an aircraft. A crankshaft consists of one or more cranks placed at specific lengths where the piston is mounted. The crankshaft is placed in the crankcase on a longitudinal axis supported by a bearing
between each throw.
Crankshafts need to be extremely strong for proper energy conversion and reliability, so they are often forged using some of the strongest alloys, such as chromium nickel molybdenum steel. They can be constructed in two ways, using either single-piece or multi-piece construction methods. Furthermore, the number of throws in a crankshaft depends on the engine. For instance, if the engine is a single row type, then a single-throw crankshaft will be used. Meanwhile if the engine is a twin-row type, then a two-throw crankshaft will be applicable. Similarly, there are four-throw and six-throw crankshaft types available for four-cylinder horizontally opposed engines, four-cylinder inline engines, six-cylinder inline engines, 12-cylinder V-type engines, and six-cylinder opposed engines, respectively. Moreover, the crankshaft is a significant part of the reciprocating engine. Irrespective of the number of throws, every crankshaft has three crucial components: a journal, crankpin, and crank cheek. Apart from these, counterweights and dampers are attached to the crankshaft.