Editing Crankshaft (section)

===Bearings===
{{main|Main bearing}}
The crankshaft is able to rotate in the [[engine block]] due to the 'main [[Bearing (mechanical)|bearings]]'. Since the crankshaft is subject to large horizontal and [[Torsion (mechanics)|torsional forces]] from each cylinder, these main bearings are located at various points along the crankshaft, rather than just one at each end.<ref>{{cite web |title=Flat-Plane Cranks, Part 2 — Calculating Crankshaft Secondary Forces |url=https://www.enginelabs.com/tech-stories/flat-plane-cranks-part-2-calculating-crankshaft-secondary-forces/ |website=EngineLabs |access-date=28 August 2022 |date=20 January 2022}}</ref> The number of main bearings is determined based on the overall load factor and the maximum engine speed. Crankshafts in [[Diesel engine|diesel engines]] often use a main bearing between every cylinder and at both ends of the crankshaft, due to the high forces of combustion present.<ref>{{cite book |last1=Bosch |first1=Robert |title=Automotive Handbook |date=2004 |publisher=Robert Bosch |isbn=978-0-8376-1243-0 |page=465 |url=https://books.google.com/books?id=_t1oPwAACAAJ |access-date=28 August 2022 |language=en}}</ref>

Flexing of the crankshaft was a factor in [[V8 engine]]s replacing [[straight-eight engine]]s in the 1950s; the long crankshafts of the latter suffered from an unacceptable amount of flex when engine designers began using higher [[compression ratio]]s and higher engine speeds (RPM).<ref>{{cite web |title=A Brief History Of The Straight-Eight Engine – Carole Nash |url=https://www.carolenash.com/news/classic-car-news/detail/a-brief-history-of-the-straight-eight-engine |website=Carole Nash UK |access-date=28 August 2022 |language=en}}</ref>