Editing Connecting rod (section)

=== Fork-and-blade rods ===
[[File:Forked connecting rods (Autocar Handbook, 13th ed, 1935).jpg|thumb|upright|Fork and blade rods]]
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Fork-and-blade rods, also known as "split big-end rods", have been used on [[V-twin engine|V-twin]] motorcycle engines and [[V12 engine|V12]] aircraft engines.<ref>{{cite web |title=Drysdale Godzilla V-Twin |url=https://thekneeslider.com/drysdale-godzilla-v-twin/ |website=thekneeslider.com |access-date=26 September 2019}}</ref> For each pair of cylinders, a "fork" rod is split in two at the big end and the "blade" rod from the opposing cylinder is thinned to fit into this gap in the fork. This arrangement removes the [[couple (mechanics)|rocking couple]] that is caused when cylinder pairs are offset along the crankshaft.

A common arrangement for the big-end bearing is for the fork rod to have a single wide bearing sleeve that spans the whole width of the rod, including the central gap. The blade rod then runs, not directly on the crankpin, but on the outside of this sleeve. This causes the two rods to oscillate back and forth (instead of rotating relative to each other), which reduces the forces on the bearing and the surface speed. However, the bearing movement also becomes reciprocating rather than continuously rotating, which is a more difficult problem for lubrication.

Notable engines to use fork-and-blade rods include the [[Rolls-Royce Merlin]] V12 aircraft engine, [[Electro-Motive Diesel|EMD]] two-stroke Diesel engines, and various [[Harley-Davidson engine timeline|Harley Davidson]] V-twin motorcycle engines.