Editing Straight-three engine (section)

== Design ==
[[File:Reihenmotor Drei Zylinder.gif|thumb|four stroke Straight-three engine with firing order 1-3-2]]
A [[crankshaft]] angle of 120 degrees is typically used by straight-three engines,<ref>{{Cite web|url=https://www.carthrottle.com/post/heres-the-problem-with-three-cylinder-engines/|title=Here's The Problem With Three-Cylinder Engines|website=Car Throttle|language=en|access-date=2019-12-03}}</ref> since this results in an evenly spaced [[Firing order#Firing interval|firing interval]]. Another benefit of this configuration is perfect [[Engine balance#Primary balance|primary balance]] and [[Engine balance#Secondary balance|secondary balance]], however an end-to-end [[Couple (mechanics)|rocking couple]] is induced because there is no symmetry in the piston velocities about the middle piston. A [[balance shaft]] is sometimes used to reduce the vibrations caused by the rocking couple.

Other crankshaft angles have been used occasionally. The 1976–1981 [[Laverda Jota]] motorcycle used a 180 degree crankshaft, where the outer pistons rise and fall together and inner cylinder is offset from them by 180 degrees. This results in three power strokes evenly-spaced at 180 degrees each, and then no power strokes during the final 180 degrees of crankshaft rotation. The 2020 [[Triumph Tiger 900 (2020)|Triumph Tiger 900]] motorcycle uses a "T-Plane" crankshaft where the crankshaft throws are at 90 intervals, such that the throws for cylinders 1 and 3 are separated by 180 degrees (therefore the three throws together forming a "T" shape when viewed from the end).<ref>{{cite web |title=TIGER 900 ENGINE & CAPABILITY |url=https://www.triumphmotorcycles.co.uk/motorcycles/adventure/tiger-900/engine-and-capability |website=Triumph Motorcycles UK |access-date=10 February 2020}}</ref><ref>{{cite web |last1=Cameron |first1=Kevin |title=Triumph's New T-Plane Firing Order Explained |url=https://www.cycleworld.com/story/bikes/triumphs-new-t-plane-firing-order-explained/ |website=Cycleworld |access-date=10 February 2020}}</ref>