- Straight-3
A straight-3 or inline-3 is an
internal combustion engine with three cylinders arranged in a straight line side by side.Most straight-3 engines employ a crank angle of 120° and are thus rotationally balanced; however, since the three cylinders are offset from each other, the firing of the end cylinders induces a rocking motion from end to end, since there is no opposing cylinder moving in the opposite direction as in a rotationally balanced straight six. The use of a
balance shaft in antiphase to that vibration produces a smoothly running engine.An exception to the 120° crankshaft can be found in some of the straight-3 engines made by motorcycle manufacturer
Laverda . In these engines, sometimes referred to as 180° triples, the outer pistons rise and fall together like a 360°straight-2 . The inner cylinder is offset 180° from the outer cylinders. In these engines cylinder 1 fires, 180° later cylinder 2 fires, and then 180° later cylinder 3 fires. There's no power stroke on the final 180° of rotation—much like a 4-cylinder engine that's missing the fourth cylinder.Automobile use
The smallest straight-3 engine was the 543 cc
Suzuki "F5A" used in the 1982 Cervo. Smart currently produces a diminutive 799 ccdiesel straight-3, the smallest ever. Most straight-3 engines fall below 1.2 liters, with a 1,198 ccVolkswagen unit seen as the largest petrol unit. A 1.8 L (1779 cc) diesel was produced byVM Motori to 1984Alfa Romeo 33 "1.8 TD", the largest straight-3 produced for automotive use. Straight-3 engine are also used in a some of Daihatsu cars. The Daihatsu Charade and the Cuore used or are still fitted with this engine type. The 3 cylinder 1.0 liter Daihatsu Diesel engine was also available with a turbo charger.Motorcycle use
4-stroke:
Aprilia ,Laverda , Triumph, Yamaha,BMW .The
Triumph Rocket III has a 2,294 cc straight-3 engine, currently the largest engine in a motorcycle being made by a major manufacturer.2-stroke :
Kawasaki,
Suzuki References
*http://www.laverdamania.com/millegb.htm
*http://www.autozine.org/technical_school/engine/smooth1.htm
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