COUNTERROTATING CRANKS

Motorcycle News (UK) - - This Week -

In a con­ven­tional mo­tor­cy­cle en­gine, the crank­shaft (which con­verts the lin­ear mo­tion of the pis­tons into a ro­ta­tional mo­tion) moves in the same di­rec­tion as the wheels. Mo­tor­cy­cles have used this con­fig­u­ra­tion since the be­gin­ning be­cause it’s sim­ple, light­weight and ef­fi­cient. But all those ob­jects ro­tat­ing in the same di­rec­tion have a large in­er­tial mass, which can make it dif­fi­cult to turn and give a bike the ten­dency to wheelie un­der ex­treme ac­cel­er­a­tion. A counter-ro­tat­ing crank­shaft spins in the op­po­site di­rec­tion to the wheels. This means the gy­ro­scopic forces of the crank and wheels can­cel each other out to a cer­tain ex­tent, negat­ing the typ­i­cal turn­ing and wheelie ef­fects. The counter-ro­tat­ing crank first hit the big time in 1980s, when it fea­tured in Honda’s NSR500 but it’s back un­der the spot­light af­ter Du­cati used the tech­nol­ogy in the all-new Pani­gale V4. As with most tech­nol­ogy there are draw­backs. An ex­tra gear is re­quired in the gear­box, to turn the back­wards mo­tion of the crank into for­wards mo­tion at the wheels. This adds weight, com­plex­ity and ex­pense to the fin­ished prod­uct, as well as steal­ing a bit of en­gine power.

Newspapers in English

Newspapers from UK

© PressReader. All rights reserved.