From Hellforleathermagazine.com (they have great pics , and the patent:
http://hellforleathermagazine.com/2011/04/honda-motogp-transmission/
Last month we connected the dots, concluding that Honda must be using a gearbox which could deliver the benefits of DCT using a single clutch. We presented two gearboxes — one made by Zeroshift, the other Xtrac — which claim similar benefits. Both of those work by using a ratchet system between each gear which allows two gears to be selected at the same time, but with only one engaged. When the transmission is shifted, the engagement of the next gear causes the disengagement of the previous one.
Well, it turns out that the mechanism isn’t between the gears, it’s underneath it. The truth about how this system works is even more awesome than I imagined.
The transmission’s 12 gears (it takes 12 to make six speeds) are lined up six per shaft, with nothing in between them. The gears on the main shaft (or input shaft) are fixed and all rotate at the same speed. The gears on the countershaft (or output shaft) freewheel. This is where things get weird. Inside the countershaft is another shaft which takes on the function of the shift forks in a conventional transmission. Operated by the shift drum, it moves 12 rods that have small eccentrics cut into them. In turn, those rods move very small pins which ride in holes drilled into the wall of the countershaft. Those tiny pins operate a set of four spring-loaded rocker arms housed inside each gear. When the pins are forced outward, they move the rocker arms up. The rockers catch the underside of the gear, thus completing a shift.
No clutch trickery is necessary, the engine power just needs to be killed for the time it takes to complete a shift.
http://hellforleathermagazine.com/2011/04/honda-motogp-transmission/
Last month we connected the dots, concluding that Honda must be using a gearbox which could deliver the benefits of DCT using a single clutch. We presented two gearboxes — one made by Zeroshift, the other Xtrac — which claim similar benefits. Both of those work by using a ratchet system between each gear which allows two gears to be selected at the same time, but with only one engaged. When the transmission is shifted, the engagement of the next gear causes the disengagement of the previous one.
Well, it turns out that the mechanism isn’t between the gears, it’s underneath it. The truth about how this system works is even more awesome than I imagined.
The transmission’s 12 gears (it takes 12 to make six speeds) are lined up six per shaft, with nothing in between them. The gears on the main shaft (or input shaft) are fixed and all rotate at the same speed. The gears on the countershaft (or output shaft) freewheel. This is where things get weird. Inside the countershaft is another shaft which takes on the function of the shift forks in a conventional transmission. Operated by the shift drum, it moves 12 rods that have small eccentrics cut into them. In turn, those rods move very small pins which ride in holes drilled into the wall of the countershaft. Those tiny pins operate a set of four spring-loaded rocker arms housed inside each gear. When the pins are forced outward, they move the rocker arms up. The rockers catch the underside of the gear, thus completing a shift.
No clutch trickery is necessary, the engine power just needs to be killed for the time it takes to complete a shift.
