If Audi�s Multitronic is an evolution of the conventional CVT, Nissan�s Extroid is obviously a revolution. Instead of using a belt or chain as the media for varying transmission ratio, it uses two pairs of rollers. The rollers link between the input disc (which connects the crankshaft) and output disc (which connects the driveshaft). By varying the angle of rollers, different transmission ratio can be obtained. For example, for "low" gearing ratio, the rollers meet the input disc near its inside diameter, but meet the output disc near its periphery; thus the output disc turns much slower than the input disc. The overall ratio range is 4.4:1. Compare with belt or chain, the solid rollers can withstand much higher torque. Moreover, since the input and output disc are located at the same axis, it is able to be packaged in a longitudinal gearbox and drive the rear wheels. In fact, it is already driving the Cedric / Gloria in Japan, handling the massive 286 lbft of torque from the turbocharged VQ6. The rollers are actuated by electro-hydraulic. However, the rollers are not directly contact with the input / output disc. A specially developed viscous oil provides the traction between them while reduce friction and wear. Like other modern CVTs, it also provides 6 artificial sequential ratios for more driver involvement. Kenichi 94' Sentra E Ga16DE www.importpartsplus.com ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Go to <http://www.escribe.com/automotive/sml/> for the list archives.
