Thursday, March 24, 2011
Ferrari's Cat Skinner
There are, idiomatically, many ways to skin a cat. There are also many ways to route power to all four wheels of a car. Many do it with a transfer case bolted to the transmission, some do it with electric motors, then there's Ferrari.
Ferrari does it with two transmissions.
Ferrari's new FF is remarkable for a number of reasons, but certainly one is the system they have dubbed "4RM" (for 4 ruote motrici - 4 wheel drive in Italian). Rather than worry about routing driveshafts all over the car and mucking up the underfloor, Ferrari mounted a second transmission directly to the front of the engine. It's a two-speed unit driven directly from the crank, and the FF relies on a pair of clutches to reconcile the drive ratio difference between the two-speed front and seven-speed rear transmissions. The twin clutches also allow the computer controlling the system to route different amounts of power to each of the front wheels to maximize performance in any given situation.
An animation of the system in action can be found here:
Winning all those F1 races certainly must be good for something, and Ferrari is no doubt quite good at making things like clutches, but designing a system that depends on two constantly-slipping clutches dealing with the 100 pound-feet of torque that can be sent up front will certainly put their engineering skills on display.
More photos, videos, and any other information you might be looking for about the Ferrari FF can be found at their site: http://www.ferrarifour.com/