Ferrari 4RM dual gearbox all-wheel drive
Seen on: Ferrari FF
How it works: A two-speed automatic gearbox, called a Power Take-off Unit (PTU), sits on the front end of the engine, directly connected to the crankshaft and sending up to 20 percent of available power to the front axle. The PTU features a pair of electromagnetic clutches that operate as a torque vectoring system to actively split power between the front wheels.
But it doesn't stop there, because at the back of the engine is the seven-speed double clutch semi-automatic transmission that you'd expect to see on a Ferrari sending the other 80-plus percent of available torque to the rear axle where an electronic differential uses torque vectoring to split power between the rear wheels. Check out Ferrari's video to see the system in action.
The two-speed PTU features tall gearing, so its first gear operates through the driver's first and second shift on the rear gearbox, while the PTU's second gear operates through the driver's third and fourth. Beyond fourth gear, the PTU disengages and the FF becomes a purely RWD affair. Interestingly, the PTU features a reverse gear as well, so you even get AWD while going backward. With two gearboxes and two torque vectoring differentials, Ferrari's 4RM is likely one of the most complex all-wheel-drive systems on the road today. Interestingly, Ferrari also claims that its system is about 50 percent lighter than a standard AWD system.
May 23, 2011 7:45 PM PDT
Photo by: Ferrari
| Caption by: Antuan Goodwin
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