Worlds fastest street car

"Like automatic transmissions, Lencos employ planetary gearsets to handle massive amounts of torque. Three components are in constant mesh--the sun gear, three pinion gears, and the ring gear, so power is spread out over a much larger area than in a cluster gear transmission. A Lenco is still considered a manual transmission and requires a clutch between the engine and transmission. The clutch is only used during starting and stopping, though. This is a huge performance advantage--you can shift a Lenco at full-throttle without ever lifting off the gas. Lenco also makes the Lencodrive, a manumatic transmission that uses a torque converter in place of a clutch. There is no third pedal, but the driver still has to shift the gears manually.

Several different gear ratios are possible out of a single planetary gearset, and Lencos are designed to run two speeds out of a single case: one reduction (the ratio depends on the gears you choose) and 1:1 direct drive. Multiple speeds are possible by stacking cases together. If you want a three-speed transmission, you need two cases. If you want four speeds, you need three cases, and so on. Remember, each case has two speeds, but direct drive in one case transfers the power to the low ratio of the case behind it until there are no more cases to shift into.

Though the operation sounds confusing, it's actually quite simple and brilliant. Starting from a stop, each case is essentially in first gear--their low ratio. When the driver engages the clutch, engine power turns the ring gear in the first case (though the ring gears in all the cases are turning as well). The sun gear is held by the overrunning clutch, so the planetary carrier is the output. When the driver pulls the shift lever, he's actuating the multiplate clutch housed in a hub on the planetary carrier. When this clutch in engaged, the input (the ring gear) and the output (the planetary carrier) are now locked together and the whole assembly turns at a 1:1 ratio.

Sumek tells us that contrary to popular belief, you can drive a Lenco on the street. It upshifts and downshifts just fine. The only driveability issue to be aware of is that because of the way the overrunning clutch works, there is no engine braking unless all the cases are shifted into direct drive."
from: http://www.carcraft.com/techarticles/ccrp_0904_inside_a_high_performance_drag_race_manual_transmission/lenco_racing_transmissions.html