Gearbox
Gearbox |
The automatic transmission has 4 planet gears with associated clutches, brakes and freewheels. It has two shafts (primary and secondary shaft). Two of the 4 planet gears, P1 and P2, are fitted to the primary shaft.
P3 and P4 are mounted on the secondary shaft
The power from the primary shaft is transmitted to the secondary shaft via two intermediate gears. From the secondary shaft the power is then transmitted to the final drive via two final drive pinions, one driving and one driven.
The transmission has 5 forward gears and one reverse.
There is normally some slippage in the torque converter. This slippage is proportional to the increase in torque that it brings about. To reduce fuel consumption, a lock-up clutch on 3rd, 4th and 5th gears is used (V6 petrol: 4th and 5th gears only). This clutch is located in the torque converter. When engaged, the clutch provides direct drive through the torque converter.
To allow engine torque to be utilized efficiently a certain amount of slippage is allowed in the lock-up clutch. The purpose of this function is to save fuel. When the desired torque is moderate (small accelerator travel), the lock-up clutch slips within certain limits (50 - 200 rpm). This means that it is not necessary for the transmission to shift down.