Planetary Gears
WARNING: This page is about a different car, the 2006 Suzuki Verona. However, it is still accessible from the selected car via links, so may be relevant.
The ZF 4HP 16 automatic transaxle is equipped with a sun gear, 4 planetary gears, planetary carrier, ring gear. Each gear is located one directly behind the other and are linked together. In other words, front ring gear is permanently linked to rear planet carrier, front planet carrier is linked to rear ring gear.
The individual gear ratios are obtained by linking together the gear set elements in different ways by means of clutches and brakes.
On the 4HP 16, the power flow is directed into the planetary gear set via rear planet carrier or rear sun gear, or via both simultaneously, depending on the gear in question. The output is always via the front planet carrier.