The ZF 4 HP 16 is a 4-speed automatic transaxle designed for cars with front-wheel drive and a transversely mounted engine.
The transaxle has a hydrodynamic torque converter with a controlled slip lock-up clutch.
A planetary gear train establishes the mechanical gear ratios. The integral constant ratio can be adapted to the engines power output and the vehicles weight. The electronic-hydraulic control makes controlled power shifts and various shift programs possible. In selector lever position P, the output is locked mechanically.
The special feature of this transaxle is that it operates without freewheels. Shifting between individual gears takes place by means of overlapping clutch engagement and release.
The advantage of overlap shifting is as follows:
| • | The transaxle can be of more compact design and is lighter on account of the absence of freewheels and the lower number of shift elements. |
| • | Lower drag losses, i.e. higher efficiency |
| • | Lower peak torques acting on the components and driveline |
However, overlap shifting necessitates high-performance hardware and software, and precision engine signals.
