Audi A4

since 1994 of release

Repair and car operation



A4 Audi
+ Running gear
+ Regular servicing
+ Engines
+ Turbo-supercharging
+ exhaust System
+ cooling System
+ Fuel tank and fuel pump
+ Air filter and absorption channels
+ injection System
+ Coupling
- Transmission and main transfer
   Mechanical transmission
   Noise in a transmission
   Automatic transmission
   Electronic control by a transmission
   Main transfer
   Power shafts
   Check of cuffs of power shafts
   The help at malfunctions
+ Suspension bracket of wheels and steering
+ Brakes
+ Wheels and tires
+ Electrotechnical equipment
+ ignition System
+ Lighting
+ Alarm equipment
+ Tools and devices
+ Heating and ventilation
+ body Details
+ Salon
Search of malfunctions
Technical characteristics





Automatic transmission

In Audi A4 two various models of an automatic transmission are used for installation: first, developed VW «AG-4» transmission for the four-cylinder engine without a turbo-supercharging, secondly, designed ZF a transmission of «5 HP 18» for the six-cylinder engine. As it is already clear on designation, it is a question in one case of a four-speed transmission, in other case – about five-step.

Both transmissions cope in the electronic and hydraulic way, and this management works depending on various input parameters (number of turns of the engine, speed of movement, loading and so forth) when the following transfer joins. Besides, management distinguishes a manner of driving of the driver and establishes gear shifting points from "sports" to "economic", thus it is not necessary to put in action any switch. Everything the system as a whole is called as DSP – Dynamische Schalt-Programm (the dynamic program of gear shifting). Besides, at a choice of transfer the land relief is considered – i.e. automatic equipment chooses a mode of the gear shifting different from movement on the mountain road on the equal road.

Basic principles of functioning

The main link of all automatic transmissions are so-called planetary sets. They consist of a gear wheel round which three other gear wheels rotate. From above the ring with an internal teeth is put on. Each pair from these elements is connected in a set of gear gear wheels and forms an own small two-speed transmission. In these transmissions the way of their switching is ingenious. Switching of transfer is carried out at the expense of keeping or liberation of details of a planetary set. It becomes without interruption of a stream of force. Keeping and liberation provide lamellar couplings and lamellar brakes with a hydraulic drive.

For receiving a multistage transmission two planetary sets are consistently connected. At the correct arrangement of transfers it is formed four - or a five-speed transmission with backing transfer. Coordination of work of sets of gear wheels is provided with transmission management.

Torque hydrotransformer

In the photo of the hydrotransformer of a torque in a cut blades of the turbine and a directing wheel are visually shown. The arrow indicates a frictional facing of coupling of the hydrotransformer, which – except those cases when ATF cold, – since high speeds is switched to rigid transfer of force not to allow "gap".

Transfer of force of the engine to a transmission is carried out by means of liquid. The engine actuates the turbine in the torque hydrotransformer. Liquid in the hydrotransformer, given to rotation, by means of the scapular directing device located between them can actuate also the wheel of the turbine connected to a transmission. Between the turbine rotating according to turns of the engine, and a turbine wheel on a transmission entrance always there is a distinction among turns. In a start of motion it the biggest, in process of increase in speed the difference in number of turns between the turbine of the pump and the transmission turbine decreases more and more. But in a traditional automatic transmission still there is some "gap". In our transmissions the torque hydrotransformer перемыкается in a range of the 3rd and 4th transfer and to the 4th and the 5th, i.e. between the engine and an automatic transmission dominates rigid connection. It allows to reduce fuel consumption.