(Automatic Transmission, Basic Function - GF27.00-P-9901A)
Model all with transmission 725
Overview
This document contains information on:
- General
- Function
General
Combustion engines operate in a limited rpm range. The automatic transmission converts the engine torque into the tractive force required by the wheels to overcome motion resistance.
The automatic transmission is an entirely electronically controlled automatic transmission with nine forward gears and one reverse gear.
The gear ratios for the gear ranges are achieved by planetary gear sets. In the automatic transmission, all transmission functions and components are combined in one assembly module.
Function
The fully integrated transmission control controller unit located in the automatic transmission minimizes interfaces to the subharness in the vehicle.
Using the fully integrated transmission control provides the following additional advantages:
- High electromagnetic compatibility (prevention of interaction between multiple electronic components)
- Fast current control as well as compensation for on-board electrical system fluctuations (increasing shift quality)
- Accurate determination of measurements relevant to shift operations and faster evaluation of the measured values
Increased service life, reduced fuel consumption and maximum gearshift comfort can be achieved with the following:
- Transmission set-up with nine gears and gear ratio spread of 9.15
- Optimized transmission components
- Reduction of working pressure
- Software with additional comfort and dynamic functions
- Actuation concept with two oil pumps
The transmission can be subdivided into the following assemblies:
- Torque converter with torsional damper, centrifugal pendulum and torque converter lockup clutch
- Oil pump (primary pump) for generating the necessary oil pressure and for reliable lubrication of the shift elements and bearing points
- Electrical auxiliary oil pump for generating required oil pressure, for guaranteeing lubrication of shift elements and bearing points at engine OFF and for supporting the primary pump
- Transmission housing with mechanical transmission components (planetary gear sets, electrohydraulically operated park pawl, multidisk clutches and multidisk brakes)
- Fully integrated transmission control controller unit with integrated fully integrated transmission control unit
In terms of design, a distinction is made between the following variants:
- Automatic transmission with torque converter and integrated centrifugal pendulum
- Automatic transmission with torque converter and engine separator clutch
- Automatic transmission with wet clutch
Example illustration of automatic transmission with torque converter and integrated centrifugal pendulum
Example illustration of automatic transmission with torque converter and engine separator clutch
Example illustration of automatic transmission with torque converter and integrated centrifugal pendulum
Example illustration of automatic transmission with wet clutch
| Additional basic functions | |||
| Gearshift system, basic function | GF27.60-P-1002B | ||
| Fully integrated transmission control controller unit, basic function | GF27.60-P-2003A | ||
| Torque converter lockup clutch control, basic function | GF27.20-P-1001A | ||
| Automatic transmission oil supply, basic function | GF27.57-P-1003A | ||
| Transmission cooling, basic function | GF27.55-P-1000B | ||
| Power transmission, basic function | GF27.10-P-9901B | ||
| Park pawl, basic function | GF27.10-P-9900A | ||
| Electric machine, basic function | Electric vehicles and hybrid vehicles | GF08.10-P-2000A |