Automatic transmission (automatic transmission) Mercedes-Benz 124
The Mercedes-Benz 124 automatic transmission is a complex system that ensures smooth gear shifting and vehicle control. It consists of the following main components:
1. Torque converter:
* Located between the engine and gearbox.
* Transmits torque from the engine to the gearbox using the principle of hydrodynamic coupling.
* Controls gear shift speed and ensures smooth starting.
2. Planetary gearbox:
* Contains multiple gears that form different gear combinations.
* Allows the transmission to shift between different gear ratios.
3. Hydraulic Control Unit (HCU):
* The brain of the automatic transmission, controlling the torque and intensity of gear shifting.
* Uses electronic signals and fluid pressure to control the operation of valves and actuators.
4. Valves and actuators:
* Control the flow of fluid through the gearbox to engage and disengage various gears.
5. Sensors:
* Provides the HCU with the information needed to make shift decisions.
* Includes speed, throttle position and transmission fluid temperature sensors.
Operating principle of the Mercedes-Benz 124 automatic transmission:
1. Pulling Off: When the driver moves the gearshift lever to the ‘D’ position, the HCU sends a signal to the valves to engage the low ratio gear. The torque converter multiplies torque at low revs for smooth traction.
2. Shifting: As vehicle speed increases, the HCU uses sensors to determine the optimal shift point. It sends signals to the valves to smoothly shift gears to higher or lower ratios.
3. Anti-slip: The HCU also controls torque converter lock-up to prevent slip and improve efficiency at higher speeds.
4. Kickdown: If the driver presses the accelerator pedal hard, the HCU recognizes this as a need to downshift to accelerate quickly. It sends a signal to the valves to perform a so-called ‘kickdown’ (quick downshift).
5. Park Mode (P): When the gear shift lever is moved to the ‘P’ position, the HCU activates a mechanical lock on the transmission output shaft, preventing the vehicle from moving.
The Mercedes-Benz 124 automatic transmission is known for its smooth gear shifting, reliability and durability. To ensure optimal performance, it is important to perform regular maintenance, including changing the transmission fluid and filter.