The principle of operation of reverse gear in an automatic transmission
Reverse gear in automatic transmissions (automatic transmissions) is used to move the car in the opposite direction. Its operating principle is as follows:
Switching to reverse mode
* When the driver moves the automatic transmission selector to the reverse (R) position, the transmission electronic control unit (ECU) receives a signal.
* The ECU activates an electromagnet which turns on the hydraulic valve.
Reverse hydraulic circuit operation
* The hydraulic valve directs transmission fluid to the appropriate passage in the hydraulic block.
* Fluid flows to the piston that controls the reverse clutches.
* The piston moves under fluid pressure, compressing the friction discs.
Reverse clutch
* Compressing the clutches causes them to engage with the transmission elements, creating a connection between the engine and the differential.
* Connecting the engine to the differential in the opposite direction causes the wheels to rotate in the opposite direction.
Direction of movement
* Reverse gear usually has a lower gear ratio than other gears, which increases torque to the wheels and makes it easier for the vehicle to move backwards.
* The wheels rotate backwards by a planetary gear set, which changes the direction of movement.
Disabling reverse gear
* To remove the automatic transmission from reverse mode, the driver moves the selector to another position.
* The ECU turns off the solenoid, closing the hydraulic valve.
* Fluid stops flowing to the piston and the reverse clutches open.