During sudden braking, the following processes occur in an automatic transmission:
1. Increase in system pressure: The hydraulic fluid pressure in the automatic transmission increases sharply as the brake system transmits force to the gearbox.
2. Torque converter actuation: The torque converter engages the vehicle’s wheels with the engine. When braking sharply, the wheel speed drops sharply, which increases the load on the torque converter, which is activated to protect the engine.
3. Downshifting: The automatic transmission automatically downshifts to increase braking torque and slow down the vehicle. This occurs thanks to the flow of hydraulic fluid, which is directed to the appropriate position in the control unit.
4. Lockup torque converter clutch: Some types of automatic transmissions have a torque converter clutch that locks under certain conditions to reduce slip losses. Under hard braking, the clutch can release to provide smoother braking.
5. Valve Actuation: Automatic transmission valves play a critical role in controlling the transmission. During heavy braking, the valves redirect the flow of hydraulic fluid to change gears and control system pressure.
6. Gear retention: In some cases, the automatic transmission can maintain the current gear even if the vehicle speed has decreased. This is done to prevent gear changes that could destabilize the vehicle.
Heavy braking can put significant stress on the automatic transmission, so it is important to service the transmission in accordance with the manufacturer’s recommendations. If sudden braking occurs frequently, this can lead to wear and problems with the automatic transmission.