Consultation on automatic transmissions

Hello everyone, I read a book and I'm left with the following questions, which I hope you can answer, as I'm not very familiar with this topic.

1- In cruise control, what is the function of the torque converter stator?

2- If the gear selector is in D with the brake pedal pressed, what does the computer do?

3- Regarding the BBS (Brake Brake System), when the brakes are not applied, is the voltage reaching the PCM (Powertrain Control Module) 0 volts?

4- The more I accelerate the engine, the lower the pressure in the automatic transmission will be?

5- If the engine temperature is below 70°C, does the PCM increase or decrease the shift speed?

6- Are there distributor valves in automatic transmissions, such as a 3-way, 2-position valve?

7- What are some other names for the manual shift valve?

I hope you can help me answer these questions. Greetings to the entire community.

Hey friend, I hope my answers can help you a little and not confuse you more, haha.

As you probably noticed in the book you read, one of the many differences between a standard and an automatic transmission is that: in a standard transmission, there's a mechanical coupling between the engine and the transmission through the clutch, while in an automatic transmission, the coupling is hydraulic. This hydraulic coupling takes place inside the torque converter.

The torque converter performs two phases: torque multiplier and hydraulic coupling. But there are converters that perform a third phase, which is mechanical coupling.


I hope I'm not confusing you more.

1. At cruising speed, the torque converter is in the hydraulic coupling phase; the stator directs the oil coming from the turbine.

2. When you shift the lever into D (with the brake pedal pressed, of course), you'll notice a feeling of the clutch engaging.
When you select D, the computer receives a signal from a sensor called TR. This energizes one or more solenoids (depending on the transmission) to direct oil flow to the first-gear clutch. Whether or not the brake pedal is pressed, these signals from the computer are already in place.

3. The voltage received by the computer from this sensor is indeed 0 volts.

4. Transmissions operate within a pressure range, which varies depending on the transmission. Accelerating slightly increases the pressure. For example, if a manual states that the pressure in D should be between 54 and 96 psi, a relief valve is in place to prevent excessive pressure. (Just like the engine oil pump or the fuel rail pressure regulator valve). Note, the pressure I gave you there is an example of how it will operate in D within that range, without exceeding 96 psi or falling below 54 psi for proper transmission function.

5. That depends on the driving style. For that, the computer needs to know the values ​​from engine sensors like TPS, ECT, MAF, MAP, CKP, and VSS.


6. Yes, there are manual valves, but each transmission is different. You can find simple transmissions with a single valve body and more complex ones with multiple valve bodies.

7. At least, that's the only name I know it by.

Regards, and remember that saying thanks costs nothing.