Which statement about the transmission hydraulic system is correct?

Which statement about the transmission hydraulic system is correct?

• A. All hydraulic circuits are fed by the main pressure circuit
• B. The hydraulic system prioritizes filling the torque converter because the converter works only when it is full of fluid
• C. Both statements are correct
• D. Neither statement is correct

Answer: (C)

In a transmission hydraulic system, the pump creates main line pressure that feeds most hydraulic functions such as gear changes and clutch or brake servo actuation. This pressure is distributed through the valve body and often through a priority or regulator arrangement so that essential circuits receive pressure first, including the path that fills the torque converter. Keeping the torque converter primed is important because the converter must be filled with transmission fluid to transmit torque effectively and to prevent air pockets that could cause poor lubrication or overheating. The system therefore prioritizes filling the torque converter to ensure immediate, smooth torque transfer when moving the vehicle, while still supplying the other hydraulic circuits from the same main pressure source. So both ideas—that all hydraulic circuits are fed from the main pressure and that the torque converter is filled promptly—are correct.

In a transmission hydraulic system, the pump creates main line pressure that feeds most hydraulic functions such as gear changes and clutch or brake servo actuation. This pressure is distributed through the valve body and often through a priority or regulator arrangement so that essential circuits receive pressure first, including the path that fills the torque converter. Keeping the torque converter primed is important because the converter must be filled with transmission fluid to transmit torque effectively and to prevent air pockets that could cause poor lubrication or overheating. The system therefore prioritizes filling the torque converter to ensure immediate, smooth torque transfer when moving the vehicle, while still supplying the other hydraulic circuits from the same main pressure source. So both ideas—that all hydraulic circuits are fed from the main pressure and that the torque converter is filled promptly—are correct.