The ______ circuit can be used to raise or boost main or control pressure in automatic transmissions.

The ______ circuit can be used to raise or boost main or control pressure in automatic transmissions.

• A. throttle or modulator
• B. lubrication
• C. converter-out
• D. governor

Answer: (A)

The throttle (modulator) circuit is designed to raise or boost the main hydraulic pressure in an automatic transmission as engine load changes. When the throttle is opened, this circuit increases regulator pressure so the clutches and bands receive more force, giving firmer shifts and preventing slip under heavy acceleration. When the throttle closes, pressure drops for smoother, lighter shifts. Lubrication is about oil for bearings and cooling, not for increasing clutch pressure. The governor circuit uses vehicle speed to help time shifts and influence pressure in some designs, but its main role isn’t to boost pressure based on throttle input. The converter-out circuit relates to pressure paths involving the torque converter, not to general pressure boosting for clutch actuation.

The throttle (modulator) circuit is designed to raise or boost the main hydraulic pressure in an automatic transmission as engine load changes. When the throttle is opened, this circuit increases regulator pressure so the clutches and bands receive more force, giving firmer shifts and preventing slip under heavy acceleration. When the throttle closes, pressure drops for smoother, lighter shifts.

Lubrication is about oil for bearings and cooling, not for increasing clutch pressure. The governor circuit uses vehicle speed to help time shifts and influence pressure in some designs, but its main role isn’t to boost pressure based on throttle input. The converter-out circuit relates to pressure paths involving the torque converter, not to general pressure boosting for clutch actuation.