A/T System Description - Hydraulic Controls

A/T System Description - Hydraulic Controls

Hydraulic Controls

The valve body includes the main valve body, the regulator valve body, the secondary valve body, and the accumulator body. The ATF pump is driven by splines on the end of the torque converter which is attached to the engine. Fluid flows through the regulator valve to maintain specified pressure through the main valve body to the manual valve, directing pressure to each of the clutches. Shift solenoid valves A, B, C, and D are mounted on the accumulator body. A/T clutch pressure control solenoid valves A, B, and C are mounted on the transmission housing.






Hydraulic Controls (cont'd)

Main Valve Body

The main valve body contains the manual valve, the modulator valve, the torque converter check valve, shift valves A, B, and E, CPC valve A, the servo control valve, the relief valve, the lock-up shift valve, the lock-up timing valve, the lubrication control valve, the lubrication check valve, the ATF pump drive gear, and the ATF pump driven gear. The primary function of the main valve body is to switch hydraulic pressure on and off to control the hydraulic control system.






Regulator Valve Body

The regulator valve body is located on the main valve body. The regulator valve body contains the regulator valve, the cooler check valve, the lock-up control valve, the servo valve/shift fork shaft, and the 3rd accumulator.






Regulator Valve

The regulator valve maintains constant hydraulic pressure from the ATF pump to the hydraulic control system, while also providing fluid to the lubrication system and the torque converter. Fluid from the ATF pump flows through B and B'. Fluid entering from B flows through the valve orifice to the A cavity. This pressure of the A cavity pushes the regulator valve to the spring side, and this movement of the regulator valve uncovers the fluid port to the torque converter and the relief valve. The fluid flows out to the torque converter and the relief valve, and the regulator valve returns under spring force. According to the level of the hydraulic pressure through B, the position of the regulator valve changes, and the amount of fluid from B' through the torque converter changes. This operation is continued, maintaining the line pressure.





Increases in hydraulic pressure according to torque are regulated by the regulator valve using stator torque reaction. The stator shaft is splined to the stator in the torque converter, and the stator shaft arm end contacts the regulator spring cap. When the vehicle is accelerating or climbing (torque converter range), stator torque reaction occurs on the stator shaft, and the stator shaft arm pushes the regulator spring cap in the direction of the arrow in proportion to the reaction. The stator reaction spring compresses, and causes the regulator valve to increase the line pressure which is regulated by the regulator valve. The line pressure reaches its maximum pressure when the stator torque reaction reaches its maximum travel.






Hydraulic Controls (cont'd)

Secondary Valve Body

The secondary valve body is on the main valve body. The secondary valve body contains shift valves C and D, CPC valves B and C, the reverse control valve, and the reverse CPC valve.






Accumulator Body and Regulator Valve Body

The accumulator body is on the secondary valve body, and contains the 1st, 1st-hold, 2nd, 4th, 5th accumulators, and shift solenoid valves A, B, C, and D. The 3rd accumulator is in the regulator valve body.