Hydraulic Control

GENERAL
The hydraulic control system is controlled by the ATF pump, valves and accumulators in the valve bodies. The ATF pump is driven by splines on the end of the torque converter which is attached to the engine. Fluid from the ATF pump flows through the regulator valve to maintain specified pressure through the main valve body to the manual valve, direction pressure to each of the clutch. The valve body includes the main valve body, the regulator valve body, the lock-up valve body, the secondary valve body, the servo body, the modulator valve body and the governor body. The lock-up control solenoid valve A/B assembly is bolted on the outside of the torque converter housing.





MAIN VALVE BODY
The manual valve, the 1-2 shift valve, the 2-3 shift valve, the 3-4 shift valve, the 4th exhaust valve, the 3-2 timing valve, and the relief valve are all assembled in the main valve body. The primary functions of the main valve body are to switch fluid passage on and off and to control the hydraulic pressure going to the hydraulic control system.





SECONDARY VALVE BODY
The secondary valve body is located on the main valve body. The 2nd ON orifice control valve, the 4-3 kick-down valve, the 2-3 orifice control valve, the governor cut valve, the 2-1 timing valve, the reverse control valve, the servo control valve, and the clutch pressure control (CPC) valve are assembled in the secondary valve body.

SERVO BODY
The servo body is located on the secondary valve body. The servo valve, which is integrated with the shift fork shaft, the throttle valve A and B, the 2/3-4 orifice control valve, and the accumulator pistons are all assembled in the servo body.





MODULATOR VALVE BODY
The modulator valve body with the modulator valve is located on the servo body.






REGULATOR VALVE BODY
The regulator valve body is located on the main valve body. The regulator valve body consists of the regulator valve, the torque converter check valve, the cooler check valve, and the lock-up control valve.





REGULATOR VALVE
The regulator valve maintains a constant hydraulic pressure from the ATF pump to the hydraulic control system, while also furnishing fluid to the lubricating system and torque converter. Fluid flows through B and B'. The fluid which enters through B flows through the valve orifice to A, pushing the regulator valve to the right. According to the level of hydraulic pressure through B. the position of the valve changes, and the amount of the fluid through B' from D thus changes. This operation is continued, thus maintaining the line pressure.

NOTE: When used, "left" or "right" indicates direction on the illustration.





STATOR REACTION HYDRAULIC PRESSURE CONTROL
Hydraulic pressure increase, according to torque, is performed by the regulator valve using stator torque reaction. The stator shaft is splined to the stator and its arm end contacts the regulator spring cap. When the car is accelerating or climbing (Torque Converter Range), stator torque reaction acts on the stator shaft and the stator shaft arm pushes the regulator spring cap in this direction of the arrow in proportion to the reaction. The spring compresses and the regulator valve moves to increase the regulated control pressure or line pressure. Line pressure is maximum when the stator reaction is maximum.





LOCK-UP VALVE BODY
The lock-up valve body contains the lock-up shift valve and the lock-up timing B valve, and it is located on the regulator valve body.





ACCUMULATOR PISTONS
The accumulator pistons are built into the servo body and the right side cover. The 1st-hold accumulator piston is in the right side cover, and the 1st, 2nd, 3rd, and 4th accumulator pistons are in the servo body.