1997 ACURA NSX Service Repair Manual

Hydraulic Control (cont'd)
Description

Regulator Valve Body

The regulator valve body is mounted on the main valve body with the regulator valve, the lock-up control valve and the

cooler relief valve built in. The stator shaft arm contacts the regulator valve spring cap.

The hydraulic pressure (line pressure) is controlled by the regulator valve.ProCarManuals.com

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 the torque converter.

Fluid from the ATF pump flows through B and B'. The regulator valve has a valve orifice. The fluid entering from B flows

through the orifice to the A cavity. This pressure of the A cavity pushes the regulator valve to the right 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. The relief valve and regulator valve move to the left side.

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 D and C also changes. This operation is continued, maintaining line pressure.

Stator Reaction Hydraulic Pressure Control

Hydraulic pressure increases according to torque are performed by the regulator valve using stator torque reaction. The

stator shaft is splined with the stator in the torque converter, and its arm end contacts the regulator spring cap. When the

vehicle is accelerating or climbing (Torque Converter Range), stator torque reaction acts on the stator shaft, and the stator

arm pushes the regulator spring cap in the direction in proportion to the reaction. The stator reaction spring compresses,

and the regulator valve moves to increase the line pressure which is regulated by the regulator valve. Line pressure reaches

its maximum when stator torque reaction reaches its maximum.ProCarManuals.com

Hydraulic Control (cont'd)
Description

Main Valve Body

The main valve body is located on the torque converter housing. The main valve body houses the ATF pump gears, the

torque converter check valve, the manual valve, the 1-2, 2-3, 3-4 shift valves, the relief valve and the one-way relief

valve.

The primary functions of the main valve body are to switch on and off, and to control the hydraulic pressure going to the

hydraulic control system.ProCarManuals.com

ATF Pump

The external tooth gear type ATF pump consists of a housing together with the main valve body, a pump drive gear, a

pump driven gear, and a pump shaft. The ATF pump is installed on the torque converter housing. The pump's driving

force is transmitted by the torque converter pump (directly connected to the engine) to the pump shaft. The intake and

exhaust lines, and the torque converter line are incorporated in the housing.

One-way Relief Valve

The one-way relief valve is used during high speed or high temperature to send fluid to the ATF cooler for ATF cooling.ProCarManuals.com

Secondary Valve Body

The secondary valve body is also mounted on the main valve body with the 3-2 kick-down valve, the CPC valve, the 2nd

orifice control valve, the 3rd orifice control valve, the modulator valve, the 4th exhaust valve, the 2nd exhaust valve, the

servo control valve and the 4-3 kick-down valve built in.

Primarily, it regulates shift valve operation timing and clutch pressure for shock reduction during shifting.
Hydraulic Control (cont'd)
DescriptionProCarManuals.com

Modulator Valve

The modulator valve uses line pressure from the regulator (to shift control solenoid valves A/B) and the lock-up control

solenoid valves A/B, to maintain accurate shift and lock-up characteristics.

2nd Orifice Control Valve

For smooth shifting between the 2nd and 3rd gear, the open pressure on the 2nd gear side is relieved through a fixed ori-

fice. The valve also moves to equalize pressure differences between the 2nd and 3rd gear.

2nd Exhaust Valve

The 2nd exhaust valve releases 2nd clutch pressure quickly when shifting from the range where hydraulic pressure is

applied to the 2nd clutch in the position.ProCarManuals.com

Hydraulic Control (cont'd)
Description

Servo Body

The servo body is mounted on the secondary valve body with the servo valve, the 1st accumulator piston, the 3rd accu-

mulator piston, and the 4th accumulator piston built in to it. The primary functions of the servo body are to switch the

direction foward and reverse, and to control hydraulic pressure reduction for shifting shock.

2nd Accumulator Body

The 2nd accumulator body is mounted on the torque converter housing with the 1st-hold accumulator, the 2nd accumula-

tor and the limited slip differential relief valve built in to it.

Limited Slip Differential Relief Valve

When the resistance of fluid flow inside the limited slip differential is high, the limited slip differential relief valve is

opened, and fluid flows to the ATF cooler.ProCarManuals.com

Lock-up Valve Body

The lock-up valve body is mounted on the regulator valve body with the lock-up shift valve and the lock-up timing B valve

built in.

The capacity of the lock-up clutch is controlled by the lock-up shift valve and the lock-up timing B valve.ProCarManuals.com