ACURA NSX 1991 Service Repair Manual

Description

Hydraulic Control (cont'd)

Regulator Valve Body

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

relief valve built in. The stator shaft arm contacts the end of the regulator valve.

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

COOLER RELIEF VALVE

REGULATOR VALVE

LOCK-UP CONTROL

VALVE

STATOR SHAFT ARM
REGULATOR VALVE

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Regulator Valve

The regulator valve maintains a constant hydraulic pressure sent from the oil pump to the hydraulic control system, while

also furnishing oil to the lubricating system and torque converter.

Oil flows through B and B'. The oil which enters through B flows through the valve orifice to A pushing the regula* 01

valve to the right. According to the level of hydraulic pressure through B, the position of the valve changes, and the

amount of the oil through B' from D also changes. This operation is continued, maintaining line pressure.

(ENGINE NOT RUNNING) (ENGINE RUNNING)

To TORQUE CONVERTER

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 in 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 arm pushes the regula-

tor spring cap in this direction in proportion to the reaction. The spring compresses and the valve moves to increase

the regulated control pressure or line pressure. Line pressure is maximum when the stator reaction is maximum.
To RELIEF VALVE
From OIL PUMP

STATOR SHAFT

(cont'd)

REGULATOR SPRING CAP
REGULATOR VALVEProCarManuals.com

Description

Hydraulic Control (cont'd)

Main Valve Body

The main valve body is located on the torque converter housing. The oil pump gear, torque converter check valve, manu-

al valve, 1 —2, 2—3, 3—4 shift valves, relief valve and one-way relief valve are all built into the main valve body.

The primary function of this valve body is switching on and off oil passages and controlling the hydraulic pressure going

to the hydraulic control system.

TORQUE COVERTER

CHECK VALVE
OIL PUMP DRIVEN GEAR

OIL PUMP DRIVE GEAR

MANUAL VALVE

DETENT SPRING

MAIN VALVE BODY

2-3 SHIFT VALVE

1-2 SHIFT VALVE
MANUAL VALVE
3-4 SHIFT

VALVE
ONE-WAY RELIEF

VALVE
RELIEF VALVEProCarManuals.com

Oil Pump

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

pump driven gear, and a pump shaft. The oil 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 gears are provided

in the housing. The intake and exhaust lines and the torque converter line are provided in the housing.

One way Relief Valve

The one-way relief valve is used at times of high speed or high temperature to send relief oil to the oil cooler so that

cooling of ATF will be effective.

(cont'd)ProCarManuals.com

Description

Hydraulic Control (cont'd)

Secondary Valve Body

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

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

4-3 kick-down valve built in.

Primarily, it regulates shift valve operation timing and clutch pressure for shock reduction during shifting.

MODULATOR VALVE

4TH EXHAUST VALVE

SERVO CONTROL VALVE

3-2 KICK-DOWN

VALVE

SECONDARY VALVE BODY

4-3 KICK-DOWN VALVE

2ND EXHAUST VALVE
CPC VALVE
2ND ORIFICE

CONTROL VALVE
3RD ORIFICE CONTROL

VALVEProCarManuals.com

Modulator Valve

The modulator valve maintains line pressure from the regulator that is supplied to shift control solenoid valves A/B and

lock-up control solenoid valves A/B, thus maintaining accurate shift and lock-up characteristics.

MODULATOR VALVE

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

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

2nd Exhaust Valve

The 2nd exhaust valve is installed to release 2nd clutch pressure quickly when shifting from the range at which hydraulic

pressure is applied to the 2nd clutch to the position.

2ND ORIFICE CONTROL VALVE

(cont'd)
2ND EXHAUST VALVEProCarManuals.com

Description
Hydraulic Control (cont'd)
Servo Body/2nd Accumulator Body The servo body is mounted on the secondary valve body with the servo valve, 1st accumulator piston, 3rd accumulator
piston and 4th accumulator piston built in. The primary function of the servo body is forward and reverse switching and

control.

The 2nd accumulator body is mounted on the torque converter housing with the 1st-hold accumulator, 2nd accumulator
and limited slip differential relief valve built in.
1ST-HOLD ACCUMULATOR PISTON
2ND ACCUMULATOR PISTON LIMITED SLIP DIFFERENTIAL

RELIEF VALVE

2ND ACCUMULATOR BODY

SERVO VALVE
1ST ACCUMULATOR PISTON
ATF STRAINER

Limited Slip Differential Relief Valve

When the resistance of oil flow inside the limited slip differential becomes large, the limited slip differential relief valve is
opened, and oil is sent to the ATF cooler and cooled. 4TH ACCUMULATOR

PISTON

3RD ACCUMULATOR

PISTON

SERVO BODYProCarManuals.com

Lock-up Valve Body

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

built in.

The capacity of the lock-up clutch is controlled by the lock-up valve body.

LOCK-UP SHIFT VALVE

LOCK-UP VALVE

BODY

LOCK-UP TIMING B VALVEProCarManuals.com

Description

Hydraulic Flow

General of Hydraulic Pressure

Oil Pump
Regulator Valve

Distribution of Hydrualic Pressure

Manual Valve

Throttle Valve B

1-2 Shift Valve

2-3 Shift Valve

3-4 Shift Valve
to select Line Pressure

Throttle B Pressure

Clutch Pressure

Servo Valve

Throttle Valve
Line PressureProCarManuals.com

As the engine turns, the oil pump also starts to operate. Automatic transmission fluid (ATF) is drawn from (99) and

discharged into (1). Then, ATF pressure is controled by the regulator valve and becomes line pressure (1). The torque

converter inlet pressure (92) enters (94) of torque converter through the orifice and discharges into (90).

The torque converter check valve prevents the torque converter pressure from rising.

Under this condition, the hydraulic pressure is not applied to the clutches.

(cont'd)
positionProCarManuals.com