Nissan Frontier D22. Instruction — part 13

OVERALL SYSTEM

AT-21

[RL4R01A]

D

E

F

G

H

I

J

K

L

M

A

B

AT

“D

3

” Position

SAT098J

●

High clutch

●

Forward clutch

●

Forward one-way clutch

Input power is transmitted to front planetary carrier through high clutch. And front plan-
etary carrier is connected to rear internal gear by operation of forward clutch and for-
ward one-way clutch.
This rear internal gear rotation and another input (the rear sun gear) accompany rear
planetary carrier to turn at the same speed.

Overrun clutch
engagement conditions

D

3

: Overdrive control switch “OFF” and throttle opening is less than 3/16

Throttle opening less than 3/16

AT-22

[RL4R01A]

OVERALL SYSTEM

“D

4

” (O/D) Position

SAT099J

●

High clutch

●

Brake band

●

Forward clutch (Does not affect power
transmission)

Input power is transmitted to front carrier through high clutch.
This front carrier turns around the sun gear, which is fixed by brake band, and makes
front internal gear (output) turn faster.

Engine brake

At D

4

position, there is no one-way clutch in the power transmission line and engine

brake can be obtained when decelerating.

OVERALL SYSTEM

AT-23

[RL4R01A]

D

E

F

G

H

I

J

K

L

M

A

B

AT

“R” Position

SAT101J

●

Reverse clutch

●

Low and reverse brake

Front planetary carrier is stationary because of the operation of low and reverse brake.
Input power is transmitted to front sun gear through reverse clutch, which drives front
internal gear in the opposite direction.

Engine brake

As there is no one-way clutch in the power transmission line, engine brake can be
obtained when decelerating.

AT-24

[RL4R01A]

OVERALL SYSTEM

FUNCTION OF CONTROL VALVES

Valve Name

Function

Pressure regulator valve

Optimally controls oil under pressure discharged from oil pump in response to driving
conditions.

Throttle valve

Regulates line pressure to throttle pressure corresponding with throttle opening.

Detent valve

Activates throttle valve via spring in response to changes in throttle opening, thereby
regulating throttle pressure.

Pressure modifier valve

Serves as an auxiliary signal valve of pressure regulator valve to control line pressure
in response to driving conditions.

Accumulator control valve

Regulates accumulator pressure to pressure corresponding with driving conditions.

Instruction valve

Directs line pressure to each oil circuit selected by the selector lever position.

Position

Circuit

1

2

3

4

P

R

N

D

2

1

Hydraulic pressure drains when the shift lever is in N and P.

●

1-2 shift valve

●

2-3 shift valve

●

3-4 shift valve

Provides automatic shift control in response to driving conditions, such as vehicle
speed, throttle opening, etc. Shift control is accomplished by activating or deactivating
the clutch, brakes, brake bands, etc.

2-3 throttle modifier valve

Controls line pressure to provide optimum shifting point (2nd

→ 3rd) during partial-

open throttle.
(2-3 throttle modulator pressure)

3-2 downshift valve

Delivers throttle pressure in a direction that overcomes 2-3 shift valve's governor pres-
sure while shifting from “3rd” to “2nd” in the “D” position.

Kickdown modifier valve

Controls line pressure to provide optimum shifting points (1st

→ 2nd) and (2nd → 3rd)

during kickdowns.
(Kickdown modifier pressure)

4-2 relay valve

Operates in conjunction with the 4-2 sequence valve to prevent downshifting from 4th
to 3rd, then to 2nd while directly shifting from 4th to 2nd.

4-2 sequence valve

Prevents 4th band servo “apply” pressure from draining during direct shifting from 4th
to 2nd before high clutch “apply” pressure and band servo “release” pressure in the
same oil circuit are drained.

3-2 timing valve

Engine speed increases in a short period of time at low engine speeds when accelera-
tor is depressed during downshifts from D

3

to D

2

. However, it takes longer for the

engine to increase speed at high engine speeds. The 3-2 timing valve serves to delay
the band servo “release” draining speed (At this point, the transmission is tentatively
set in Neutral) during downshifts from D

3

to D

2

at speeds greater than those in the

specifications, thereby providing smooth shifting.

1st reducing valve

Controls low & reverse brake “apply” pressure to relief shocks caused by engine
brakes while shifting from 2nd to 1st in the 1 position.

AAT681A