1977 DATSUN PICK-UP oil pressure

The
control
valve

assembly
consists

of

the

following
valves
See

Figure

AT

20

I
Pressure

regulator
valve

PRV

2

Manual
valve

MNV

3
I

st
2nd

shift
valve

FSV

4

2nd
3rd

shift
valve

SSV

5

Pressure
modifier
valve

PMV

6
Vacuum
throttle
valve

VTV

7

Throttle
back

up
valve

TBV

8
Solenoid
downshift
valve
SDV

9

Second
lock
valve
SL
V

10
2nd
3rd

timing
valve

TMV

Pressure

regulator
valve

PRV

The

pressure
regulator
valve
re

ceives
valve

spring
force
force
from

the

plug
created

by
the
throttle

pres

sure
16
and
line

pressure
7

and

force
of
the
throttle

pressure

18

With
the
interaction

of
those
forces

the
PRY

regulates
the

line

pressure
7

to
that

most
suitable
for
individual

driving
conditions

The
oil
from
the
oil

pump
is

ap

plied
to

the

ring

shaped
area

through

orifice
20
As

a
result
the
PRV
is

depressed
downward
and
moves
from

port
7

up
to
such
extent
that
the

space
to
the
next
drain

port
marked

with
X
in

Figure
AT
10

opens

slightly
Thus
the

line

pressure
7
is

balanced
with
the

spring
force
there

by
balancing
the
PRV
In
this

opera

tion
Ihe

space
from

port
7
to
the

subsequent
converter
oil

pressure
14

circuit
has
also
been

opened
As
a

result
the
converter
is
filled

with

pressurized
oil
in
circuit
14
and
this

oil
is
further
used
for
lubrication
of

the
rear
unit
Moreover

part
of
the
oil

is
branched
and
used
for
lubrication

of

the
front
unit
for
the
front
and
rear

clutches

When
Ihe
accelerator

pedal
is
de

presscd
the
throttle

pressure
16
in

creases
as
described
in
the

preceding

paragraph
oil

pressure
is

applied
to

the

plug
through
orifice
21

and
this

pressure
is

added
to
the

spring
force

As

a
result
the
PRV
is

contrarily

forced

upward
space
to

the
drain

port

is
reduced
and
Ihe

line

pressure
7

increases
Automatic

Transmission

11

AT095

Fig
AT
10
Pressure

regulator
ualue

When

the

range
is
selected
at
R

Reverse

the
line

pressure
6
is

applied
10

the

plug
in
a
manner
identi

caito
the

throttle

pressure
16
and

is

added
10
the

spring
force

Consequent

ly
the
line

pressure
7

further
in

creases

When
vehicle

speed
increases

and

the

governor
pressure
rises
the

theot

tle

pressure
18
is

applied
to
the

port

on
the

top
of
the
PRV

and

pressure
is

applied
contrarily
against
the

spring

force
As
a

result
the
line

pressure
7

decreases
Moreover
at
individual

con

ditions
the
line

pressure
7

is

equal
to
the
line

pressure
6

and
the
throttle

pressure
16
is

equal
to
18

Manual
valve
MNV

The
manual
lever

turning
motion
is

converted
to

reciprocating
motion

of

the
manual
valve

through
a

pin
and

the
MNV
is

positioned
so
that
the
line

pressure
7
is
distributed
to
the

indi

vidual
line

pressure
circuits
at
each

P

R
N

D
2
or
I

range

as

shown
below

P

range

7
4
SDV
and
TBV

5

FSV
12
TBV
and

Low

reverse
brake

R

range

7
4

same
as
above

5

same
as
above

6

PRY
and

SSV
F
C

and
band
release

N

range

D

range

7
7

None

I

Governor
valve

FSV

and
rear
clutch

2

SLY

3

SL
V

and
SSV

2

range

7
I
Same
as
above

2

SL
V
9
Band

applied

4
SDV
and
TBV

I

range

7
I
Same
as
above

4
Same

as
above

5

FSV

Moreover
1

2
3
4
5

and

6

are

always
drained
at
a

position

where
the
line

pressure
is

not
dis

tributed
from
7

u
JJX
g4Vhl

dIillillt
1
dlMIi
W
ld

IiIb
It
i
B
J

jd
l
tJj
fitMi
td

j
L@

x
x

j
j

P
R
N

17
l

AT7
AT096

Fig
AT
11

Manual
ualvp

1st

2nd
shift

valve
FSV

The

FSV
is
a

transfer
valve
which

shifts

gears
from

low
to

second
When

Ihe
vehicle
is

stopped
the

FSV
is

depressed
to

the

right
side

by
force
of

a

spring
located
on
the

left
side

putting
the

FSV
is
in
the

low

position

When
vehicle

speed
increases
the

governor

pressure
15
is

applied
to

Ihe

right
side
of

the
FSV
and
the
FSV

is
forced

toward
the
left

Contrarily

the
line

pressure
I

togelher
with
the

spring
force
force

the
FSV

toward
the

right

opposing
the

governor

pressure

15

When
the

vehide

speed
exceeds
a

certain
level

the

governor
pressure

15
exceeds
the
sum
of
the

throttle

pressure
and
Ihe

spring
force
and
the

FSV
is

forced
toward
the
left

When
the
FSV
is

depressed
10
a

certain

position
the

lire
pressure
I

is

closed
and

only
the

spring

depresses

the

FSV
toward
the

right
and
it
is

depressed
to

the
end
for

a
moment
As

a

resull
the

line

p
ressure

lJ
is
for

warded

to
8
the
band

servo
is

engaged

through
the
SLY

and
the

speed
is
shifted
to
2nd

With
the

accelerator

pedal

depressed
the
FSV

remains
iIi

the
Low

position
unless

the

governor
pressure
IS
increases

to

a

high
leVel

corresponding
to
the
line

pressure
I
since

the

line
pressure

I

increase
when
the
accelerator

pedal
is

depresse9

Contrarily
when

vehicle

speed
de

creases

the

governor

pressure
15

decrease
Howeve
f

the

gear
is
not

shifted
to

Low

nless
the

governor

pressure
15
becomes

zero
since

the

force

depressing
the
FSV
toward
the

right
is

being
delivered

only
by
the

spring

Low
in

range
I
is
led
to

the

low
and
reverse

clutch
from
line

pres

sure
5

through
line

prbssure
12

2nd
is
simultaneousi

y
led
to

the
ieft

end

spring
unit

Consequently
al

thougp
the

goverflor
pressure
in

creases

the
valve
is
still
forced
toward

the

right
and
the
SFV
is

fixedjn
the

Low

position
When
kicked
down
to

the
2nd

speed
the
SDV

operates

and

the
line

pressure
13
forces
the

FSV

toward
the

right
Although
the
Automatic
Transmission

governor
pressure
15
is

considerably

high
the
valve
is

forced

completely

toward

the

right
and
the

FSV
is

returned
to
the

Low

position
This

operation
is

alled

Kickdown
shift

15

j

13

1

c5

I

0

t

r

I

I

q
1

AT091

Fig
AT
12

lsl
2nd

shift
valve

2nd
3rd

shift
valve
SSV

The

SSV
is

a
transfer
valve

which

shifts

gears
from

2nd
to

3rd

When
the
vehicle
is

stopped
the
SSV

is

forced
toward

the

right
by
the

spring
and
is
in
the

2nd

position
It

is

so

design
d
however

that
the
FSV

can

decide
to
shift

either
to

Low
or

2nd

When

the
vehicle

is

running
the

governor
pressure
15
is

applied
to

the
right
end
surface

and
th
SSV
is

forced

toward
the
left

Contrarily
the

Spri
l
force

line

pressure
3

and

throttle

press
re
19
force
the

SSV

toward
the

right

When
vehicle

speed
exceeds
a
cee

tain

level
the

governor

pressure
sur

passes
the
sum
of
the

spring
force
line

pressure
and
throttle

pressure
and
the

valve
is
forced
toward

the
left
The

line

pressure
3
is

then
closed
Con

sequently
the
forces

being
rapjdly

unbalanced
the
force

depressing
the

SSV
toward
the

right
decreases
and

thus
the
SSV
is

depressed
to

the
l

ft

end
for
a
moment

With
Ihe

SSV

depressed
toward
the

left
end
lhe

line

pressure
3

is
connected
with

the
line

pressure
10

the
band
servo
is
re

leased
the
front

clutch
is

engaged
and

AT
8
speed
is
shifted
to

3rd

When
the

accelerator

pedJI
is

de

prcssed
both
the

line

pressure
3
and

the

throttle

pressure
19

are

high
allll

the

SSV
is
thus

retained
in
nd

unless
the

governor

pressure
15

ex

ceeds
the

line

pressure
3
and

the

throttle

pressure
19

In
the

3rd

position
force

de

pressing
ihe
SSV

toward
the

right
is

retained

only

by
the

throttle

pressure

16
and

the
throttle

pressure
16

is

slightly
Idwer

than
that
toward
the

right
which
is

applied
while

shifting

from
2nd
to

3rd

Consequently
the

SSV
is
returned

to
the

2nd

position
at
a

slightly

lower

speed

Shifting
from
3rd
to

2nd

occurs
at
a

speed
slightly
lower

than
that

for
2nd
to
3rd

shifting

When
kicked
down
at
3rd

line

pressure
13
is

led
from
the
SDV
and

the

SSV
is
forced

toward
the

right

Although
the

governor
pres
ure
is

con

siderably
high
the
valve
is
forced

completely
loward
the

right
and
tht

SSV
is

thus
returned
to
2nd

posi

tion

fhis

operation
is
called
K
cli

down
shift

When

the
shift
iever
is

shifted
to

2

or
I

range
at
the
3rd

speed

the
line

pressure
3
if
diained

at
the

MNV

Consequently
the

front
clutch

and
band
servo

releasing
oils

are

drained
As
a
result

the
transmission
is

shifted
to
2nd
or
low

speed
ai

though
the

SSV
is
in

the
3rd

posi

tion

When
the

specd
IS

shifted
io

the

3r
1
a
one

way
orifice
24

on
the

topof
the
SSV
relieves
oil

transmitting

velocity
from
the
line

pressure
3
to

the
line

pressure
10
and
reduces

the

shock

generated
fioni

the

shifting

Contrarily
when
the
lever
is
shifted

to
2
or
I

range
and
the

speed
is

shifted
from
3rd
to
the
2nd
the

orifice

checking
valve

spring
24
is

depressed
the
throttle

becomes
in

effective

the
line

pressure

10
is

drained

quickly
and

delay
in

shifting

speeds
is

thus
eliminated

The
throttle
of
line

pressure
6

transmits
Hie

oil

transmitting

velocity

from
line

pressure
6
to
line

pressurc

10
wtien
the

lever
is
shifted
to
the

R

range
and
transmits
drain
veloci

ty
from
line

pressure
10
to
line

3

Jit
f
ng
valve

24

1

3

L
l

r

I
Js

I
i

ilr
t
pressure
6
when

shif
ing
from
3rd

to
2nd
at
D

range
Thus
the

throttle
of
line

pressure
6
reduces

the

shock

generated

fro
shifting

A

plug
in
the

SSV
left

end

readjust

the

throttle

piessu
e
I
6
which
varies

depending
on
the

engine
throttle
con

dition
to
a
throttle
pressure
19

suiled
to
the

sp
ed

change
control

Moreover
the

plug
is
a
valve
which

applies
line

P

esspre
13
in
lieu
of
the

throttle

pressure
to
the
SSV
and
the

FSV
when
kickdowri
is

performed

When
the
throttle

pressure
16
is

applied
to
the

left
side
of
this

plug

and
the

plug
is

epressed
toward
the

right
a

slight

space
is
formed
from
the

throttle

pressure
6
10

19
A

throt

tIepressu
19

w
1iFh
is
lower

by
the

pressure
loss

equivalent
to
this

space
is

rH

1

Pressure
Odifier
valve
PMV

I

Compared
to
the

operating

pressure

required
in

starting
th
vehicle
the

ppwer
trimsinitting
capacity
of
the

clutch
that
is

required
operating

pres

sure

may
be

lower
when
the
vehicle
is

once
started
When
the
line

pressure
is

retained
at

a

high
level

up
to

a

high

vehicle

speed
shock

gerieraled
from

the

shirring
increases
arid
the

oil

pump
loss
also
jncrdases
In
order
to

prevent
his
the
t

lrott
le

pressure
must

be
l

hanged
over

with
the

operation
of

the

governor
pressure
15
to
reduce

Ihe
line

pressure
The
PMV
is
used
for

this

purposc
Automatic

Transmission

generated
the

piessure
loss
is
adde
d
to

the

spring
force

and
the

plug
is
lhus

forced

back
from
the

right
to
the

left

When
this

pressure
19
increases
ex

cessively
the

plug
is
further

depressed

toward
the

left

space
from
the
lhrot

tle

pressure
19
to

the
drain
circuit

13

increases
and
the
throttle

press

ure

19
decreases
Thus
the

plug
is

balanced
imd
the
throttle

pressure

19
is

reduced
to
Ii
certain
value

against
the
throttle

pressure
6

Wheri

performing
kickdowri

the

SDV
moves
a

high
line

pressure
is

led

to
the
circuit

19
from
the
line

pressure
circuit

13
which
had

been

drained

the

plug
is
forced
toward
the

left

and
circuit

19
becomes

equal
to

the
line

pressure
13

I

W
15

I

A
TOgS

Fig
iT
13
2nd
3rd

shift
vallJe

I

When

the

governor
pressuie
IS

which
is

applied
to
the

right
side
of

the
PMV
is
low
the
valve
is
forced

toward

the

right
by
the
throttle

ines

sure
16

applied
to
the
area
differ

ence
of
the
value
and
the

spring
foice

and
t

he
circuit

from
circuit

16
to

circuit
18
is
closed
However
when

vehicle

speed
increases
andl
the

gaver

nor

pressure
15
exceeds
a
certain

level
the

governor
pressure
toward

the

left
which
is

applied
to
the

right
side

exceeds
the

spring
force
and
the

throt

tle

pressure
16

toward
thc

right
the

valve
is

depressed
loward
the
lefi

and

the
throttle

pressure
is
led
from
circuit

AT

9
16
to
circuit

18
This
throttle

pressure
18
is

applied
to
the

top
of

the
PRV
and
the
force
of
the

line

pressure
source
7
is
reduced

Contra

rily
when

the
vehicle

speed
decreases

arid
the

governor

ipressure
15
de

creases
the

force
toward
the

fight

exceeds
ithe

governor
pressure
the

valve
is

forced
back
toward
the

right

and
the

throttle

pressure
18
is

drained
to
the

spring
unit

This
valve
is

sWitched
when
the

throttle

pressure
and
the

governor

pressure
are

high
or
when

tIiey
are

both
Tow
i

i
I
11

18
16

n

r

I

I

15

AT099

Fig
AT
14

Pre
ure

modifier
valve

Vacuum
thro
le
valve
VTV

The

vacuum
t
rottle
valve
is
a

regula
tor
valve

whiCh
uses
the
line

pressure
7

for
the

pressure
source

and

regulates
the

throttle

pressure
16

I

which
is

proportioned
t
the

force
of

the

vacuum

diaphragm
The
vacuum

dia

phragm
yories
depending
on
the

engine
throt
le

condition

negative

pressure
in
the

inta
e
line

When
the
line

pressure
7
is

ap

plied
to
the
bottom

through
the

valve

hole
and
the
v

a
ve
is

forced

upward

space
from
the
line

pressure
7
to
the

throttle

pressure
16
is
dosed
and

the

space
from
the
Ihrottle

pressure

16
to

the
drain
circuit
17
is
about

to

open
In

this

operation
the
throttle

pressure
16
becomes
lower
than

the

linep
s

ureY
btthe
p
e
sur

9
iv

alenl
of
the

loss
of

space
and
Ihe

force

depressing
tlie
rod
if
the

vaeuum

diaphragm
is

balanced
wit

Ii
thethrot

tie

pressure
16
a

pplied
upward
tOlthe

bottom

When
the

erigine

torque
is

high
Ihe

negative
pressure
in
the
intake
iirie

rises

tending
ioward

atmospheric

pressure
and
the
force
of
the
rod
to

depress
the
valve
increases
As
a
result

the
valve
is

depressed
downward
the

2nd
3rd
timln
valve
TMV

This
valve
is
a
transfer

valve
which

switches
the

by

pass
circuit
of
the

orifice
22
in
the
front
clutch

pres

sure
circuit

II
in

response
to
vehicle

speed
and
throttle
condition
A
force

created
when
the

governor
pressure

IS
is

applied
to

the
bottom
of

the

TMV

constitutes
the

upward
force

and

a
force

created
when
the

spring

force
and
the
throttle

pressure
are

applied
to
the

top
of
the
TMV
consti

tutes
the
downward

force

When
the
throttle

pressure
16
is

lower
than
the

governor

pressure
IS
Automatic
Transmission

the

upward
force
exceeds
the
down

ward
force
the

valve
is
locked

upward

and

passage
from

circuit
l0
2nd

from
the

Top
to

circuit
II

is

closed

Consequently
the
line

pressure

10
is

led
to

the
front
clutch

circuit

II

through
the
orifice
22

and
the

oil

pressure
is
thus

transmitted

slowly

However
under
normal

shifting
the

throttle

pressure
16
has
a

pressure

exceeding
a
certain

level
and
the

downward
force
e
xceeds
the

upward

force
As

a
result
the
valve
is

locked

downward
the

passage
from

circuit

10
to
circuit

II
is

opened
and
the

orifice
22
is

bypassed

ATll
AT104

Fig
JlT
19
2nd
3rd

timing
valve

HYDRAULIC
SYSTEM

AND

MECHANICAL

OPERATION

The

operating
system
of
oil

pres

sure
in

each

range
is

described
below

The
oil

pressure
in
each
circuit

shown
in

the
illustration
is
classified
as

follows

according
to
the

function

fhe
numeraJs
show

the
circuit

num

bers

Pressure
source
of
the
line
7

Operating
Iinc

prcssure

for
friction
elements

123456
8910
1112

Auxiliary
line

pressurc
13

Throttle

system
pressure

16
17
18

19

Others
14
15

Oil

pump
discharge
hole
7

Cd

Torque
converter

pressure
14

Rear
iutch

prc
surc
1

FTOOI
c1
tL
h

prc
ur

It

J
1
011
pump
Sllctlon
hole

M

IIJ1iIII
Automatic
Transmission

Fig
AT
21

Identification
of
oil
channels

in
oil

pump
AT105
Oil

pump
suction
hole

ATl06

Fig
AT

22

Identification
of
oil
channels
in
case

front
face

I
o

Oil

pump
dischar
hole
7

I9JM

c

Torque
converter

f
Os
I
1L

0
ervo
Ie
ease

pressure
14

0
pressure
10

Rear
clutch

Servo
t

ightening

ho
L

pressure
l
0
1

pressure
9
lJ
L

I
c

I

Front
clutch
IT

0

LIO
reverse
brake

pressure
12

U

r
FT

II
pressure
11

rrOil
pump
suction
hol

J

C
Jf
JC
O
Governor

pressure
15

Governor

feed

pressure
l

An07

Fig
AT
23

Identification
of
oil
channels

in
case

face

AT
13

Automatic
Transmission

P

RANGE
PARK

The

operation
of
clutches
and

band

are
functionally
the
same
as
in

Neu

tral

In

parking
however
when
the

parking
pawl
meshes
in

a

gear
which
is

splined
to

the

output
shaft
the

output

shaft
is

mechanically
locked
from

rotating
Free
Lock

AT086

Fig
AT

24

Parlling
mechanum

The
oil

discharged
from
the
oil

Low
Band
ervo
On

pump
is

fed
to
each

part
in
a

similar
Gw
Clutch

Parkin

Range

atia
Il

Yer5e

r

pawl

manner
to
that
of
the
N

range
The
Fron
Rear
brakt

Operation
Release
clutch

oil

having
the
line

pressure
7
which

Park
on

has
been
introduced
into

the
manual

valve

Il
reaches
the
I

st
2nd
shift
Re
er
2
132
on
on
on

valve

CID
through
the
line

pressure

circuit

5
As
the
1st
2nd
shift
Neutral

valve
s
force
to
th

right
hand
ide
PI
L
w
2
3
on

by
the

spring
the
line

pressure
5
and

Drive
P2
Second
14S3
on
on

12
actuates
the
low
and
reverse

brake

through
the
groove
Also
Ihe
03

Top
1
000
on
on

parking
pawl
engages
with
the
outer

2
Second
1
458

teeth
of
the
oil
distributor

by
means

of
the

manual
lever
mechanically
12
Second
1458
on
on

locking
the

output
shaft

II
Low
2
453
on

AT
14

R
RANGE
REVERSE

In
R

range
the

front
clutch
and

the
low
and
reverse
brake
are

applied

The

power
flow
is

through
the

input

shaft
front
clutch
and

connecting

shell
to
the

sun

gear
Clockwise
rota

tion
of
the
sun

gear
causes
counter

clockwise
rotation
of
the

rear

planeta

ry
gears
With
the

connecting
drum

held

stationary
by
the
low
and

reverse

brake
the
rear

planetary
gears
rotate

the
rear
internal

gear
and
drive
the

flange
counterclockwise
The

rear

drive

flange
splined
to
the

output
shaft

rotates
the

output
shaft
counterclock

wise
at
a

reduced

speed
with
an

increase
in

torque
for
reverse

gear
Automatic
Transmission

R

Fig
AT

26
Power

tranamis
ion

during
R

range

m
i

1

A
TOBS

Fig
A
T
21

Optrationof
each
mechanism

during
R

range

When
the
manual
valve

V
is

posi

Clutch
Low

Band
servo
One

tioned
at

R

range
the
oil

having
the
Gear

Partina

Ranae
re
ne

way

line

pressure
7
is

directed
to
line
ralio

Front
Rear

brake
Openlion
Relulie

clutch
plwl

pressure
circuits
5

and
6
The

pressure
in
the
circuit
5
actuates
the
Park
on
on

low
and
reverse

brake
after

being
Ruene
2
182
on
on
on

introduced

into
line

pressure
circuit

Neutral

12

through
the
I

st
2nd
shift
valve

ID
The

pressure
in

the
circuit

op
DI
Low
2
458
on
on

erates
the
release
side
of
the
band

servo
and
the
front
c1u
tch
after

being
Driowe
D2
Second
1
458
on
on

led
to
line

pressure
circuit
0
D3

Top
1
000
on
on
on

through
the
2nd
3rd
shift
valve

@

2
Second
1
458

The
throttle

pressure
I
6
and
the
line
on
on

pressure
6
which

vary
with
the

12
Second
S8
on
on

degree
of
accelerator

pedal
depression

II
Low
2
458

both
act
the

pressure
regulator
on

on

on

valve

CD
and

press

against
its
valve

CD

increasing
line

pressure
7
In
Rn

range
the

governor

pressure
is
absent

making
all

such
valves
as
the
1st
2nd

shift
valve

ID
lnd
3rd
shift

valvc

@
and

pressurc
modifier
valve

inoperative

AT16

N
RANGE

NEUTRAL

In

N

range
none
of

the
clutches

and
band
are

applied
thus
no

power
is

transmitted
to

the

output
shaft

The

pressure
of
oil

discharged
from

the
oil

pump
is

regulated
by
the

pressure
regulator
valve

Dto
maintain

the
line

pressure
7

and
the
oil
is

led

to
the
manual
valve

@
vacuum
throt

tie
valve

@
and
solenoid
down
shift

valve

@
The
oil
is
further
introduced

into

the

torque
converter
at
its

op

erating

pressure
14
and
a

portion
of

this
oil

is
distributed
to
each

part
as

the
front
lubricant
The
oil
which
has

been

discharged
from
the

torque
con

verter
is

also
distributed
to
eacn

part

as
the

rear
lubricant

As
the
oil

pump
rotates
at
the
same

speed
as
the

engine
the
oil

pump

discharge
increases
with

engine

speed

But
the

surplus
oil
is
returned
to
the

oil

pan
by
the

pressure
regula
tor
valve

D
Automatic
Transmission

Geu
Clutch
Low
4

Band
crvo
One

Pultin

R

atio
WI

pawl

Front
Rear

brake
Operation
Release

clutch

Park
on
on

Reverse
2
182
on
on
on

Neutral

Dt
Low
2
458
on

on

Drive
D2
Second
1
458
on
on

m

Top
1
000
on
on

on
on

2
Second
1
458
on

on

12
Sec
ond
1
458
on
on

II
Low
2
458
on
on

AT
la