1977 DATSUN PICK-UP low oil pressure

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

Automatic
Transmission

R
RANGE
REVERSE

R

In
R

range
the

front
dutch
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

Slationary
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

f

When
Ihe
manual
valve

CV
is

posi

tioned
at
R

range
Ihe
oil

having
Ihe

line

pressure
7
is

directed
to

line

pressure
circuits
5
and

6
The

pressure
in

the
circuit
5
actuates
the

low
and
reverse
brake
after

being

introduced
into
line

pressure
circuit

12

through
the
I
st

2nd
shift
valve

@
The

pressure
in
Ihe

circuit

op

erates
the
release
side
of
the
band

servo
and

the
front
clutch
after

being

led
to

line

pressure
circuit

10

through
the
2nd
3rd
shift
valve

@

The
throtlle

pressure
16
and
the
line

pressure
6

which

vary
with
the

degree
of
acceJerator

pedal
depression

both
act

on
the

prcssure
regulator

valve

CD
and

press

against
its
valve

CD

increasing
line

pressure
7
In
R

range
the

governor

pressure
is
absent

making
all
slldl

valves
as
the
J
SI

2nd

shift
valve

@
2nd
3rd
shift
valvc

@
and

pressure
modifier
valve

j

inoperative
C

Fig
AT

26
Power

transmi
ion

during
R

range

A
TOS5

Fig
AT
27

Operation
attach
mechanism

during
R

range

G
Clutch
Low
A

Band
servo
One

Parkin

Ran
no
wa

plwl
ratio

Front
Rear

brake

Operllioo
Rdr
ue

clutch

k
on
on

Revctte
1
181
on
on
on

Neutnl

DI
Low
1
418
on
on

Driw
D2
Second
1
458
on
on

DJ

Top
1
000
on
on
on
on

2
Second
1
458
on
on

12
Second
1
458
on
on

I

II
Low
2
458
on
on

AT
16

R

range
Reverse
Automatic
Transmission

TOl
QuaConverter

o

IIi
0

ou

14

Q

FI
Lu

IUt
O

Front

Lub
lc

O
lnV
ly

R
MO
V
l
Front

Clutdt
LowaoA

B
k

e
k

B

Clutch

ID
VK

n

V
lv
@
ftV
1

I

j

Throttle

O
in

V
Otlflce

Check

V
III

@lnd
3rdShih

V

zz

@
2nd
rd
TIm

If

V
Iy

Second
Lock
V

3
I

Zl

Not

M
k
d
X
er
0
1

LI
p
O
nOf
f

P

G
preau

I
J

Torqu
0
0
pr

Throttl

p
1
s
co

O
V
0

O
V

Fig
A
T
28

AT
17
Oil

pressure
circuit

diagram
n
II

range
Reverse

N
RANGE
NEUTRAL
Automatic
Transmission

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

CD
to
maintain

the
line

pressure
7
and
the
oil
is
led

to
the
manual
valve

V
vacuum
throt

tle
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
regulator
valve

CD
G
Clutch
Low

Band
servo
One

Pukiq

R
w

pawl
ntlo

Front
Rur

br
ke
Optruion
Release

clutch

PIlIi
on
on

Reverse
2
182
on
on
on

Neut
1

01
Low
2
458
on
on

Drive
02
Second
t
458
on
on

03

Top
1
000
on
on
on
on

2
Setond
1
458
on
on

12
Second
1
4
58
on
on

1

II
Low
2
458
on
on

AT

18