rims DATSUN PICK-UP 1977 Service Manual

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