cruise control DATSUN 210 1979 Service Manual

Automatic
Transmission

HYDRAULIC
CONTROL
UNIT
AND

VALVES

The

hydraulic
or
a
tomatic
control

system
is

comprised
of
four
4
basic

groups
the

pressure
supply
system

the

pressure
regulating
system
the

flow
control
valves
and
the
friction

elements

PRESSURE
SUPPLY
SYSTEM

The

pressure
supply
system
consists

of

a

gear

type
oil

pwnp
driven

by
the

engine
through
the

torque
converter

The

pump
provides

pressure
for
aU

hydraulic
and
lubrication
needs

PRESSURE
REGULATOR

VALVES

The

pressure
regulating
valves
con

trol
the

output
pressure
of
the
oil

pump

Pre
ure

rellulator
valve

The

pressure
regulator
valve
con

trois
mainline

pressure
based
on

throttle

opening
for
the

operation
of

the
band
clutches
and

brake

Governor

valve

The

governor
valve
transmits

re

gulated
pressure
based
on
car

peed

to
the

shift
valves
to
control

upshifts

and
downshifts

Vacuum
throttle
valve

The
vacuum

throttle
valve
transmits

regulated
pressure
based
on

engine

load
vacuum
This

pressure
controls

the

pressure
regulator
valve

Also
this

pressure
is

applied
to
one
end
of
the

shift
valves
in

opposition
to

governor

pressure
which
acts

on
the
other

end

of
the
shift
valves

controlling

upshift

and
downshift

speeds
FLOW
CONTROL
VALVES

Manual
valve

The
manual
valve
is
moved

manual

Iy
by
the
car

operator
to
select
the

different
drive

ranges

1
2
ShHt
valve

The
1
2

shift
valve

automaticaIly

shifts
the
transmission
from
first

to

second
or
from
second
to
first

depend

ing

upon
governor
and
throttle

pres

sure

along
with

accelerator

position

solenoid
downshift
valve
See

Hy

draulic
Control
Circuits
Drive

2

2
3
ShHt
valve

The
2
3
shift
valve

automaticaIly

shifts
the
transmission
from
second
to

top
gear
or
from

top
to
second
de

pending

upon
governor
and
throttle

pressure
or
accelerator

position
sole

noid
downshift
valve

See
Hydraulic

Control
Circuits
Drive
3

Range

2
3

Tlmlnll
valve

For
2
3
shifts
a
restrictive
orifice

slows
the

application
fluid
to
the
front

clutch
while
the

slower

reacting
band

is
allowed
to
release
This

prevents
a

hard
2
3
or
3
2
shift
Under

heavy

load
however
the

engine
will
tend
to

run

away
during
the
2
3

or
3
2
shift

pause
therefore
a
2
3

timing
valve

using
throttle
and

governor

pressure
is

used
to

bypass
the

restrictive
orifice

during
such

heavy
load
conditions

Solenoid
down
hHt
valve

The
solenoid
downshift
valve
is

activated

electrically
when
the
ac

celerator
is
f1oor
d

causing
a
forced

downshift
from

top
to
second

top
to

first
or

second
to

first

gear
depending

upon
car

speed
governor

pressure

AT
3
Pre
ure
modified
valve

The

pressure
modifier

valve
assists

the
mainline

pressure

regulator
valve
in

lowering
mainline

pressure
during

high

speed

light
load
conditions
such
as

steady

speed
cruise

Governor

pres

sure

working

against
a

spring

opens

the

valve
which
aUows

modified
throt

tle

pressure
to
work

against
the

pres

sure

regulator
valve

spring
lowering

mainline

pressure
Lower

operating

pressure
under

light
load

reduces
oil

temperature
and
increases
transmis

sian
life

Throttle
back
up
valve

The
throttle

back

up
valve
assists

the
vacuum
throttle
valve
to

increase

line

pressure
when
the
manual
valve
is

shifted

either
to

2
or
I

range

Second
lock
valve

The

second
lock
valve
is

used
to

bypa
the
1
2

shift
valve

to
maintain

the
band

apply

pressure
in
2

posi

tion
The
valve
is
also
used
as
an
oil

passage
for
the
1
2

shift
valve

band

apply

pressure
in

D2

D3
and

12
Range

CLUTCHES
AND
BAND

SERVOS

The

servo

pistons
of
the
clutches

low

reverse
brake
and

band
are
moved

hydraulically
to

engage
the

clutches

brake
and

apply
the
band
The
clutch

and

brake
istons

are
released

by

spring
tension

and
band

piston
is

released

by
spring
tension

and

hy

draulic

pressure