1990 MITSUBISHI ECLIPSE Service Manual

AUTOMATIC TRANSAXLE - Transaxle Control21-75
From kickdown
servo apply side
1Shift control
valve
1-2 shift
1750237
11To low-reverse To low-reversebrake brake
‘1..‘; Line pressure.F: from manual valveDownshift from
2nd to 1st Gear
If the shift control valve is moved to the
1st gear position, the2nd pressure is released and the
l-2 shift valve is pushed to
the left by the spring force. This opens the exhaust port and the
pressrue that was acting on the kickdown servo is now
released through the No. 11 line.
In Reverse
When the manual valve is shifted to the reverse position, line
pressure is directed to the No. 16 port of the
1-2 shift valve by
way of the N-R control valve. The combination of a larger area
to which pressure is applied on the
#2 land and a smaller area
on the
# 1 land of the 1-2 shift valve causes the valve to move
to the right, thus opening the No. 17 line port.
Pressure is directed to the low-reverse brake through this
opened port.
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21-76AUTOMATIC TRANSAXLE - Transaxle Control
2-314-3 SHIFT VALVE
Rear clutchexhaust valve
Front clutchRear clutchKlckdown servo
release stdeKickdown servo
apply side
?I
l-2 shift
valve
control valve
_ To end- ciutch
valvet
Line pressure
1750238
II
i Line pressure1750105
To front clutch andI 1 kickdown servo 1 112 release side19n fln
IIT3rd
pressure
t- Line pressureThe
2-WI-3 shift valve operates in response to tine pressure
(3rd or 4th pressure) from the shift control valve, and controls
the pressure acting on the front and rear clutches, and also thekickdown servo release pressure.
Upshift from
2nd to 3rd Gear
When the 2-3/4-3 shift valve is free from hydraulic pressure.the valve is held pushed to the left by the spring force. In
thissituation. the No. 11 pan is closed, cutting off the line pressure
from the
1-2 shift valve. If the 3rd pressure is directed to the
2-3/4-3 shift valve through the No.7 line, the pressure forcesthe valve to the right, clearing the No.
11 port. This allows the
fine pressure from the l-2 shift valve to be directed via the
2-3/4-3 shift valve to the front clutch, kickdown sem(release
side), end clutch valve and rear clutch exhaust valve.

ir yAUTOMATIC TRANSAXLE
- Trahsaxle Control21-774th Gear
3rd GearRear clutchKickdown
1servo
release sideFront clutch
-
Rear clutch3rd1-2 shiftKickdown
Front clutch
q]b Ture,‘r z&eside
7
1750107
1Fromk-D3rd 14th pressure
control valve1 ;l;hiftpressure1750108
Upshift from
3rd to 4th Gear
.When the 4th pressure (line pressure) from the shift
control valve is directed to the rear clutch exhaust
valve through the No.8 line. the valve is pushed to
the right, closing the No.5c port. This cuts off the
pressure to the rear clutch and also releases the
pressure acting on the rear clutch through NO.
15port, No.20a port and No. 20
port.On the other hand, the rear clutch exhaust
valvewhich is pushed to the right opens the NO. 19
POnand directs the 4th pressure (line pressure) to the
right end of the
2-3/4-3 shift valve. The 3rdpressure (or the No.7 line pressure) is acting on theleft
end of the 2-3/4-3 shift valve. As this Pressure
..is equal to the No. 19 line pressure and acts on the
Mme area, the spring at the right end of the valveWhen the 4th pressure is released by the move-
ment of the shift control valve, the rear clutchDownshift from 4th to
3rd Gear
exhaust valve moves to the left, creating a
3rd gearstate, and the pressure is directed to the rear clutch.
At the same time as this happens, the 4th pressure
in No. 19 line which has been acting on the 2-3/4-3shift valve is released. This causes the
3rd pressure
established in the
No.7 line to push the 2-3/4-3shift valve to the right, and creates a 3rd gear state
where the line pressure from the
l-2 shift valve is
directed to the front clutch and the release side
chamber of kickdown servo cylinder through the
No. 12 line.shes the valve toward the
left. closing the No. 11me pressure port. This
btocks the pressure to the
front clutch and the release side chamber ofkickdown servo cylinder, and the pressure is re-
leased through the No. 12. and then the
No.9~ Pofi.

21-78AUTOMATIC TRANSAXLE - Transaxle Control
N-D CONTROL VALVE
.-.‘r
To rear clutch viarear clutch exhaust valve
N-Dcontrol
valve
EXpressure
Pressurecontrol
valve
t
Reducingpressure
t
Red”&pressure
175oz39
The purpose of this valve is to prevent shock from
occurring when shifting the select lever from “N” to
“D”. The valve supplies the rear clutch with the oilpressure regulated by the pressure control valve
only when the N-D shifting is being performed. After
the shifting is completed, the valve is switched over
to allow the line pressure to be supplied to the rear
clutch.
Selector Lever in ‘N”
When the manual valve is shifted to the “N” rangeposition, the line pressure from the oil pump is
directed to the N-D control valve through the No.4line. As the
#2 land has a slightly larger area to
which pressure is applied than that of the #3 land of
the N-D control valve, the movement of the valve
caused by the line pressure is toward the left, whichcloses the
No.5 port.

AUTOMATIC TRANSAXLE - Transaxle Control21-79
70 rear clutch via
rear clutch exhaustvalve
Frommanual valveOrifice
Line pressure From pressure
from manual
control valve
valve
175024
valveFrom manual
From pressure
valvecontrol valve175024Shift from “N” to
“D” .
When the manual valve is shifted from the “N” to the
“D”range position, the following sequence of events occur.
(1) The line pressure from the manual valve is distributed
through the No. 5 line to the NO. 5, NO. 5d and No. 5e lines ofthe N-D control
VdVe.
(2) The No.5 port is closed at this stage by the N-D control
valve.(3) There is a chamber with a check ball on the No.
5d line. Asthe check ball is held pressed against the downstream
opening of the chamber by the line pressure, the line
pressure passes through the
No.Se line, which has an
orifice provided.
(4 The line pressure, after being attenuated by the orifice, is
directed to the No.5c line.
(5) Meanwhile, the pressure from the pressure control valve
which has been regulated by the pressure control solenoid
valve is supplied through the No. 10 line.
(6) There is an orifice in the No. 10 line and the pressure which
is attenuated by passing through this orifice flows into the
No.
5c line.
(7) The No. 5c line pressure is directed to the rear clutch via therear clutch exhaust valve.
(8) If the rear clutch completes engagement, the duty setting
of the pressure control solenoid valve becomes zero
percent, increasing the pressure to the line pressure level.
(9) The line pressure thus established in the No.5c line works
on the N-D control valve to move it towards the right. This
rightward movement is’ caused by the difference in area to
which pressure is applied between the two lands.
(lO)The above movement of the N-D control valve opens theNo.5 port, and through the port, the line pressure estab-
lished in the No. 5 line flows into the No.
5c line and then is
directed to the rear clutch via the rear clutch exhaust valve.

21-80AUTOMATIC TRANSAXLE - Transaxle Control
VALVE WITH ORIFICE
When
oressureis releasedWhen pressure
-is applredTo rear clutch
via rear clutch
exhaust valveTo low-reverse brake
i
Ltne pressure1
- 2 shiftvalve
Ex
1750242If the accelerator pedal is depressed ‘immediately
after shifting the select lever from
“N” to “D”, the
rear clutch engages directly and the vehicle moves
in
1st gear. Due to the arrangement of the hydraulic
circuit, in thjs case, the hydraulic pressure is actuallydirected to both the rear clutch and the low-reverse
brake, thus dividing the quantity of the distributed
fluid. This in turn can cause a delay in clutchengagement when the fluid temperature is high. To
prevent this, a special valve is provided in the
low-reverse brake circuit. This valve has an orifice
which restricts flow of fluid when the pressure is
directed to the low-reverse brake but has no flow
restriction effect when the low-reverse brake press-
ure is released, thus preventing sluggish release of
the brake.

AUTOMATIC TRANSAXLE - Transaxle Control21-81
3 CLUTCH VALVE
To front clutch
.To end clutch
To kickdown
servo release
Shift
control
solenoid
valve
- BShift control
solenoid valve
-A
II
J
ExIPlug
End clutch valve
‘11 E”
Line pressure
1750243End clutch valve controls the timing for supplying hydraulic
pressure to the end clutch.In 2nd Gear
(1) When hydraulic pressure is not being directed to the end
clutch valve, it is held pushed to the left by the spring force
(see above figure).
(2) If the
2nd pressure from the shift control valve is directed
to the end clutch valve via the No.6 line, the end clutch
valve is forced toward the right.
,nd Gear
Lrom manualvalveTo end,&tch.
2ndpressurepressure
I17501i

21-82AUTOMATIC TRANSAXLE - Transaxle Control
valve
A
2nd3rdpressure pressure175011:To shift
control
valve#3
land
2nd3rdpressure pressure
175011~LlUpshift from
2nd to 3rd Gear\(1) When the shift control valve comes into
3rd gear position
and the
3rd pressure is established, the pressure is
directed to the No.7 port of the end clutch valve through
the No.7 line. In this instance, the
3rd pressure is blocked
ahead by the end clutch valve and the check ball.
(2) If a shift to the
3rd gear is initiated, the pressrue begins to
be directed from the
2-3/4-3 shift valve to the front clutch
and the release side chamber of kickdown servo cylinder.
The same pressure also is directed to the chamber at the
right end of the end clutch valve through the No. 12 line.
During the shift to the
3rd gear, the pressure in the No. 12
line is regulated by the pressure control valve to a level
lower than the line pressure so that the No. 12 line pressureis not high enough to force the end clutch valve toward the
left.(3) Once the front clutch has been engaged and the kickdown
brake released, the No. 12 line pressure is raised to a level .
equivalent to the line pressure.
This means that the pressures at both ends of the end
j
clutch valve (or No. 6 line pressure and No. 12 line pressure)[are at the same level. However, as the area of the
#3 land
to which pressure is applied is larger than that of the
# 1
land of the end clutch valve, the valve is pushed to left, thusopening the No.
18 port. This allows the 3rd pressure (line
pressure) already established in the No. 7 line to be directedto the end clutch through
the..No.7 port. The end clutch is
now engaged.
Downshift from
3rd to 2nd Gear
(1) Both front clutch pressure and kickdown servo release
pressure are released, and therefore, the pressure in
theend clutch valve right end chamber is also released.
--
(2) This results in a rightward movement of the end clutclvalve by the
2nd pressure working on its left end, closingthe
No.7 port and releasing the end clutch pressurethrough the No.8 port. Now the end clutch is released,
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