Daihatsu 1997 Terios J100 Service Manual page 419

AT–18
8) 3-4 shift valve & 3-4 relay valve
•
3-4 relay valve
The relay valve changes the force applied to the shift valve, depending on the throttle opening angle.
The forces applied to the valve are the large spring force (force F
pushing to the right side) and throttle pressure q (force F
force (force F
S'
In cases where the throttle opening angle is less than approximately 20%, a condition of F
satisfied. Consequently, the force applied to the shift valve becomes F
In cases where the throttle opening angle is between approximately 20% and 85%, a condition of F
F is satisfied. Then, the relay valve moves to the right side, coming into contact with the shift valve.
TH
Consequently, the force applied to the shift valve becomes F
In cases where the throttle opening angle is more than 85%, the throttle pressure w (force F
the left side) is applied, thus satisfying a condition of F
returns to the left again. Consequently, the force applied to the shift valve becomes F
•
3-4 shift valve
The 3-4 shift valve allows or does not allow the line pressure be applied to the servo control valve and C2,
depending on conditions of the vehicle speed, throttle opening angle and overdrive switch, so as to per-
form gear shifting between the 3rd gear and the 4th gear.
1. When shifting from 3rd gear to 4th gear:
The forces applied to the 3-4 shift valve are the force generated by the relay valve (force F
the right side (= F
S
side).
When running at a low speed (F
t will be applied to the servo control valve and C2 via r. However, when running at a high speed (F
), the valve moves to the left side. Consequently, the line pressure which was applied via r will be
> F
R
drained. Thus, gear shifting to the 4th gear takes place.
Furthermore, when the overdrive is turned OFF, the line pressure (force F
applied to e. Therefore, a condition of F
move to the left side. (No gear shifting to the 4th gear will take place.)
2. When shifting from 4th gear to 3rd gear:
When the valve is located at the left side, the pressure-receiving diameter of the governor pressure i
becomes greater. As a result, the force (F
Consequently, the 4th-to-3rd gear shift point comes at a speed lower than the 3rd-to-4th gear shift
point.
Furthermore, when the overdrive is turned OFF, the line pressure (force F
applied to e and u. However, since a condition of F
the right side (gear shifting to the 3rd gear takes place), regardless of the vehicle speed and throttle
opening angle.
<Except for 4th gear>
3-4 relay valve
Small spring
q
Large spring
q
Throttle pressure , Throttle valve
w
Line pressure , From 2-4 timing valve (1st and 2nd gears)
Throttle pressure , From 2-4 timing valve
(Throttle opening angle of 85% or more)
e
Line pressure , From overdrive solenoid
(When overdrive is turned OFF with shift lever
set to Î, x or Ò range)
r
3-4 & select timing valve / To C2
Servo control valve / To C1, B1'
, or F + F , or F + F
S' TH S
< F ), the valve is located at the right side. Therefore, the line pressure
G R
G
3-4 shift valve
w e
t u
r
y
S
+ F .
S' TH
+ F > F
S KD S'
)), and governor pressure i (force F
KD
< F + F is always satisfied. Consequently, the valve will not
S L
) pushing the valve to the left side also becomes greater.
G'
< F + F
G' S L'
<4th gear>
3-4 relay valve
i i
Small spring
q
t
Line pressure , From manual valve
y
To B1
u
Line pressure , From overdrive solenoid
i
Governor pressure , From governor valve
pushing to the left side), small spring
pushing to the right side).
TH
.
S
+ F (F ). As a result, the relay valve
TH KD
+ F
S KD
pushing to the left
G
pushing to the right side) is
L
pushing to the right side) is
L'
is always satisfied, the valve moves to
3-4 shift valve
w e
t u
r
y
Large spring
(Î, x and Ò ranges)
(When overdrive is turned OFF
with shift lever set to
Î, x or Ò range)
≥ F
+ F is
S S' TH
≤ F
+
S S'
pushing to
KD
.
JAT00029-00000
pushing to
R
G
i i
JAT00030-00023