OVERALL SYSTEM
AT-41
[RE4F04B]
D
E
F
G
H
I
J
K
L
M
A
B
AT
Revision: November 2006
2006 Altima
The torque converter clutch piston is designed to slip to adjust the
ratio of ON-OFF, thereby reducing lock-up shock.
OFF-time INCREASING
↓
Amount of drain DECREASING
↓
Pilot pressure HIGH
↓
Lock-up RELEASING
Torque Converter Clutch Control Valve Operation
LOCK-UP RELEASED
The OFF-duration of the torque converter clutch solenoid valve is long, and pilot pressure is high. The pilot
pressure pushes the end face of the torque converter clutch control valve in combination with spring force to
move the valve to the left. As a result, converter pressure is applied to chamber A (torque converter clutch pis-
ton release side). Accordingly, the torque converter clutch piston remains unlocked.
LOCK-UP APPLIED
When the OFF-duration of the torque converter clutch solenoid valve is short, pilot pressure drains and
becomes low. Accordingly, the control valve moves to the right by the pilot pressure of the other circuit and
converter pressure. As a result, converter pressure is applied to chamber B, keeping the torque converter
clutch piston applied.
Also smooth lock-up is provided by transient application and release of the lock-up.
OVERRUN CLUTCH CONTROL (ENGINE BRAKE CONTROL)
Forward one-way clutch is used to reduce shifting shocks in downshifting operations. This clutch transmits
engine torque to the wheels. However, drive force from the wheels is not transmitted to the engine because
the one-way clutch rotates idle. This means the engine brake is not effective.
The overrun clutch operates when the engine brake is needed.
Overrun Clutch Operating Conditions
SAT011J
AAT155A
SAT014J
Selector lever position
Gear position
Throttle opening
D
D
1
, D
2
, D
3
Less than 3/16
2
2
1
, 2
2
1
1
1
, 1
2
At any position