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AT-20
A/T CONTROL SYSTEM
Revision: August 20072004 QX56
Shift MechanismUCS002CD
The automatic transmission uses compact dual planetary gear systems to improve power-transmission effi-
ciency, simplify construction and reduce weight.
It also employs an optimum shift control and super wide gear ratios. They improve starting performance and
acceleration during medium and high-speed operation.
CONSTRUCTION
FUNCTION OF CLUTCH AND BRAKE
1. Front brake 2. Input clutch 3. Direct clutch
4. High and low reverse clutch 5. Reverse brake 6. Forward brake
7. Low coast brake 8. 1st one-way clutch 9. Forward one-way clutch
10. 3rd one-way clutch 11. Front sun gear 12. Input shaft
13. Mid internal gear 14. Front internal gear 15. Rear carrier
16. Rear sun gear 17. Mid sun gear 18. Front carrier
19. Mid carrier 20. Rear internal gear 21. Output shaft
22. Parking gear 23. Parking pawl
PCIA0002J
Name of the Part Abbreviation Function
Front brake (1) FR/B Fastens the front sun gear (11).
Input clutch (2) I/CConnects the input shaft (12), the front internal gear (14) and the mid internal
gear (13).
Direct clutch (3) D/C Connects the rear carrier (15) and the rear sun gear (16).
High and low reverse clutch (4) HLR/C Connects the mid sun gear (17) and the rear sun gear (16).
Reverse brake (5) R/B Fastens the rear carrier (15).
Forward brake (6) F/B Fastens the mid sun gear (17).
Low coast brake (7) LC/B Fastens the mid sun gear (17).
1st one-way clutch (8) 1st/O.CAllows the rear sun gear (16) to turn freely forward relative to the mid sun gear
(17) but fastens it for reverse rotation.
Forward one-way clutch (9) F/O.CAllows the mid sun gear (17) to turn freely in the forward direction but fastens it
for reverse rotation.
3rd one-way clutch (10) 3rd/O.CAllows the front sun gear (11) to turn freely in the forward direction but fastens
it for reverse rotation.
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A/T CONTROL SYSTEM
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CLUTCH AND BAND CHART
—Operates
—Operates during “progressive” acceleration.
—Operates and effects power transmission while coasting.
—Line pressure is applied but does not affect power transmission.
—Operates under conditions shown in HLR/C Operating Condition
—Operates under conditions shown in LC/B Operating Condition. Delay control is applied during D (4,3,2,1) N shift. Shift position I/C HLR/C D/C R/B FR/B LC/B Fwd/B1st
OWCFwd
OWC3rd
OWCRemarks
PPARK POSITION
RREVERSE
POSITION
NNEUTRAL POSI-
TION
D1st
Automatic shift
1⇔2⇔3⇔4⇔5 2nd
3rd
4th
5th
1st
42nd
Automatic shift
3rd1⇔2⇔3⇔4
4th
31st
Automatic shift
1⇔2⇔3⇐4 2nd
3rd
4th
21st
Automatic shift
1⇔2⇐3⇐4 2nd
3rd
4th
11st
Locks (held sta-
tionary in 1st
gear)
1⇐2⇐3⇐4 2nd
3rd
4th
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AT-22
A/T CONTROL SYSTEM
Revision: August 20072004 QX56
POWER TRANSMISSION
“N” Position
Since both the forward brake and the reverse brake are released, torque from the input shaft drive is not trans-
mitted to the output shaft.
“P” Position
The same as for the “N” position, both the forward brake and the reverse brake are released, so torque
from the input shaft drive is not transmitted to the output shaft.
The parking pawl linked with the select lever meshes with the parking gear and fastens the output shaft
mechanically.
LCIA0316E
1. Front brake 2. Input clutch 3. Direct clutch
4. High and low reverse clutch 5. Reverse brake 6. Forward brake
7. Low coast brake 8. 1st one-way clutch 9. Forward one-way clutch
10. 3rd one-way clutch 11. Front sun gear 12. Input shaft
13. Mid internal gear 14. Front internal gear 15. Rear carrier
16. Rear sun gear 17. Mid sun gear 18. Front carrier
19. Mid carrier 20. Rear internal gear 21. Output shaft
22. Parking gear 23. Parking pawl
PCIA0003J
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A/T CONTROL SYSTEM
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“D”, “4”, “3”, “2” Positions 1st Gear
The forward brake and the forward one-way clutch regulate reverse rotation of the mid sun gear.
The 1st one-way clutch regulates reverse rotation of the rear sun gear.
The 3rd one-way clutch regulates reverse rotation of the front sun gear.
During deceleration, the mid sun gear turns forward, so the forward one-way clutch idles and the engine
brake is not activated.
1. Front brake 2. Input clutch 3. Direct clutch
4. High and low reverse clutch 5. Reverse brake 6. Forward brake
7. Low coast brake 8. 1st one-way clutch 9. Forward one-way clutch
10. 3rd one-way clutch 11. Front sun gear 12. Input shaft
13. Mid internal gear 14. Front internal gear 15. Rear carrier
16. Rear sun gear 17. Mid sun gear 18. Front carrier
19. Mid carrier 20. Rear internal gear 21. Output shaft
22. Parking gear 23. Parking pawl
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AT-24
A/T CONTROL SYSTEM
Revision: August 20072004 QX56
“1 ” Position 1st Gear
The front brake fastens the front sun gear.
The forward brake and the forward one-way clutch regulate reverse rotation of the mid sun gear.
High and low reverse clutch connects the rear sun gear and the mid sun gear.
The low coast brake fastens the mid sun gear.
During deceleration, the low coast brake regulates forward rotation of the mid sun gear and the engine
brake functions.
1. Front brake 2. Input clutch 3. Direct clutch
4. High and low reverse clutch 5. Reverse brake 6. Forward brake
7. Low coast brake 8. 1st one-way clutch 9. Forward one-way clutch
10. 3rd one-way clutch 11. Front sun gear 12. Input shaft
13. Mid internal gear 14. Front internal gear 15. Rear carrier
16. Rear sun gear 17. Mid sun gear 18. Front carrier
19. Mid carrier 20. Rear internal gear 21. Output shaft
22. Parking gear 23. Parking pawl
SCIA1513E
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A/T CONTROL SYSTEM
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“D”, “4”, “3” Positions 2nd Gear
The forward brake and the forward one-way clutch regulate reverse rotation of the mid sun gear.
The 3rd one-way clutch regulates reverse rotation of the front sun gear.
The direct clutch is coupled and the rear carrier and rear sun gear are connected.
During deceleration, the mid sun gear turns forward, so the forward one-way clutch idles and engine
brake is not activated.
1. Front brake 2. Input clutch 3. Direct clutch
4. High and low reverse clutch 5. Reverse brake 6. Forward brake
7. Low coast brake 8. 1st one-way clutch 9. Forward one-way clutch
10. 3rd one-way clutch 11. Front sun gear 12. Input shaft
13. Mid internal gear 14. Front internal gear 15. Rear carrier
16. Rear sun gear 17. Mid sun gear 18. Front carrier
19. Mid carrier 20. Rear internal gear 21. Output shaft
22. Parking gear 23. Parking pawl
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AT-26
A/T CONTROL SYSTEM
Revision: August 20072004 QX56
“2”, “1” Position 2nd Gear
The front brake fastens the front sun gear.
The forward brake and the forward one-way clutch regulate reverse rotation of the mid sun gear.
The direct clutch is coupled, and the rear carrier and rear sun gear are connected.
The low coast brake fastens the mid sun gear.
During deceleration, the low coast brake regulates forward rotation of the mid sun gear and the engine
brake functions.
1. Front brake 2. Input clutch 3. Direct clutch
4. High and low reverse clutch 5. Reverse brake 6. Forward brake
7. Low coast brake 8. 1st one-way clutch 9. Forward one-way clutch
10. 3rd one-way clutch 11. Front sun gear 12. Input shaft
13. Mid internal gear 14. Front internal gear 15. Rear carrier
16. Rear sun gear 17. Mid sun gear 18. Front carrier
19. Mid carrier 20. Rear internal gear 21. Output shaft
22. Parking gear 23. Parking pawl
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A/T CONTROL SYSTEM
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“D”, “4”, “3” Positions 3rd Gear
The front brake fastens the front sun gear.
The direct clutch is coupled, and the rear carrier and rear sun gear are connected.
The high and low reverse clutch is coupled and the mid sun gear and rear sun gear are connected.
1. Front brake 2. Input clutch 3. Direct clutch
4. High and low reverse clutch 5. Reverse brake 6. Forward brake
7. Low coast brake 8. 1st one-way clutch 9. Forward one-way clutch
10. 3rd one-way clutch 11. Front sun gear 12. Input shaft
13. Mid internal gear 14. Front internal gear 15. Rear carrier
16. Rear sun gear 17. Mid sun gear 18. Front carrier
19. Mid carrier 20. Rear internal gear 21. Output shaft
22. Parking gear 23. Parking pawl
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