5A
A/T Description
This automatic transmission is electronic control full automatic transmission with forward 4-speed and reverse 1-speed.
The torque converter is a 3-element, 1-step and 2-phase type and is equipped with an automatically controlled lock-up mechanism.
The gear change device consists of a ravigneau type planetary gear unit, 3 multiple disc type clutches, 3 multiple disc type brakes and 2 one-way clutches.
The hydraulic pressure control device consists of a valve body assembly, pressure control solenoid valve (linear solenoid), 2 shift solenoid valves, TCC (lock-up) solenoid valve and a timing solenoid valve. Optimum line pressure complying with engine torque is produced by the pressure control solenoid valve in dependence upon control signal from transmission control module (TCM). This makes it possible to control the line pressure with high accuracy in accordance with the engine power and running conditions to achieve smooth shifting characteristics and high efficiency.
A clutch-to-clutch control system is provided for shifting between 3rd gear and 4th gear. This clutch-to-clutch control system is made to function optimally, so that hydraulic pressure controls such as shown below are conducted.
• When upshifting from 3rd gear to 4th gear, to adjust the drain hydraulic pressure at releasing the forward clutch, a timing solenoid valve is used to switch a hydraulic passage with an orifice to another during shifting.
• When downshifting from 4th gear to 3rd gear, to adjust the line pressure applied to the forward clutch at engaging the forward clutch, a timing solenoid valve is used to switch a hydraulic passage with an orifice to another during shifting.
• When upshifting from 3rd gear to 4th gear with engine throttle opened, to optimize the line pressure applied to the forward clutch at releasing the forward clutch, the learning control is processed to compensate the switching timing of the timing solenoid at every shifting.
• When downshifting from 4th gear to 3rd gear with engine throttle opened, to optimize the line pressure applied to the forward clutch at engaging the forward clutch, the learning control is processed to compensate the line pressure every shifting.
Employing a ravigneau type planetary gear unit and this clutch-to-clutch control system greatly simplifies the construction to make possible a lightweight and compact transmission.
A line pressure learning control is conducted to provide optimum shifting time at every upshifting with engine throttle opened. If long upshifting time is detected, the subsequent line pressure applied during upshifting is intensified. On the contrary, if short upshifting time is detected, the subsequent line pressure applied during upshifting is weakened.
1. Torque converter clutch (TCC) 7. Rear sun gear 13. One-way No.1 clutch
2. Torque converter 8. Planet carrier 14. 2nd brake
3. Short planet pinion 9. Output shaft 15. Forward clutch
4. Front sun gear 10. Direct clutch 16. O/D and 2nd coast brake
5. Long planet pinion 11. 1st and reverse brake 17. Reverse brake
6. Ring gear 12. One-way No.2 clutch 18. Input shaft
Specifications
Item Specifications
Torque converter Type
 
Stall torque ratio 		3-element, 1-step, 2-phase type (with TCC Clock-up mechanism)
2.2
Oil pump Type
Drive system 		Internal involute gear type oil pump (non crescent type)
Engine driven
Gear change device Type Forward 4-step, reverse 1-step planetary gear type
Shift position “P” range Gear in neutral, output shaft fixed, engine start
“R” range Reverse
“N” range Gear in neutral, engine start
“D” range (O/D ON) Forward 1st ↔ 2nd ↔ 3rd ↔ 4th
automatic gear change
“3” range Forward 1st ↔ 2nd ↔ 3rd ← 4th
automatic gear change
“2” range Forward 1st ↔ 2nd ← 3rd
automatic gear change
“L” range Forward 1st ← 2nd ← 3rd reduction, and fixed at 1st gear
Gear ratio 1st 2.875 Number of teeth Front sun gear: 24
Rear sun gear: 30
Long planet pinion: 20
Short planet pinion: 19
Ring gear: 69
2nd 1.568
3rd 1.000
4th (overdrive gear) 0.696
Reverse (reverse gear) 2.300
Control elements Wet type multiple-disc clutch... 3 sets
Wet type multiple-disc brake... 3 sets
One-way clutch... 2 sets
Final gear reduction ratio 4.091
Lubrication Lubrication system Force feed system by oil pump
Cooling Cooling system Radiator assisted cooling (water-cooled)
Fluid used DEXRON®-III