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| Illustration 1 | g01702757 |
Components of the transmission (1) Input shaft (2) Clutch hub (3) Ring gear (4) Planetary gears (5) Planetary gears (6) Ring gear (7) Sun gear (8) Sun gear (9) Planetary gears (10) Ring gear (11) Ring gear (12) Planetary gears (13) Sun gear (14) No. 1 clutch (15) No. 2 clutch (16) Planetary carrier (17) No. 3 clutch rotating (18) No. 3 clutch housing (19) Center shaft (20) No. 4 clutch housing (21) No. 4 clutch rotating (22) No. 5 clutch (23) No. 6 clutch (24) Planetary carrier and output shaft | |
The planetary transmission has seven forward speeds. REVERSE and NEUTRAL use only torque converter drive. At lower ground speeds, FIRST gear and SECOND gear use torque converter drive. As the ground speed increases, the lockup clutch of the torque converter engages. This provides FIRST gear or SECOND gear with direct drive. Direct drive is engaged when the transmission is in THIRD gear through SEVENTH gear. There is a short period of torque converter drive when the clutches engage in the planetary transmission. This provides smooth, automatic upshifting from THIRD through SEVENTH gears. This provides smooth, automatic downshifting from SEVENTH through THIRD gears. The table below shows the clutches that are engaged for each gear.
| TH48-E70 SPEED SELECTION | |
|---|---|
| SPEED | ENGAGED CLUTCHES (= ENERGIZED VALVES) |
| Park | 4 and 6 |
| Neutral | 1 |
| Stall | 1, 4 and 6 |
| First Gear Forward | 2 and 6 |
| Second Gear Forward | 1 and 6 |
| Third Gear Forward | 3 and 6 |
| Fourth Gear Forward | 1 and 5 |
| Fifth Gear Forward | 3 and 5 |
| Sixth Gear Forward | 1 and 4 |
| Seventh Gear Forward | 3 and 4 |
The planetary transmission is bolted to the housing for the torque converter. Input shaft (1) for the planetary transmission is connected to the engine output shaft. The main drive shaft connects the planetary transmission with the transfer gears and case.
The planetary speed sensor measures the speed of the planetary transmission. The sensor sends the transmission speed to the ECM (Electronic Control Module).