Planetary Gear Trains
| ITEM | DESCRIPTION |
|---|---|
| 1 | Gear set 1 |
| 2 | Gearset 2 |
| 3 | Gear set 3 |
| 4 | Gear set 4 |
The planetary gear trains used on the 9HP48 transmission comprise four planetary gear sets; GS1, GS2, GS3 and GS4.
Engine torque is transferred, via operation of single or combinations of multiplate clutches, multiplate brakes and two dog clutches, to the four planetary gear trains. The gear trains are controlled by reactionary inputs from the multiplate clutches to produce the nine forward gears and one reverse gear. The gear ratios are as follows:
| GEAR | 1ST | 2ND | 3RD | 4TH | 5TH | 6TH | 7TH | 8TH | 9TH | REVERSE |
|---|---|---|---|---|---|---|---|---|---|---|
| Ratio | 4.713 | 2.842 | 1.909 | 1.382 | 1.00 | 0.808 | 0.699 | 0.580 | 0.480 | 3.830 |
Sun gear S2 of gear set GS2 has additional internal gearing and also operates as the ring gear R1 of gear set GS1.
Ring gear R3 is connected to planet carrier PC1 and PC2 and therefore rotates in the same direction and speed as the planet carrier.
Gear sets GS3 and GS4 are connected via a joint sun gear S3/S4 as a Simpson planetary gear set.
Ring gear R4 is connected to planet carrier PC3 and therefore rotates in the same direction and speed as the planet carrier.
Final output from the transmission occurs via gear set GS4 via a spur gear to the differential.