Planetary Gearsets

This transmission has 2 planetary gearsets (front and rear) to provide operation in reverse and 6 forward speeds.

The front planetary gearset is a single planetary gearset and has the following components:

• Front planetary No. 1 sun gear
• Front planetary carrier
• Front planetary ring gear (part of the input shaft assembly)

The input shaft rotates the front ring gear as a driving member. The front sun gear is connected to the fluid pump and is held stationary. The front ring gear rotates the front planetary carrier assembly with a reduction ratio of 1.52:1.

The front planetary carrier assembly is the only output member of the front planetary gearset in reverse, 1st gear, 2nd gear and 3rd gear. The front planetary gearset provides a 1.52:1 gear reduction ratio to the rear planetary gearset.

In 4th gear and 5th gear, both the input shaft and front planetary carrier assembly are output members of the front planetary gearset. The front planetary gearset provides both a 1:1 and 1.52:1 gear ratios to different members of the rear planetary gearset.

In 6th gear, the input shaft is the only output member of the front planetary gearset. The input shaft provides a 1:1 gear ratio to the rear planetary gearset.

The rear planetary gearset is a ravigneaux planetary gearset and has the following components:

• Rear planetary No. 2 sun gear
• Rear planetary No. 3 sun gear
• Rear planetary carrier assembly (2 sets of pinion gears)
• Rear planetary ring gear assembly

Powerflow through the rear planetary gearset is as follows:

• In reverse, rear sun gear No. 2 is driven, the rear planetary carrier is held and the ring gear is the output at an overall transmission reduction gear ratio of 3.128:1
• In 1st gear, sun gear No. 3 is driven, the rear planetary carrier is held and the ring gear is the output at an overall transmission reduction gear ratio of 3.974:1
• In 2nd gear, sun gear No. 3 is driven, sun gear No. 2 is held and the ring gear is the output at an overall transmission reduction gear ratio of 2.318:1
• In 3rd gear, sun gear No. 3 and sun gear No. 2 are driven and the ring gear is the output at an overall transmission reduction gear ratio of 1.516:1
• In 4th gear, sun gear No. 3 and the rear planetary carrier are driven and the ring gear is the output at an overall transmission reduction gear ratio of 1.149:1
• In 5th gear, sun gear No. 2 and the rear planetary carrier are driven and the ring gear is the output at an overall transmission overdrive gear ratio of 0.858:1
• In 6th gear, the rear planetary carrier is driven, sun gear No. 2 is held and the ring gear is the output at an overall transmission overdrive gear ratio of 0.674:1

Fig 1: Identifying Front And Rear Planetary Gearset Components

Courtesy of FORD MOTOR CO.