- When the central sun gear is locked in place, the planetary gears rotate around it. As a result, both the carrier and the outer ring gear rotate in the same direction.
- When the sun gear is locked to the outer ring gear, the planetary gears are unable to rotate. As a result, the carrier drives the entire assembly, causing the whole unit to turn together.
- When the planet carrier is locked, the sun gear rotates the planetary gears, which in turn drive the ring gear in the opposite direction.
First Gear
In first gear, the forward-drive clutch engages, causing the engine to rotate the first ring gear. This movement drives the planetary gears, which in turn rotate the common sun gear in the opposite direction. The second planet carrier is held stationary by a brake band, so the planetary gears drive the second ring gear and the output shaft. This setup results in two stages of speed reduction, effectively slowing down the engine’s rotational speed before transferring it to the wheels.
Second Gear
Second gear provides an intermediate speed ratio. Here, the forward-drive clutch is engaged, allowing the engine to drive the first ring gear. The sun gear is braked, causing the planetary gears to revolve around it. This action drives the planet carrier in the same direction as the engine. Since the planet carrier is directly connected to the output shaft, one stage of speed reduction is achieved. The second set of planetary gears and their carrier freewheels, not contributing to this gear ratio.
Top Gear
In top gear, the forward-drive clutch engages to drive the first ring gear, while the reverse clutch is also activated. This locks the ring gear to the sun gear, causing both to rotate at the same speed. As a result, the planetary gears are stationary, and the carrier rotates directly at engine speed. The output is taken from the carrier shaft, providing a direct drive with no additional speed reduction.
Reverse Gear
In reverse gear, the forward-drive clutch engages, and the engine drives the first ring gear. The reverse clutch also locks the ring gear to the sun gear, causing both to rotate at the same speed. With the planetary gears unable to turn, the carrier shaft also rotates at engine speed. Thus, the output is taken from the carrier shaft, providing a direct drive in reverse.
