521 D drive range first gear

With the selector lever in D range, engine torque is transmitted to the overdrive pinion gears via the out put shaft and pinion carrier. Torque is then split between the overdrive annular gear and the sun gear, both paths merging due to the engaged direct clutch. Therefore the overdrive pinion gears are prevented from rotating on their axes, causing the overdrive gear set to revolve as a whole without any gear ratio reduction at this stage. Torque is then conveyed from the overdrive annular gear to the intermediate shaft where it passes through the applied forward clutch plates to the annular gear of the forward gear set. The clockwise rotation of the forward annular gear causes the forward planet gears to rotate clockwise, driving the double sun gear counter clockwise. The forward planetary carrier is attached to the output shaft so that the planet gears drive the sun gear instead of walking around the sun gear. This anticlockwise rotation of the sun gear causes the reverse planet gears to rotate

Fig. 5.2 Longitudinally mounted four speed automatic transmission layout
Table 5.1 Clutch and brake engagement sequence

Drive

High and

Second gear

Forward

Overdrive

Low and

One way

clutch

reverse clutch

band brake

clutch

brake

reverse

clutch

Range

DC

(H + R)C

2GB

FC

ODB

brake (L + R)B

OWC

Ratio

P and N

First D

Applied

Applied

Applied

2.4:1

Second D

Applied

Applied

Applied

Applied

1.37:1

Third D

Applied

Applied

Applied

1:1

Fourth D

Applied

Applied

Applied

0.7:1

Reverse R

Applied

Applied

Applied

2.83:1

(ct] Fourth gear

Fig. 5.3 (a-e) Four speed and reverse automatic transmission for longitudinally mounted units

(ct] Fourth gear

Fig. 5.3 (a-e) Four speed and reverse automatic transmission for longitudinally mounted units

(a) Reverse gear

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