524 D drive range fourth or overdrive gear

In D range in fourth gear, the overdrive band brake, the high and reverse clutch and the forward clutch are engaged. Under these conditions, torque is conveyed from the input shaft to the overdrive carrier, causing the planet gears to rotate clockwise around the held overdrive sun gear. As a result, the overdrive annular gear will be forced to rotate clockwise but at a higher speed than the input overdrive carrier. Torque is then transmitted via the intermediate shaft to the forward planetary gear set which are then locked together by the engagement of the high and reverse clutch and the forward clutch. Subsequently, the gear set is compelled to rotate bodily as a rigid straight through drive. The torque then passes from the forward planet carrier to the output shaft. Hence there is a gear ratio step up by the overdrive planetary gear set of roughly 30%, that is, the output to input shaft gear ratio is about 0.7:1.

Fig. 5.4(a-e) Four speed and reverse epicycle gear set directional motion

5.2.5 R range — reverse gear (Figs 5.3(e) and 5.4(e))

With the selector lever in reverse position all three clutches and the low and reverse multiplate brake are engaged. Subsequently, engine torque will be transmitted from the input shaft through the locked overdrive gear set through the locked forward gear set via the intermediate shaft to the reverse sun gear in a clockwise direction.

Because the reverse planet carrier is held by the low and reverse multiplate brake, the planet gears are forced to rotate counterclockwise on their axes, and in doing so compel the reverse annular gear to also rotate counterclockwise. As a result, the output shaft, which is attached to the reverse annular gear, rotates counterclockwise, that is, in the reverse direction, to the input shaft at a reduction ratio of approximately 2.18:1.

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