2

When the gear selector is placed in the 2−position, the second coast
brake (B1) is applied by way of the manual valve. When the second
coast brake is applied, it holds the sun gear from rotating in either
direction. Power flow is the same with the selector in 2," as when the
selector is in D" because the second coast brake is parallel to the
second brake and No. 1 one−way clutch.

However, when the transmission is being driven by the wheels on
deceleration, the force from the output shaft is transmitted to the front
carrier, causing the front planetary pinion gears to revolve clockwise
around the sun gear. Since the sun gear is held by the second coast
brake, the planetary gears walk around the sun clockwise and drive the
front planetary ring gear clockwise through the input shaft and torque
converter to the crankshaft for engine braking. In contrast, while in
second gear with the selector in D−position, the sun gear is held in the
counterclockwise direction only and the sun gear rotates in a clockwise
direction and there is no engine braking.

The advantage that 2−range has over D2" is that the engine can be
used to slow the vehicle on deceleration, and this feature can be used to
aid in diagnosis. For example, a transmission which does not have
second gear in D−position but does have second gear while manually
shifting can be narrowed to the second brake (B2) or No. 1 one−way
clutch (F1). These components and related hydraulic circuits become
the primary focus in our diagnosis.

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L

When the gear selector is placed in the L−position, the first and reverse
brake (B3) is applied through the position of the manual valve. The
first and reverse brake performs the same function as the No. 2 one−way
clutch (F2) does in the forward direction. When the first and reverse
brake (B3) is applied it holds the rear planetary gear carrier from
turning in either direction, whereas the No. 2 one−way clutch holds the
carrier in the counterclockwise direction only.

The advantage that the first and reverse brake has, is that engine
braking can be achieved to slow the vehicle on deceleration. In D1,"
only the No. 2 one−way clutch holds the carrier, so while decelerating,
the one−way clutch would release and no engine braking would occur.

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D range 3 gear

The forward clutch (C1) is applied in all forward gears and connects the input shaft to the front planetary ring gear as it does in all forward
gears. The direct clutch (C2) connects the input shaft to the common sun gear. By applying both the direct clutch and the forward clutch, we have
locked the ring gear and the sun gear to each other through the direct clutch drum and the input sun gear drum. Whenever two members of
the planetary gear set are locked together direct drive is the result.

Notice that the second brake (B2) is also applied in third gear; however, since the No. 1 one−way clutch (F1) does not hold the sun gear in the
clockwise direction, the second brake has no effect in third gear. So why is it applied in third gear? The reason lies in a downshift to second gear. All that is necessary for a downshift to second gear is to release the direct clutch (C2). The ring gear provides input torque and the sun gear is released. The carrier is connected to the output shaft and final drive so the output shaft tends to slow the carrier. The pinion gears rotate clockwise turning the sun gear counterclockwise until it is stopped by the No. 1 one−way clutch. The carrier provides the output to the final drive.

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D range second gear

The forward clutch (C1) connects the input shaft to the front planetary ring gear. The sun gear is driven in a counterclockwise direction in first gear and by simply applying the second brake (B2) the sun gear is stopped by the No. 1 one−way clutch (F1) and held to the case. When the sun gear is held, the front pinion gears driven by the ring gear walks around the sun gear and the carrier turns the output shaft.

The advantage of the No. 2 one−way clutch (F2) is in the automatic upshift and downshift. Only one multiplate clutch is applied or released to achieve an upshift to second gear or downshift to first gear.

Notice how the second brake (B2) and the one−way clutch (F1) both hold the sun gear in series. The second brake holds the outer race of the one−way clutch to the transmission case when applied. The one−way clutch prevents the sun gear from rotating counterclockwise only when the second brake is applied.

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D.2

First gear is unique because it uses both the front and rear planetary gear sets. The forward clutch (C1) is applied in all forward gears and drives the ring gear of the front planetary gear set. When the ring gear rotates clockwise, it causes the pinions to rotate clockwise since the sun gear is not held to the case. The sun gear rotates in a counterclockwise direction. The front planetary carrier, which is connected to the output shaft, rotates, but more slowly than the ring gear; so for practical purposes, it is the held unit.

In the rear planetary gear set, the carrier is locked to the case by the No. 2 one−way clutch (F2). Turning torque is transferred to the rear planetary by the sun gear, which is turning counterclockwise. With the carrier held, the planetary gears rotate in a clockwise direction and cause the rear planetary ring gear to turn clockwise. The rear planetary ring gear is connected to the output shaft and transfers torque to the drive wheels.

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