1975 Datsun 280z FSM - Spooled up Racing

"2" RANGE (2ND GEAR)
In "2" range the gear ratio is locked
in the 2nd forward speed. In this case,
the rear clutch is engaged and the band
brake holds the front clutch drum, the
connecting shell and sun gear from
rotating.
The power flow takes place through
the input shaft into the rear clutch
and the front internal gear. With the
sun gear held stationary, the front
planetary gears rotate around the sun
gear, carrying the front planet carrier
with them. The front planet carrier,
being splined to the output shaft,
causes clockwise rotation of the output
shaft at a reduced speed compared
to the speed of the input shaft, with
an increase in torque. As the low and
reverse brake is not engaged, the clockwise
rotation of the output shaft
causes clockwise rotation of rear internal
gear and the rear planet carrier also
rotates around the sun gear in a
clockwise direction. The one-way
clutch will act to allow clockwise
rotation of connecting drum.
When the manual valve (2) is positioned
at "2", the line pressure (7) is
introduced into the line pressure circuits
(1), (2) and (4). The line pressure
(1) is led to the governor, rear clutch
and "1st-2nd" shift valve (3) as in the
case of "D" range. The line pressure
(2) locks the second lock valve (9) and
is led to the tightening side of the
band servo.
The "2nd" gear is therefore fixed
regardless of vehicle speed. When
"D 3 " range (3rd gear) is shifted to "2"
range, the line pressure (4) enters the
throttle back-up valve® and produces
a high pressure in the circuit (17),
increasing the throttle pressure (16).
The line pressure (7) is, therefore,
increased and quickly tightens the
band.
Automatic
Park
Reverse
Neutral
Dl Low
Drive D2 Second
D3 Top
2 Second
12 Second
1
1 ] Low
Transmission
Gear
ratio
AT078
Fig. AT-40 Power transmission during "2"range
AT079
Fig. AT-41 Operation of each mechanism during "2" range
2.182
2.458
1.458
1.000
1.458
1.458
2.458
Clutch
Front
on
on
Rear
on
on
on
on
on
on
Low&
reverse
brake
on
on
on
Operation
on
(on)
on
on
Band servo
Release
on
on
One
way
clutch
on
Parking
pawl
on
Note: "D 3 " range (3rd gear) to "2"
range:
If "D3" range (3rd gear) is shifted
to "2" range during operation, the
manual valve (2) is also shifted to
"2" position, causing the line pressure
circuit (3) to be drained.
Therefore, the line pressure circuit
(10) which is situated at the release
side of the front clutch and servo is
also drained through the "2nd-3rd"
shift valve (4) , forcing the speed to
AT-28
decrease from "3rd gear" to "2nd
gear." In this case the speed change
quickly takes place because the line
pressure (7) and other pressure are
heightened by the action of the line
pressure (4), in the same manner as
described under "2" range.