Jeep cherokee 2000 Service Manual page 1020

21 - 112 AUTOMATIC TRANSMISSION—30RH
DESCRIPTION AND OPERATION (Continued)
2–3 valve is ready to make its shift. Now that the
vehicle is in motion and under acceleration, there is
throttle pressure being applied to the spring side of
the valve and between lands #3 and #4.
As vehicle speed increases, governor pressure
increases proportionately, until it becomes great
enough to overcome the combined throttle and spring
pressure on the right side of the valve. When this
happens, the governor plug is forced against the shift
valve moving it to the right. The shift valve causes
land #4 to close the passage supplying throttle pres-
sure to the 2–3 shift valve. Without throttle pressure
present in the circuit now, the governor plug will
push the valve over far enough to bottom the valve in
its bore. This allows land #2 to direct line pressure to
the front clutch.
After the shift (Fig. 31), line pressure is directed to
the land between the shift valve and the governor
plug, and to the release side of the kickdown servo.
This releases the front band and applies the front
clutch, shifting into third gear or direct drive. The
rear clutch remains applied, as it has been in the
other gears. During a manual"1" or manual "2" gear
selection, line pressure is sent between the two lands
of the 2–3 governor plug. This line pressure at the
governor plug locks the shift valve into the second
gear position, preventing an upshift into direct drive.
The theory for the blocking of the valve is the same
as that of the 1–2 shift valve.
THROTTLE VALVE
In all gear positions the throttle valve (Fig. 32) is
being supplied with line pressure. The throttle valve
meters and reduces the line pressure that now
becomes throttle pressure. The throttle valve is
moved by a spring and the kickdown valve, which is
mechanically connected to the throttle. The larger
the throttle opening, the higher the throttle pressure
(to a maximum of line pressure). The smaller the
throttle opening, the lower the throttle pressure (to a
minimum of zero at idle). As engine speed increases,
the increase in pump speed increases pump output.
The increase in pressure and volume must be regu-
lated to maintain the balance within the transmis-
sion. To do this, throttle pressure is routed to the
reaction area on the right side of the throttle pres-
sure plug (in the regulator valve).
Fig. 30 2–3 Shift Valve-Before Shift
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