Dodge 2001 Ram 1500 Owner's Manual page 2079

21 - 444 AUTOMATIC TRANSMISSION - 44RE
VALVE BODY (Continued)
1-2 SHIFT CONTROL VALVE
It contains a valve with four lands and a spring. It
is used as both a "relay" and "balanced" valve.
The valve has two specific operations (Fig. 255):
• Aid in quality of the 1-2 upshift.
• Aid in the quality and timing of the 3-2 kick-
down ranges.
When the manual valve is set to the DRIVE posi-
tion and the transmission is in the first or second
gear range, 1-2 shift control or "modulated throttle
pressure" is supplied to the middle of the accumula-
tor piston by the 1-2 shift control valve. During the
1-2 upshift, this pressure is used to control the kick-
down servo apply pressure that is needed to apply
the kickdown and accumulator pistons. Thus, the 1-2
shift point is "cushioned" and the quality is
improved. During a WOT kickdown, kickdown pres-
sure is applied between the kickdown valve and the
1-2 shift control valve. This additional pressure is
directed to the 1-2 shift control's spring cavity, add-
ing to the spring load on the valve. The result of this
Fig. 253 1-2 Shift Valve-Before Shift
Fig. 254 1-2 Shift Valve-After Shift
increased "modulated" throttle pressure is a firmer
WOT upshift.
2-3 SHIFT VALVE
The 2-3 shift valve mechanism (Fig. 256) consists
of the 2-3 shift valve, governor plug and spring, and
a throttle plug. After the 1-2 shift valve has com-
pleted its operation and applied the front band, line
pressure is directed to the 2-3 shift valve through the
connecting passages from the 1-2 shift valve. The line
pressure will then dead–end at land #2 until the 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. Since the
throttle pressure end of the 2-3 shift valve is larger
in diameter than the 1-2 shift valve, the 2-3 shift will
always happen at a greater speed than the 1-2 shift.
BR/BE