RAM 3500 HD Truck 2WD L6-6.7L DSL Turbo (2008)
groove of the 2-3 shift valve (which will be in the direct drive position to the right).
After passing the annular groove, the fluid is routed to the spring end of the 2-3 shift valve. Fluid pressure reacting on the area of land #1 overcomes
governor pressure, downshifting the 2-3 shift valve into the kickdown, or second gear stage of operation. The valve is held in the kickdown position by
throttle pressure routed from a seated check ball (#2). Again, if vehicle speed is low enough, throttle pressure will also push the 1-2 shift valve left to seat
its governor plug, and downshift to drive breakaway.
KICKDOWN LIMIT VALVE
Kickdown Limit Valve - Low Speeds
The purpose of the limit valve is to prevent a 3-2 downshift at higher speeds when a part-throttle downshift is not desirable. At these higher speeds only a
full throttle 3-2 downshift will occur. At low road speeds the limit valve does not come into play and does not affect the downshifts.
Kickdown Limit Valve - High Speeds
As the vehicle's speed increases, the governor pressure also increases. The increased governor pressure acts on the reaction area of the bottom land of the
limit valve overcoming the spring force trying to push the valve toward the bottom of its bore. This pushes the valve upward against the spring and
bottoms the valve against the top of the housing. With the valve bottomed against the housing, the throttle pressure supplied to the valve will be closed
off by the bottom land of the limit valve. When the supply of throttle pressure has been shut off, the 3-2 part throttle downshift plug becomes inoperative,
because no pressure is acting on its reaction area.
1-2 SHIFT VALVE
1-2 Shift Valve - Before Shift
