KICKDOWN LIMIT VALVE
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 (Fig. 27) the limit valve does not come
into play and does not affect the downshifts. As the
vehicle’s speed increases (Fig. 28), the governor pres-
sure 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 bot-
toms 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
The 1–2 shift valve assembly (Fig. 29), or mecha-
nism, consists of: the 1–2 shift valve, governor plug,
and a spring on the end of the valve. After the man-
ual valve has been placed into a forward gear range,
line pressure is directed to the 1–2 shift valve. As the
throttle is depressed, throttle pressure is applied to
the right side of the 1–2 shift valve assembly. With
throttle pressure applied to the right side of the
valve, there is now both spring pressure and throttle
pressure acting on the valve, holding it against the
governor plug. As the vehicle begins to move and
build speed, governor pressure is created and is
applied to the left of the valve at the governor plug.
Fig. 27 Kickdown Limit Valve-Low Speeds
Fig. 28 Kickdown Limit Valve-High Speeds
21 - 26
42RE AUTOMATIC TRANSMISSION
WJ
DESCRIPTION AND OPERATION (Continued)