Converter Pressure

TM 10-3930-633-34

vacuum drops, the spring-loaded diaphragm

b. Converter Pressure. Like control pressure,

converter pressure is regulated by the converter

moves the pushrod to open the throttle valve and

pressure regulator valve spring and is adjusted to

increase the throttle pressure.

driving conditions by compensator pressure and

e. Neutral.

selector lever positions.

(1) The manual valve at N selector lever

c. Manual Valve. Line pressure is delivered to

position blocks the fluid flow to both clutches and

the manual valve through a single passage; the

both bands. With no fluid pressure in the clutches

valve is positioned in the valve body by the

or servos, the clutches and bands are released by

m a n u a l linkage, according to the mode of

spring pressure, preventing power being trans-

operation desired. Fluid is distributed from the

mitted to the transmission output shaft.

manual valve through the following passages.

(2) Neutral operation of the transmission

(1) The D passagecharged in D range only.

keeps control pressure up to its proper value,

The D passage supplies fluid to the downshift

maintains a full torque converter, lubricates the

valve, and through the 1-2 shift shuttle ball check

transmission, and maintains a flow of fluid

valve to the 1-2 shift valve. In addition, fluid is

through the cooling system.

directed to the 2-3 shift orifice and through it to

f. D, Low Gear.

the 2-3 shift valve and to the bottom of the rear

(1) The 1-2 shift occurs when governor

servo lockout valve.

pressure force on the 1-2 shift valve overcomes

shift plug pressure and spring forces. The 1-2

(2) The D-2-1 passagecharged in Drive

range, manual Second gear (2 range) and manual

valve moves inward, exhausting the fluid which

low gear (1 range). The D-2-1 passage directs

holds the transition valve closed. The transition

apply fluid to the forward clutch, applying it, and

valve opens and admits control pressure to apply

to the upper end of the transition valve, to the

the front band.

governor valve and to the compensator cut back

(2) The front clutch remains on, and the front

band applied to put the transmission in second

valve.

(3) The 2-1-R-P passagescharged in 2, 1

gear.

g. D, High Gear. The 2-3 shift occurs when

and Reverse. The 2-1-R-P passage supplies fluid

governor pressure force overcomes spring and

to the upper valley of the 1-2 shift valve, and

shift plug pressure force at the 2-3 shift valve.

passes through the 1-2 shift valve bore to the

When the shift valve opens, control pressure

adj scent ends of the 1-2 shift accumulator and

flows through it to apply the rear clutch and

lockout valves.

(4) The 1-R-P passagescharged in 1, and

release the front band. With both clutches ap-

plied, the transmission is in third gear.

Reverse. The 1-R-P passage supplies fluid to the

valley of the 2-1 scheduling valve and through the

h. Low Gear.

1-2 shift shuttle ball check valve to the 1-2 shift

(1) When the manual valve is at the 2 selector

valve.

lever position, control pressure to the 1-2 shift

valve is cut off. This condition permits control

(5) The R Passage charged in R range only.

pressure to flow through the transition valve to

The R passage supplies fluid to the left valley of

apply the front band.

the throttle valve and to the upper valley of the 2-

(2) With the front clutch and the front band

3 shift valve.

applied, the transmission operates in first gear.

d. Throttle Pressure.

i. D Range, 2-1 Kickdown. When the ac-

(1) Throttle pressure adjusts the trans-

celerator pedal is depressed through the detent,

mission operation to engine torque. Throttle

the down-shift valve opens a passage that admits

pressure is produced from control pressure by the

control pressure behind the 1-2 shift plug to

throttle valve. The throttle valve is controlled by

oppose governor pressure. If the transmission is

a spring-loaded vacuum diaphragm unit mounted

in high and road speed is below 47-69 mph, the 2-3

on the rear of the transmission case.

valve will be forced closed against governor

(2) The vacuum diaphragm is actuated by the

pressure. When the 2-3 valve closes, control

engine intake manifold vacuum working against

pressure which has been applying the rear clutch

spring pressure. When the vacuum is higher than

and releasing the front band is exhausted. The

16 inches, the diaphragm moves against spring

apply pressure that was in the front servo in third

pressure and moves the pushrod away from the

gear is now free to apply the front band. As soon

throttle valve to cut off the throttle pressure

as the front band applies, the transmission is in

regulation. As the engine throttle is advanced,

second gear.

manifold vacuum will fall below 16 inches. As the

7-4