Hydraulic System-High-Range Operation (Selector at 1-2-3 Position

g. Throttle (T) Circuit (green, yellow -- fig. 2-5).

trimmer plug to the lower end of its bore. Then

The throttle (T) circuit functions as described in

main pressure increases to full value.

paragraph 2-15g.

(7) The overall action of the trimmer is to

reduce clutch apply pressure momentarily after a

h. Inhibitor Pressure Circuit (dotted red--fig. 2-

gear change to prevent shift shock. It does this by

5). In intermediate range (selector at 1-2 position),

gradually applying main pressure at a rate which is

only the high-intermediate downshift inhibitor

circuit is charged. It functions as described in

influenced by throttle opening. The temporarily

reduced main pressure allows the clutch to slip

paragraph 2-15 h.

when it is initially applied.

i. Lockup Clutch Circuit (blue, white--fig. 2-5).

(1) The flow valve controls the lockup clutch

2-17.

Hydraulic

System--High-Range

circuit when a shift from one range to another

Operation (Selector at 1-2-3 Position

occurs automatically or is made manually. In figure

a. Main Pressure Circuit (red--fig. 2-6.)

2-5, the change can be considered as a manual

(1) Main-pressure circuit in high-range

change from selector position 1 to selector position

(selector at 1-2-3 position) is the same as that for

1-2, or it can be considered as an automatic upshift

intermediate-range (para 2-16a) except that line 4

from 1 to 2 within selector position 1-2.

is not charged, and the trimmer is not in operation.

(2) The downward movement of the flow valve

(2) The absence of pressure in the high-

(a (1) (c) and (d) above) releases the lockup clutch

intermediate inhibitor circuit (fed by line 4) per-

temporarily and triggers the action of the trimmer

mits the intermediate-high blocker plug, shift valve,

valve. The flow valve moves downward when the

and shift plug to move upward. This connects main

shift has just occurred. It will stay downward until

pressure, at the intermediate-high shift valve, to the

the oncoming clutch (intermediate range) is

high-range clutch line.

partially pressurized.

(3) When tbe trimmer is not acting, the flow

(3) When the flow valve is downward, lockup

valve is upward and the trimmer is charged as

pressure is released. This is only temporary until

explained in paragraph 2-15a (12) and (13), above.

the oncoming range clutch is filled and main

b. Converter-In Circuit (yellow--fig. 2-6). The

pressure above and below the flow valve equalizes.

converter-in circuit functions as described in

(4) Main pressure below the trimmer valve

paragraph 2-15b.

quickly lifts the trimmer valve until oil escapes

c. Front Governor (G1) Circuit (blue, black--

through the exhaust port at the left. This reduces

fig. 2-6). The front governor (G1) circuit functions

main pressure flowing to the clutch being applied.

as described in paragraph 2-15c.

With negligible pressure above the trimmer plug,

d. Rear Governor (G2) Circuit (green, black--

main pressure flowing through the orifice in the

fig. 2-6). The rear governor (G2) circuit functions

bottom of the trimmer valve forces the trimmer

as described in paragraph 2-15d, except that in-

plug upward, away from the trimmer valve. The

creased G2 pressure, in the absence of both in-

speed of its movement upward is influenced by

termediate-low and high-intermediate inhibitor

throttle valve (TV) pressure being faster at closed

pressure, has shifted the transmission to high range.

throttle (para. 2-15 f(4)). The speed of its

This occurred when G2 pressure forced the low-

movement likewise influences clutch apply pressure

intermediate and intermediate-high blocker plugs,

initially. The higher TV pressure is, the higher

shift valves, and shift plugs upward in their bores.

initial clutch pressure is.

e. High-Range Clutch Circuit (red, green--fig. 2-

(5) The trimmer valve remains open (oil

6). The high-range clutch circuit is charged by the

exhausting at left side) until the trimmer plug

main pressure circuit at the intermediate-high shift

reaches the top of its stroke. When the trimmer

valve bore when the valve is in its upward position.

plug stops, oil continues to flow upward through

Intermediate-range clutch pressure is exhausted

the orifice in the bottom of the trimmer valve.

through an orifice which relates the rate of

When pressure above and below the trimmer valve

disengagement of the intermediate-range clutch.

is equalized, spring pressure pushes the trimmer

f. Throttle Valve (TV) Circuit (blue, yellow--fig.

valve downward. This closes the exhaust port.

2-6) The throttle valve (TV) circuit functions as

Main pressure increases significantly below the

described in paragraph 2-15f

flow valve to return the flow valve to its upward

g. Lockup Clutch Circuit (blue, white--fig. 2-6).

position and lockup pressure is restored. Main

The lockup clutch circuit functions as described in

pressure is restored, at the same time, to the area

paragraph 2-15i

above the extender valve ball.

2-18. Hydraulic System--High-Range Oper-

(6) When the extender valve ball is seated,

ation (Selector at 2-3 Position)

further flow of oil from tbe upper area of the

trimmer valve bore is prevented. Then, oil entering

a. Low-Range Locked Out (fig. 2-7). When the

the bore (from main), through an orifice, forces the

2-17