Figure 2-3. Hydraulic system, first gear, straight travel operation-schematic view.

TM 9-2520-249-34&P

Figure 2-3. Hydraulic system, first gear, straight travel operation-schematic view.

a. Operational Circuits. This driving condition

pressure oil is allowed to surround the stem of the

throttle valve and escape into the throttle circuit. This

uses the same circuitry as neutral except that the low-

circuit directs the TV pressure oil to the area above the

range clutch is engaged, and the output pump is

lockup shift valve where it assists the spring in opposing

actuated.

upward movement of the valve. Thus, at full throttle,

b. Manual Selector Valve.

The valve is

engagement of the lockup clutch is delayed. (TV

moved toward the right until the retaining ball rests in

pressure will also help to downshift the lockup shift

the first-gear detent. This allows a main-pressure port

valve at higher turbine speeds at heavy throttle.)

(upper passage) to index with a low-range clutch apply

d. Output-driven Pressure Pump. Forward

port. The low-range circuit becomes charged, thus the

vehicle travel causes the output-driven pump to rotate.

low-range clutch is engaged.

This pump assists the input-driven pump in supplying

c. Throttle Valve and Throttle Valve

main-pressure oil to the transmission (fig. 2-1).

Regulator.

The throttle is advanced to the full-throttle position. At

this setting, above three-quarter throttle, regulated

2-16