Section II. OPERATION OF HYDRAULIC SYSTEM

Section II. OPERATION OF HYDRAULIC SYSTEM

2-12. Hydraulic Schematics

schematics identify each circuit. Areas not colored

are usually filled with oil which is neither flowing

a. Full and Partial Schematics. A schematic

nor under pressure. Such areas are inactive,

diagram of the entire hydraulic system is illustrated

contribute nothing to hydraulic action, and may be

in figure 2-2. Eight partial schematics in color (fig.

disregarded.

2-3 through 2-10) illustrate the operation of the

hydraulic system under various conditions ex-

2-13. Torque Converter or Lockup Drive

plained in paragraphs 2-14 through 2-21.

b. Valve Positions.

The torque converter and lockup clutch must be

(1) In the partial schematics (fig. 2-3 through

considered as part of the hydraulic system since

2-10). valves and other moving parts are shown in

both require oil for operation. Therefore, in all

their proper positions for the conditions illustrated.

explanations of transmission operation, keep in

Some valves will be at either one extreme or the

mind that the input drive may be direct (through

other of their movement, while others are at some

the applied lockup clutch) or hydraulic (through

intermediate position. Thus, those at intermediate

the torque converter). These terms are reduced to

positions show only the approximate degree of

"lockup" and "converter" operation in the ex-

movement under certain conditions.

planations which follows.

(2) It must be remembered that input speed,

2-14. Hydraulic System -- Neutral Operation

output speed. throttle opening, selector position,

a. Main Pressure Circuit (red--fig. 2-3).

and oil temperature and viscosity will affect the

(1) Engine idling. Figure 2-3 illustrates

degree of movement and positions of certain valves.

neutral operation of the transmission while the

c. Colors Indicate Hydraulic Circuits. Separate

engine is idling and the engine throttle is closed.

colors or color combinations indicate each

The transmission is in converter operation.

hydraulic circuit. Color blocks on the partial

2-7