CHAPTER 2. DESCRIPTION AND OPERATION - TM-9-2520-249-34-P0009

TM 9-2520-249-34&P

CHAPTER 2

DESCRIPTION AND OPERATION

Section I. DESCRIPTION AND OPERATION OF TRANSMISSION COMPONENTS

cover assembly (5) and pump (97), which are bolted

2-1.

Torque Converter and Lockup Clutch

together. Nonmetallic lockup clutch disk (13) reacts

a. Description

Torque

Converter

against the surface of the back plate when the lockup

Components (FO-3)

clutch is applied

(1) The torque converter includes three

c. Operation of Torque Converter and Lockup

main components-pump, turbine, and stator. The other

Clutch (FO-3)

parts in this group provide the support and housing for

(1) The torque converter and lockup

these three main components

clutch are inter-related and serve as the input member

(2) pump assembly (93, FO-3) is the

for the transmission. The action of these components,

driving element of the torque converter. The pump is

in combination, provides the functions of a torque

bolted to converter cover assembly (5) which is driven

multiplier, fluid coupling, and a direct drive coupling.

by the engine flywheel. The pump rotates on a double

(2) Engine torque is transmitted to

row ball bearing (99) supported by converter ground

converter cover assembly (5, FO-3). Converter pump

sleeve (45) which is bolted to converter housing (60)]

cover assembly (5), lockup clutch piston assembly (11),

(3) Converter turbine assembly (17) is the

lockup clutch back plate (15), and converter pump

driven element. It is splined to converter output shaft

assembly (93) rotate as a unit. Stator assembly (19) is

(39) which transmits torque to the high-range clutch

located between pump assembly (93) and turbine

housing, and intermediate- and low-range sun gears.

assembly (17). The turbine assembly and lockup clutch

The turbine hub is splined to the lockup clutch disk

disk (13) rotate as a unit with the converter turbine shaft.

(4) Stator assembly (19) is the reaction

(3) The cavity in which the torque

element. It is mounted on an over-running clutch on a

converter components are inclosed is continually

freewheel roller race assembly (24) which is splined to

charged with oil which circulates to the oil cooler and

ground sleeve (45). The stator is free to rotate in the

returns through the transmission sump and oil pressure

direction of engine rotation but locks up in the opposite

pumps. When the engine idles, there is little movement

direction.

imparted to the oil. Thus, during idle, the converter acts

b. Description

Lockup

Clutch

as a disengaged clutch. The pressure of the oil in the

Components(FO-3)

converter cavity keeps the lockup clutch piston in the

(1) The lockup clutch includes three main

released position during idle and low speeds.

components-piston assembly, clutch disk, and back

(4) When the engine is accelerated, the

plate. The lockup clutch, when engaged, provides direct

vanes of the converter pump force the oil radially

drive from the engine to the converter output shaft

outward and forward between the vanes of the turbine.

(2) Piston assembly (11, FO-3) is a spring

The impact of the accelerated oil against the turbine

steel diaphragm with a clutch apply disk attached at its

vanes causes the turbine to rotate, driving the converter

circumference. The piston assembly is mounted within

turbine shaft. Within the turbine, the oil flows toward the

converter pump cover assembly (5) and retained by a

turbine hub and then rearward. As the oil exits from the

snapring. The ends of the pump cover drive bolts nest

turbine, it passes between the vanes of the stator and

in recesses in the lockup piston, causing the piston and

returns to the inner circumference of the converter

pump cover to rotate as a unit

pump However, when the pump is rotating faster than

(3) Lockup clutch disk (13) is a

the turbine the returning oil strikes the front of the stator

nonmetallic, internal-splined disk. It is splined to the

vanes and is deflected in the same direction as the

turbine hub and is located between piston assembly (11)

pump is rotating. Thus, the returning oil assists the

and lockup clutch back plate (15)

pump's rotation. This is the key to torque multiplication.

(4) Lockup clutch back plate (15, FO-3) is

a pressed steel ring, held between converter pump

2-1