CHAPTER 2. DESCRIPTION AND OPERATION

CHAPTER 2

D E S C R I P T I O N AND OPERATION

Section I. DESCRIPTION AND OPERATION OF TRANSMISSION COMPONENTS

2-1. Torque Converter and Lockup Clutch

clutch is released, the torque converter must

transmit engine power to the transmission. When

a. Torque Converter Components (fig. 2-1).

the lockup clutch is engaged, there is no converter

(1) The torque converter consists mainly of

action and torque is transmitted directly from

three cast aluminum elements: a converter pump

engine to transmission because the input drive

(8), converter turbine (6), and a stator and cam

components and converter turbine (6) are locked

assembly (7). In addition, there are other parts in

together.

the group which house and support these main

(2) When the lockup clutch is released, the

elements.

torque converter (which is constantly filled with oil)

(2) The converter pump assembly (8) is the

transmits torque by hydraulic action. The blades of

driving element. It rotates on a ball bearing

the pump (8) throw oil against the blades of the

assembly (9) supported by a converter ground

turbine (6), causing the turbine to rotate in the

sleeve (10) which is stationary and a component of

same direction as the pump. Higher pump speeds

the diaphragm assembly (12). The pump is bolted

cause the oil to be thrown with more force, causing

to a cover assembly (4) which rotates with the

a greater rotating force in the turbine. At engine

engine crankshaft.

idle speed, the force of the oil, and consequently the

(3) The converter turbine assembly (6) is the

torque transmitted, is negligible. This characteristic

driven element. It is splined to a turbine shaft (59)

of hydraulic drive permits the torque converter to

which transmits torque to a high-range clutch

housing (16), intermediate-range sun gear (53),

take the place of a friction clutch between the

engine and transmission.

and a low-range sun gear (46). The turbine hub (2)

(3) The turbine vanes direct the oil toward the

is splined to a lockup clutch plate (5).

center of the turbine (6), where the oil leaves the

(4) The stator and cam assembly (7) is the

turbine in a direction opposite to pump rotation.

reaction element. It is mounted on an over-running

The stator (7) redirects the flow of oil to change its

clutch on a freewheel roller race (63) which is

direction to that of pump rotation. Unexpended

splined to a ground sleeve (10). The stator is free to

energy in the oil reentering the pump (8) assists the

rotate in the direction of engine rotation but locks

pump. This is the key to torque multiplication.

up in the opposite direction.

b. lockup Clutch Components (fig. 2-1).

(4) Thus, the torque converter is a torque

multiplier as well as a fluid coupling. Torque

(1) The lockup clutch piston assembly (64) is

multiplication is highest when the turbine (6) is

a spring steel diaphragm with a clutch apply plate

stalled and the pump (8) is rotating at full speed. It

at its outer circumference. It is mounted on the

is lowest when the pump is rotating at its lowest

inner hub of the converter pump cover assembly

speed relative to the turbine.

(4). and retained by a snap ring. Recesses in the

(5) The oil, leaving the inner ends of the

piston engage the heads of the converter drive bolts,

turbine vanes, strikes the curved vanes of the stator

and prevent rotation of the piston relative to the

and is deflected into the pump vanes. It is the

pump cover.

reaction of the oil, as it is forced to change direc-

(2) The lockup clutch plate (5) is a non-

tion, which locks the stator against rotation op-

metallic, internal-splined plate. It is splined to the

posite to pump and turbine rotation. When turbine

converter turbine hub and located between the

piston (64) and the lockup clutch back plate (62).

speed approaches pump speed, the oil leaving the

turbine strikes the back sides of the turbine vanes

(3) The lockup clutch back plate (62) is a

and causes the stator to freewheel on the rollers

pressed steel ring against which the plate (5) reacts

(61).

when the lockup clutch is applied. Its outer

(6) When torque multiplication is no longer

diameter is held between the converter pump cover

required to provide sufficient power to the vehicle

(4) and tbe pump (8) which are bolted together.

drive line and vehicle speed is great enough, the

c. operation of Torque Converter and Lockup

lockup clutch automatically engages. In lockup

Clutch (fig. 2-1).

operation there is no hydraulic slippage. The result

(1) The actions of the torque converter and

is economy in operation and improvement in

lockup clutch are interrelated. When the lockup

operating characteristics.

2-1