TM 5-3810-307-24-1-1
The torque converter consists of three basic
spring in the selector spool provides one position for
elements and their related parts which multiply
each speed range. A detent ball and spring in the
engine torque. The engine power is transmitted from
direction spool provides three positions, one each for
the engine flywheel to the impeller element through
forward, neutral, and reverse.
the impeller cover. This element is the pump portion
of the hydraulic torque converter, and is the primary
With the engine running and the directional control
component which starts the oil flowing to the other
lever in the neutral position, oil pressure from the
components to obtain the desired torque
regulating valve is blocked at the control valve, and
multiplication. The impeller can be compared to a
the transmission is in neutral. Movement of the
centrifugal pump in that it picks up fluid at its center
forward and reverse spool will direct oil under
and discharges at its outer diameter.
pressure, to either the forward or reverse direction
clutch as desired. When either directional clutch is
The torque converter turbine is mounted opposite the
selected, the opposite clutch is relieved of pressure
impeller and is connected to the output shaft of the
and vents back through the direction selector spool.
torque converter. This element receives fluid at its
The same procedure is used in the speed selector.
outer diameter and discharges at its center. Fluid
directed by the impeller out into the particular design
The direction or speed clutch assembly consists of a
of blading in the turbine and reaction member,
drum with internal splines and a bore to receive a
provides the coupling by which the hydraulic torque
hydraulically actuated piston. Sealing rings make
converter multiplies torque.
the piston oil tight. A steel disc with external splines
is inserted into the drum and rests against the piston.
The reaction member of the torque converter is
Next a friction disc with splines at the inner diameter
located between and at the center of inner diameters
is inserted. Discs are alternated until the required
of the impeller and turbine elements. Its function is
total is achieved. A heavy back-up plate is then
to capture the fluid which is exhausting from the
inserted and secured with a snap ring. A hub with
inner portion of the turbine and change its direction
OD splines is inserted into the splines of discs with
to allow correct entry for recirculation into the
teeth on the inner diameter. The discs and hub are
impeller element.
free to increase in speed, or rotate in the opposite
direction as long as no pressure is present in that
The torque converter will multiply engine torque to its
specific clutch.
designed maximum multiplication ratio when the
output shaft is at zero rpm. Therefore, as the output
To engage the clutch, the control valve is placed in
shaft is decreasing in speed, the torque multiplication
the desired position. This allows oil under pressure
is increasing.
to flow from the control valve, through a tube, to a
chosen clutch shaft.
This shaft has a drilled
The torque converter is equipped with automatic
passageway for oil under pressure to enter the shaft.
lockup capabilities. This feature allows the torque
Pressure sealing rings located on the clutch shaft,
converter to change from a fluid coupling to a direct
direct oil under pressure to the desired clutch.
mechanical link between the engine and
Pressure of the oil forces the piston and discs
transmission at a predetermined rpm level. The
against the heavy back-up plate. The discs, with
lockup function is controlled by the lockup solenoid
teeth on the outer diameter, clamping against discs
located on the right wall of the transmission well.
with teeth on the inner diameter, cause the hub and
Torque converter slippage is eliminated when in the
clutch shaft to be locked together and force them to
lockup mode, allowing the engine to run at a lower
drive as a unit.
rpm to maintain vehicle speed. It also provides the
advantage of using engine compression as a brake
There are bleed balls in the clutch piston which allow
in downgrade conditions.
quick escape for oil when the pressure to the piston
is released.
The shift control valve assembly consists of a valve
body with selector valve spools. A detent ball and
2-3-8
