Subaru 1600 Service Manual page 311

AUTOMATIC TRANSMISSION AND DIFFERENTIAL
Fig. 7·17
• Operation of each component
Shoe ... The shoe rotates at the same
speed as the torque converter turbine,
and slides along the inner circumfer-
ence of the turbine cover. The shoe
sometimes becomes completely en-
gaged with the turbine cover, however,
it usually slides in a half-clutch condi-
tion. The engine torque is transmitted
from the turbine cover through the
shoe to the reaction plate and then to
the output shaft. Paper is used for the
facing.
Weight ... Using the centrifugal force
produced by the rotation of the
weight, the clutch transmits torque.
The weight's primary purpose is to
increase the transfer torque capacity
in the medium- and low-speed ranges.
Main spring '" The centrifugal force
acting on the weight is transmitted to
the shoe through the main spring. In
the medium- and low-speed ranges, the
load of the spring increases in propor-
tion to the centrifugal force of the
weight, so that torque capacity also
increases. In the medium- and high-
speed ranges, however, the spring load
becomes constant regardless of the
centrifugal force of the weight, func-
tioning as a torque limiter.
Retractor spring '" This spring always
functions to pull the shoe inward,
which, in the low-speed range where
the centrifugal force is small, prevents
the shoe from touching the drum.
Pin ... The pin fixes the shoe in place
so that it will not come off the
reaction plate, and also serves as the
weight stopper.
CD
@ @ @
2. Operation
1) First range (low-speed, non-
operating range)
Because the return force of the re-
tractor spring is greater than the
centrifugal force acting on the shoe
and weight, the shoe is drawn inward
and kept away from the drum. Thus,
torque is not transmitted through the
shoe.
As the revolution increases and when
the centrifugal force becomes greater
than the return force of the spring, the
shoe contacts the drum and begins to
transfer torque (lower figure).
A13·415
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A13-416
Fig. 7-18
2) Second range (medium- and low-
speed range, centrifugal clutch range)
The centrifugal force of the weight
deflects the main spring, and the
weight floats up off the concavity at
each end of the shoe (portion
@
in
Fig. 7-19).
Although a portion of the weight's
centrifugal force is transmitted from
the retractor spring to the pin, the
7-16
1 Shoe
2 Main
spring
3 Retractor spring
4 Weight
5 Pin
A13-414
greater part of it pushes the shoe
through the main spring, working as
the power that transmits torque.
On the other hand, the centrifugal
force acting on the shoe itself becomes
the force that pushes the drum regard-
less of the movements of the weight.
Therefore, the press of the shoe neces-
sary to transmit torque in this range
becomes: Shoe's centrifugal force
+
(Weight's centrifugal force - Retractor
spring's return force).
When the speed of rotation goes still
higher, the centrifugal force of the
weight increases further, and the main
spring deflects more, both ends of the
weight butt against the pins (through
the retractor spring), so that the
weight will not move toward the
circumference.
Fig. 7-19
3) Third range (medium- and high-
speed ranges, torque limiter range)
Because the speed of rotation is high,
the weight is stopped, completely
pressed against the pins at both ends.
The centrifugal force acting on the
weight at this time is carried directly
from the weight to the pins and then
to the reaction plate, and therefore it
is not transmitted to the shoe. Accord-
ingly, in this range the transfer torque
of the clutch is the frictional force
produced by the centrifugal force of
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