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PART 7-1
AUTOMATIC TRANSMISSION (Borg-Warner)
7-5
INNER
GEAR
@
INLET
Q)
OUTLET
-
@
SUCTION
-
®
LINE PRESSURE
FIG. 5 -Oil Pump Operation
Downshift Valve and Throttle
Valve.
The down shift valve
,
connected
to the throttle linkage by a cable
actuated cam, varies control pres-
sure with accelerator pedal de-
pression
.
Movement of the down-
shift valve compresses the throttle
valve spring located between the
downshift valve and the throttle
valve
.
This spring is opposed by
the throttle return S!)ring combined
with throttle pressure, acting at
low car speed
,
on one area of the
throttle valve
,
and at high road
speed on two areas of the throttle
valve
.
A pressure is produced
therefore, proportional to both en-
gine load and car speed
.
Th1s pres-
sure is directed to the primary regu-
lator valve spring end to vary basic
control pressure accordingly
,
so
providing correct servo and clutch
capacities and consistent change
quality under operating
conditions.
Full movement of the downshift
valve directs throttl
e
pressure to
the shift valves to delay changes
up, or effect third
to
second or
third to first changes at pre-set
maximum
speeds.
Also
,
throttle
pressure is directed to the second
to third valve plunger.
This re-
duces the value of throttle pressure
by a fixed amount and this pressure
is diFeeted to the first to second
WEIGHT
VALVE
GOVERNOR
SPRING
•
VEHICLE STATIONARY
FIG. 6 -Governor Operation
LOW SPEED OPERATION
and second to third valves to con-
trol the change points sensitivity
relative to throttle pressure and
,
therefore
,
accelerator position
.
The modulator plunger is a re-
gulating valve that reduces throttle
pressure by a fixed amount.
This
modulated pressure operating on
one end of the plunger assisted by
the modulator valve spring, is op-
posed by throttle pressure operating
on the opposite end of the valve
.
This modulated throttle pressure is
directed to the primary regulator
valve thus varying the increase
rate of control pressure relative to
throttle pressure
.
The modulator valve is a shuttle
valve
.
Governor pressure oper-
ating on the large end is opposed
by the modulator
spring.
As gov-
ernor pressure rises with road speed
the valve moves. contacting the
modulator plunger.
Further vaJv,
:
movement prevents the plunger
from regulating, and modulated
throttle
pressure
then
becomes
equal to throttle
pressure.
This
movement directs throttle pressure
to a second area of the throttle
valve and by this means the high
throttle and control pressures exist-
ing at the converter stall condition
are reduced when the car is moving
for satisfactory gear change quali-
ties.
Servo Orifice Control Valve.
This is a shuttle valve in the
front servo release circuit with
governor pressure acting on the
valve opposed by the servo orifice
control valve spring.
At low gov-
•
HIGH SPEED OPERATION
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