1956 AMC Hudson Technical Service Manual Supplement

28 TECHNICAL SERVICE MANUAL
it up for maximum output. When pressure becomes high, the
pressure regulator valve is forced outward, directing oil
pressure above the slide to push it down and decrease the
output.
When the slide is up, it delivers maximum output. When
the slide is centered, output is zero.
The torus check valve is held against the pump slide by
spring pressure. When the slide moves down, oil will pass
through the torus check valve and into the cooler passage
from the cooler to the torus feed passage. If the cooler should
become inoperative, oil from the torus check valve will
unseat a ball check held in position by spring pressure and
flow into the torus feed passage.
REAR PUMP
The rear pump is of the fixed displacement gear type and is
driven by the output shaft; therefore, rear pump capacity will
vary with car speed. At idle, the rear pump is not supplying
oil to the transmission and all oil pressure will be supplied
by the front pump.
As the speed of the car increases, the oil from the rear
pump will flow together with the front pump oil through a
passage in the case. Much of the oil pressure requirements
of the transmission will be taken over by the rear pump and
the front pump will compensate by reducing its output.
The basic requirements of a need for a rear pump was the
necessity for oil pressure to supply the transmission in the
event of a need for a push to start the vehicle.
ACCUMULATOR
To effect a smooth apply of the rear clutch, 2-3 oil being
directed to the rear clutch apply piston is also directed to an
accumulator. The accumulator contains a piston with heavy
springs holding the piston in the down position which is
opposing 2-3 oil directed to the other side of the piston. Oil
from the 2-3 shift valve will move the accumulator piston
against spring and oil pressure and also apply the rear clutch.
Since the flow of oil to the accumulator and clutch apply
piston is restricted, the accumulator is capable of collecting
any oil that does flow through the restriction at the pressure
valve which is required to move it. This maintains the
pressure acting on the clutch piston, at a value below line
pressure, until the accumulator is full. At that time, the
pressure rises to line pressure. The engagement of the clutch
must be completed before the accumulator is full to produce
smooth shifts at the lower apply pressures.
Clutch apply requirements will vary with throttle and load
conditions. The accumulator is a factor in rear clutch engagement;
its operation is varied accordingly by directing
T.V. pressure to assist the spring in resisting 2-3 oil pressure.
This T.V. pressure to the accumulator is regulated by a
trimmer valve located in the accumulator body, held in the
open position by spring and closed by T.V. pressure, thereby
regulating T.V. pressure to the accumulator as the need
requires.
LOW SERVO
The low servo located in the accumulator body is used to
apply the low range band when the selector lever is moved
to the "L" range position. Oil is directed from the manual
valve to the servo to apply the low range band which holds
the rear unit internal gear and prevents the vehicle from
overrunning the rear sprag clutch when "L" range is being
used for engine braking.
HOW TO OPERATE THE FLASHAWAY HYDRA-MATIC
The Flashaway Hydra-Matic drive is convenient to operate
by placing the selector lever in the desired speed range.
These positions are shown on the indicator which is illuminated
when the instrument lights are on (Fig. 2).
The speed range positions are designated as follows:
P —Parking and starting
N —Neutral and starting
D-4—For all normal forward driving
D-3—For faster acceleration and driving in congested t
raffic
L —For controlled power
R —For reverse
NOTE: Selector lever must be raised to engage
parking and reverse position.
ENGINE STARTING
FIGURE 2—Selector Lever Indicator
The safety starter switch is mounted on the starter switch