Hudson 1947 3/4-TON COMMERCIAL, Owner'S Manual

Page: 51 / 75

TRANSMISSION OVERDRIVE
(Optional Equipment)
Transmission Overdrive, Fig. 38, is available on all models as a factory installed
option only. It is not available for field installation. This unit provides a fourth speed
operation at approximately 22 miles per hour and also permits free wheeling on
deceleration below about 19 miles per hour. It reduces engine speed 28 per cent in
relation to car speed, thus permitting smoothness of operation and greater gasoline
and oil economy at high speeds.
The speeds at which overdrive becomes operative on acceleration and when free
wheeling becomes effective on deceleration, are controlled by a centrifugal governor
switch mounted on the overdrive housing. Engagement and disengagement of Over-
drive is controlled through the accelerator pedal when the Overdrive control knob,
located on the instrument panel, is pushed in. Conventional operation is obtained
when the knob is pulled out.
OPERATION—Push the control knob, on the instrument panel, in to its fullest
extent. This may be done at any speed. At speeds of approximately 22 miles per
hour, by releasing the accelerator pedal momentarily the shift into Overdrive is
accomplished automatically. Then depress the accelerator for normal operation in
Overdrive. The car will now remain in Overdrive until its speed has been reduced to
about 19 miles per hour at which time Overdrive will automatically disengage and
the car will drive through free wheeling.
As operation in Overdrive does not permit fast acceleration for passing other cars
or provide the necessary power to ascend steep grades it is necessary to revert
temporarily to direct drive. This can be accomplished by depressing the accelerator
pedal fully beyond the wide-open throttle position. As this action takes place the
ignition is interrupted for a fraction of a second, releasing the Overdrive and permit-
ting the engine to pick up the load in direct drive through the free wheeling unit.
To re-engage Overdrive, momentarily release the accelerator pedal as before
(above about 22 miles per hour) and then resume normal operation in Overdrive.
If it is desired to lock out Overdrive when operating in heavy traffic, or on icy or
slippery pavements, or steep grades, when free wheeling is not desired, it is merely
necessary to pull out the control knob and disengage the clutch momentarily. This
must be done when the car is in motion and may be done at speeds up to 60 miles per
hour. A slight clash may be noted at this time. See Page 47 for lubrication data.
HUDSON OWNER’S MANUAL 49