Operation and maintenance manual

Section 120-0010
Transmission - Transmission and Mounting
SM 2124 Rev 3 8-03
8
The electronic control system distinguishes between
the throttle position (or load ranges) depending on the
governor position (injection pump). On a light throttle
opening, the transmission will give earlier upshifts
and later downshifts than when operating at full
throttle.
A kickdown facility (See Fig. 6), which can be used
when automatic mode is selected, allows for the
possibility of selecting a lower gear by pressing down
fully on the throttle pedal and holding. This can be
used to provide a downshift on demand provided that
the vehicle speed is within the range allowable. That
is, the vehicle is not travelling at a speed that would
result in the engine overspeeding in the lower gear.
When driving with kickdown, the transmission will
give earlier downshifts and later upshifts. To
disengage the transmission kickdown, release the
throttle pedal and allow it to return to a light throttle
position.
When operating in automatic range with the display
indicating that the transmission has downshifted to
2nd gear, there are two options for providing a further
downshift as conditions indicate.
1. 1st gear can be manually selected by pushing the
shift lever to the left.
2. Kickdown can be selected from 2nd automatic,
when the transmission will downshift to 1st gear,
depending upon vehicle speed.
When the kickdown is released the transmission will
upshift to 2nd automatic, provided that the forward
speed has increased sufficiently to allow this to
happen, and that the shift lever is in the automatic
mode.
A dashboard display is provided which indicates gear
selected and driving direction as follows (See Fig. 7):
Manual Mode - When driving with shift selector in
manual range, the bars only are shown in position 1,
and, driving direction and gear selected are indicated
in positions 2 and 3.
Automatic Mode - When driving with shift selector in
automatic range, a full display of bars and arrows are
shown in position 1, and, driving direction and gear
selected are indicated in positions 2 and 3.
Under certain conditions the transmission may start
to 'hunt' between gears when in automatic mode. The
transmission changes up and down between two
gears at short intervals because there is not
sufficient power to sustain driving in the higher gear,
but is sufficient for upshifting from the lower gear. By
using the shift display, it can be established which
gears are involved and in these circumstances the
lower gear should be selected using the shift control
lever. Automatic mode should be reselected at the
earliest opportunity.
During machine operation, watch for wide deviations
from normal readings on the transmission oil
temperature gauge. If the gauge shows the oil
temperature rising above the green zone during
normal operation, or above the yellow zone during
retarder operation, the machine must be stopped and
inspected for external oil leakage. If no leaks are
found, shift to 'NEUTRAL' and operate the engine at
1 200 - 1 500 rev/min. If the transmission oil
temperature does not decrease into the green zone
within 2 or 3 minutes, the cause of the overheating
should be corrected before the machine is operated
further.
Fig. 6 - Accelerator Load Ranges and Kickdown Position
SM - 1828
Fig. 7 - Dashboard Display
SM - 2335
1 - Bars show gear ranges and full display (as
shown) indicates driving in automatic mode.
2 - Display shows actual driving direction.
3 - Display shows actual gear in use.
IDLE
FULL LOAD/
THROTTLE
KICK/HOLD
DOWN
S
T
O
P
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