SRT55D Off-Highway Truck
3-28
Safety, Operation and Maintenance Manual
Controls and Operating
the rear of the vehicle. This feature warns
personnel to the immediate rear of the vehicle
that the operator has shifted to reverse.
When drive 'D' is selected, the transmission
automatically upshifts and downshifts through
all six forward ranges as required by loads and
travel speeds. Selecting a lower range (4th,
3rd etc.) limits the highest range to which the
transmission will automatically upshift.
If a lower range is selected while moving
forward, the transmission automatically
downshifts sequential to the selected lower
range at maximum controlled engine speeds.
Downshifts will not occur until vehicle is
slowed by use of the service brakes and/or
retarder.
When shifting from neutral to start from a
standstill, or to reverse direction, decelerate
the engine to idle speed. To move forward,
select drive 'D' and accelerate the engine to
the vehicle load and speed requirements. The
transmission will automatically upshift from 1st
through 5th ranges as travel speed increases.
With the throttle fully depressed, and the
mode selection switch in the Power position,
the transmission upshifts to the next higher
range when the engine attains maximum
rated speed, since maximum power train
output is needed under this condition. At lower
throttle settings where minimum power train
performance is required, the transmission will
upshift to the next higher range at less than
maximum rated engine speed.
Upgrades or soft spots might slow travel
sp e e d, e ven at fu l l t h r ott l e, r equ i r ing
transmission downshifts to maintain maximum
powertrain performance. When this occurs,
the transmission downshifts automatically.
Shift the transmission to the next lowest range
if transmission 'Hunting' or 'Shift Cycling'
occurs.
When temporarily stopped, such as for
yielding the right-of-way to a loaded vehicle,
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