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Gear Down Protection Turn On Speed
Engine
Range
Cat
DefaultMinimum Maximum
3126E, C7, C9 (Other)
C-10, C-12, C-15, C-16,
C11, C13, C15
30 MPH
(48 km/h)
127 MPH
(204 km/h)
127 MPH
(204 km/h)
3126E, C7, C9 (GM)
30 MPH
(48 km/h)
75 MPH
(121 km/h)
75 MPH
(121 km/h)
EPA’07 and newer
C7, C9, C13, C15
30 MPH
(48 km/h)
127 MPH
(204 km/h)
75 MPH
(121 km/h)
Advantages:
Gear Down Protection helps ensure that the truck is run
in the correct (highest possible) gear at cruising speed.
Properly setting these parameters will keep the engine
in the most fuel effi cient rpm range to achieve the best
fuel economy at cruising speed.
Disadvantages (possible):
Some driveline combination can allow a driver to reach
cruising speed in more than one gear even with this
feature properly set. However, gear down protection is
still moderately effective in these situations and should
be used.
If the Gear Down Protection RPM Limit is set too low,
the driver may have to wait too long to downshift when
climbing steep grades with heavy loads. This may cause
the driver to drop two transmission gears, when one
would have been adequate.
Recommendations:
✔ Set the Gear Down Protection RPM Limit such that
highway cruising speeds can only be reached in
top gear (Use Cat
®
Design Pro).
✔ Set Gear Down Protection RPM Limit high enough
that engine rpm does not drop below peak torque
plus 100 rpm during upshift.
✔ Set the Gear Down Protection Turn On Speed well
below the cruise speed. As with all electronic shift
strategies, do not set “gear-on” speeds on top of
shift points.
Engine/Gear Parameters