228 OPERATION
MACK T31821, T318L21 and T318LR21 Shifting
Instructions
CAUTION
Make sure air pressure is at least 90 psi and unit is at operating temperature before
making range shifts. Always start in LO range. This also applies to dynamometer
testing. When the truck is stationary, do NOT shift into HI range and then start
moving the truck. Otherwise, damage to the synchronizer may result.
Note:
When making a SPLIT SHIFT from gear to gear, the splitter switch must not
be actuated, either up or down, until the main box is in NEUTRAL. When making
a SPLIT SHIFT in the same gear to a preselected gear, especially under a heavy
load, the splitter will not shift until the driveline torque is relieved. This can be done
by depressing the clutch pedal and releasing it, or by backing off the throttle and
reapplying it. The splitter switch must not be actuated, either up or down, until
IMMEDIATELY before the driveline torque is relieved. When making a RANGE
SHIFT, it is important to preselect the range shift. This means that the range selector
must be moved to its next position (up or down) BEFORE the gearshift lever is
moved. Then move the gearshift lever through NEUTRAL to the next desired gear
position. As the lever passes through NEUTRAL, the range shift will be completed.
Upshift —
For purposes of explaining the shifting procedures through ALL
gears, assume that the vehicle has a full load and will climb a slight grade.
To prepare for moving the vehicle, position the shift lever in NEUTRAL, select
LO-split using the splitter switch, and select LO range using the range selector.
Refer to the shift pattern and move the shift lever to LO speed gear (LO
range, LO-split). Apply accelerator and engage the clutch, then accelerate
to governed speed. Select HI on the splitter switch (preselect) and release
the accelerator pedal long enough for the split shift to complete. Reapply the
accelerator. Shift through first LO-split, first HI-split, second LO-split, second
HI-split and so on, until you reach fourth HI-split. Remember to double-clutch
between gears.
To continue while in fourth gear HI-split, flip the range selector up to HI range
(preselect), and as you move the shift lever through NEUTRAL to fifth gear,
move the splitter switch from HI to LO. As the lever moves through NEUTRAL,
the range shift to HI will be completed. You are now in fifth gear LO-split (HI
range). Continue shifting to fifth HI-split, sixth LO-split, sixth HI-split and so
on, until you reach eighth HI-split. Remember to double-clutch between gears.
Summary of Contents for Granite GU Series
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Page 44: ...SAFETY INFORMATION 33 Advisory Label Locations On Vehicle Labels Found on Chassis C0029831 ...
Page 45: ...34 SAFETY INFORMATION C0028958 ...
Page 46: ...SAFETY INFORMATION 35 C0028959 ...
Page 47: ...36 SAFETY INFORMATION C0029013 1 Right Side Frame Rail 2 Hood Prop ...
Page 48: ...SAFETY INFORMATION 37 C0029014 ...
Page 49: ...38 SAFETY INFORMATION Labels Found on Driver Side Sun Visor C0029832 ...
Page 50: ...SAFETY INFORMATION 39 C0029016 ...
Page 58: ...SAFETY INFORMATION 47 C0029833 ...
Page 60: ...SAFETY INFORMATION 49 C0029834 ...
Page 62: ...SAFETY INFORMATION 51 C0029835 ...
Page 72: ...INSTRUMENTS AND CONTROLS 61 Panel B W3056238 ...
Page 81: ...70 INSTRUMENTS AND CONTROLS C0029141 ...
Page 82: ...INSTRUMENTS AND CONTROLS 71 Diagnostics W3036575 W3036576 W3036583 ...
Page 84: ...INSTRUMENTS AND CONTROLS 73 C0029144 ...
Page 113: ...102 INSTRUMENTS AND CONTROLS C0029240 C0029241 ...
Page 235: ...224 OPERATION C0029351 ...
Page 241: ...230 OPERATION C0029352 ...
Page 284: ...MAINTENANCE AND LUBRICATION 273 C0029851 C0029852 1 Towhook Access ...
Page 305: ...294 MAINTENANCE AND LUBRICATION C0029434 1 Front 2 Back ...
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