UPSHIFTING (NORMAL HIGHWAY) DOWNSHIFTING (NORMAL HIGHWAY) To begin, position the shift lever in neutral and select Lo split using the splitter selector. Then select Lo range using the range selector. Shift from eighth (Hi range, Hi split) to eighth (Hi range, Lo split), then to seventh (Hi range, Hi split) to seventh (Hi range, Lo split) and so on, double-clutching between each gear until fifth (Hi range, Lo split) is reached. Move the shift lever to the Lo-speed gear (Lo range, Lo split) position. Apply the accelerator, engage the clutch and accelerate to governed speed. Select Hi with the splitter selector and release the accelerator.
Wait for the split shift to complete and then reapply the accelerator. Shift up through first (Lo range, Lo split), first (Lo range, Hi split), second (Lo range, Lo split), second (Lo range, Hi split) and so on, until fourth (Lo range, Hi split) is reached. Double-clutch between the gears. While in fifth (Hi range, Lo split), move the range selector to Lo (preselect), select Hi on the splitter selector (preselect) and then move the gear shift to fourth (Lo range, Hi split). As the gear shift lever passes through neutral, the range shift to Lo and the split shift to Hi is completed.
Then, continue using the shift lever and splitter selector as described to shift down to Lo (Lo range, Lo split). Continue shifting while in fourth gear (Lo range, Hi split), move the range selector to Hi (preselect), select Lo on the splitter selector (preselect) and then move the gear shift to fifth (Hi range, Lo split). As the gear shift lever passes through neutral, the range shift to Hi and the split shift to Lo is completed. To continue, use a combination of splitter selector and shift lever to shift to fifth (Hi range, Hi split), sixth (Hi range, Lo split), sixth (Hi range, Hi split) and so on, until eighth (Hi range, Hi split) is achieved.
To downshift from Hi split to Lo split (in same gear position), as engine speed falls, preselect Lo split, release the accelerator and reapply it (audible shift should be heard). To downshift from Lo split in one gear to the next gear Hi split, move the shift lever into neutral, select Hi split, and move the shift lever to the next lower gear. Be careful not to overspeed the engine during downshifting. Damage to powertrain components may result. To upshift from Lo split to Hi split (in the same gear), accelerate the engine to governed speed, move the splitter switch to Hi (preselect), then depress the clutch and back off the accelerator pedal.
Reapply the accelerator and engage the clutch when the audible shift is heard, or when the engine speed falls by approximately 200 rpm. Depressing the clutch may not be necessary to break the driveline torque, but this will vary with road conditions. To avoid transmission damage, do NOT change range while moving in reverse gear. Make sure air pressure is at least 100 psi and unit is warmed before making range shifts. Always start in Lo range per shift marker plate instructions. Never start higher than second (Lo range, Lo split) gear, including when dynamometer testing.
To upshift from a Hi-split gear to the next higher gear's Lo split (in Hi-range), accelerate the engine to governed speed, break the driveline torque by depressing the clutch or backing off the accelerator pedal, then move the splitter switch to Lo and, at the same time, move shift lever through neutral to the next higher gear. Note that the splitter switch must not be actuated down to the Lo position until the main box is in neutral. With truck stationary, do not shift into Hi range and then move the truck. Damage to the synchronizer can result. Page 25 DESCRIPTION AND OPERATION