Ford F-650 Owner's Manual page 145

To shift the axle from LOW to HIGH with the vehicle moving, accelerate
to approximately 35 mph (56 km/h), press the lower part of the switch
while the transmission is in N (Neutral), then release and apply the
accelerator.
To shift the axle from HIGH to LOW with the vehicle stopped, place the
transmission in N (Neutral), then press the upper part of the switch.
Note: Do not shift the axle to LOW with the vehicle in motion.
Split-shifting (combined axle and transmission shift - manual
transmissions only)
Ratio combination 1
Transmission gear 1st 1st 2nd 2nd 3rd 3rd 4th 4th 5th 6th 6th
Axle range LO HI
To downshift the axle to a slower ratio and shift the transmission, shift
the transmission and move the switch to the lower ratio before the
clutch is re-engaged.
To upshift the axle and shift the transmission, move the switch to a
faster ratio and make the transmission shift in the usual manner.
Ratio extender use
Low end: A two-speed axle can be used as a ratio-extender when
split-shifting is not necessary. For low end use, just shift the axle into
LOW to start out, and shift to HIGH when the extra torque is no longer
needed.
Transmission (5-speed)
Two-speed axle
High end: To use the two-speed axle as a high end ratio-extender, stay
in the LOW range for normal upshifts and only shift the axle to HIGH on
the freeway for greater road speed.
Transmission (5-speed)
Two-speed axle
2012 F-650/750 (f67)
Supplement, 2nd Printing
USA (fus)
Split-shift sequence
2 3 4 5 6
LO HI LO HI
1st 1st 2nd 3rd 4th 5th 6th
Axle low
1st 2nd 3rd 4th 5th
Low for gradeability
Driving
7 8 9 10 11
LO HI LO LO HI
Axle high
6th
Axle high
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