Four-Wheel (4WD) Drive Operation. If more traction is required due to slipping or
spinning wheels, engage the rear axle drive. Engage 4WD as follows:
Position the DRIVE AXLE Selector Switch (37, Figure 5-2) to the 4WD
Crane must be traveling at a speed below 11 mph
(18 kph) for 4WD to engage and remain engaged.
Return the DRIVE AXLE Selector Switch (37) to the 2WD position as soon
as 2WD traction will suffice.
Inter-axle Differential. To lock out the inter-axle differential (front and rear, or just
rear differentials) and achieve maximum pulling power when approaching slippery or poor road
conditions, proceed as follows:
The differential lock can only be engaged when 4WD
is active. Do not actuate the DIFFERENTIAL LOCK
slipping or spinning.
Position DIFFERENTIAL LOCK Switch (31) to FRONT & REAR LOCKED
position to lock the front and rear differentials or the REAR LOCKED position
to lock the rear differential, while maintaining crane speed [below 11 mph
Let up momentarily on accelerator. This will engage the differential lock.
Use extreme caution when driving over poor roads.
As soon as driving conditions improve, perform the following:
Position DIFFERENTIAL LOCK Switch (31) to the UNLOCKED (center)
position while maintaining crane speed.
Let up momentarily on accelerator to allow the shift.
Resume driving at a safe speed.