front steer only). When moving the steering selector
control back to front wheel steer position, the rear wheels
The air brake system is so designed that an automatic
brake application is made when the service reservoir
will center automatically. The crab position of the
pressure falls below 40 psi. If the emergency pressure
steering selector control allows both front and rear
should drop below 60 psi, the emergency-park situation
wheels to be turned in the same direction, allowing the
This same situation can be
machine to be moved at an angle, sideways, or precise
produced by actuating the emergency-park brake control
positioning. Moving the steering selector control back to
manually. A brake application may also occur on a vehicle
front wheel steer will automatically center the rear
being towed. Be sure the towing vehicles air brake
wheels. The front wheel steer position of the steering
pressure has sufficient pressure and capacity (120 psi) to
selector control provides conventional front wheel
release the emergency-park brake before attempting
steering for normal operation. A manual steering lock is
provided for the rear axle and should be installed for
over-the-road travel (fig. 2-12).
Do not attempt to move the equipment until the air
(5) If the terrain to be traveled is very rough, it
pressure gage indicates sufficient air pressure (120
may be desirable to operate the carrier in fourwheel
psi) to operate the brakes. Partial release of the
drive. To engage the front wheel drive, stop the vehicle
emergency brake will generate heat and could cause
and pull the front axle declutch control (fig. 2-16, (43))
tire and axle failure.
back, to engage the front axle drive.
(3) If the utility blade is down, pull the utility blade
control lever (37) up, and lock the blade by pulling up on
Do not engage the front axle drive with the vehicle in
the utility blade lock control (36) and turning 1/4 turn
(6) Position the transmission gear range selector
(4) Position the front axle declutch control (9) in
control (38), in number one position and accelerate the
the two-wheel drive position by pushing the control lever
carrier slowly. Shift the transmission to the desired
speed range one position at a time.
The crane carrier should not be operated in four wheel
Do not skip shift the transmission.
drive at high speeds, over the road. The front axle may be
engaged for mud, snow, or on ice or rough terrain to
(1) Use a vehicle with an air brake system
afford more traction.
capable of producing 120 psi air in the system.
(5) Position the transmission gear range selector
(2) Use medium tank tow-bar, "V" type, 8-1/2
control (38) in number one position and depress the foot
feet long, heavy duty, FSN 4910-378-2012 for towing.
throttle slowly. Shift the transmission through all four
(3) If possible, place the boom over the front
gear ratios. Do not skip shift the transmission.
which is the most stable position for towing.
(4) If towing is to be for more than /4 mile or at
The lockup position of the transmission gear range
speeds in excess of 5 miles per hour, disconnect the
selector control (38) provides a means to lockup the
propeller shafts from the front and rear axles as shown in
torque converter in order to eliminate slippage in the
converter while in 3rd and 4th speed range only. Do not
(5) Install the rear wheel steer lock.
attempt to down-shift transmission going down grades.
(6) Install the utility blade brace as illustrated in
Do not use the converter lockup feature (in 3rd and 4th
speed range) during off the road travel.
Operating the Crane Carrier Over Rough
(7) Connect the tow-bar and jumper air hoses as
(2) Raise the utility blade and lock in TRAVEL
Ensure that air hoses are connected to the correct
connection, which is "Emergency" on carrier to
"Emergency" on prime mover and "Service" on carrier to
(3) Release parking brake control as described
"Service" on primer mover.
(8) Place the tractor protection brake control
(4) The carrier is equipped with a three-position
valve (17, fig. 2-16) to the EMERGENCY position: raise
steering selector control (fig. 2-16, (45)) which can be
air pressure in carrier to 120 psi, and release brakes as
used to place the crane carrier in a precise position.
directed in a above.
Placing the steering selector control in fourwheel steer
position provides steering on both front and back wheels,
(1) Install the utility blade brace as illustrated in
allowing a reduced turning radius (but only in 1st and 2nd
speed ranges). (If shifted to 3rd or 4th gear range, the
steering selector will automatically return to neutral or