TM 9-2330-294-14
reposition air control handle for load being trans-
fully by means of tiedown chains and by expedient
ported.
use of semitrailer deck curbing.
(2) `The air spring suspension of the semitrailer
2-21. Loading and
Unloading M747
Semitrailer
should be set to ensure loading on all axles to
Using Self-Powered Payload Vehicle
prevent overloading of any semitrailer axles (para 2-
a. Precautions.
19b (3)).
(1) Make sure towing vehicle and semitraile
(3) When raising or lowering the landing gear.
parking brakes are applied to assure maxim
use hand grip to control gear. The landing ramps
vehicle stability during drive-on/drive-off operation.
should be handled by two men (one man can handle)
(2) If on a grade, the downhill side of wheels
when raising or lowering the ramps. Exercise caution
should be blocked.
to avoid injury to personnel.
(3) Blocks should be used under the semitrailer
(4) When installing wheels, proper torquing
rear frame while loading payloads of 55 tons or
holes in both tandem wheels must be alined with
(4) A guide should stand on top of the
valve stems. When a wheel is installed in the field,
semitrailer gooseneck to assure constant visual
the wheel nuts must be tightened as much as
contact with payload driver.
possible using tire socket wrench ( 10, fig. B-2) and
(5) A ground guide should stand off the rear
corner of semitrailer and maintain visual contact
proper torque at the earliest opportunity at the
with guide on gooseneck.
organizational level. Failure to torque wheel nuts
(6) Prior to loading operations, a system of
properly will result in fatigue rupture of wheel studs.
signals to include "start", "stop, and "Slow down"
b. Highway Driving,
should be worked out between operator of towing
(1) Observe all towing vehicle operation in-
vehicle, operator of payload vehicle and all guides
structions, warnings and cautions.
(refer to FM 21-305).
(2) To prevent shifting of the payload vehicle,
curbing should be positioned on semitrailer deck,
weight and placement of curbing.
and the payload should be tied down front and rear.
b. Drive-On Loading.
Check and' tighten bindings at every rest and
WARNING
maintenance stop.
At no time during loading operations should
(3) Caution must be exercised during highway
personnel be on the semitrailer bed.
travel to ensure that all bridges and underpasses
WARNING
may be negotiated. Safety requirements, such as
Loading should not be conducted on side and
hazard flags, road permits, flashing warning lights,
lateral slopes exceeding 10 percent and with
and wide load signs, must be met,.
a tractor-to-semitrailer offset angle greater
(4) Operating air pressure to semitrailer brakes
then 5 degrees when using winch cables.
must be above 65 psi to prevent application of fail-
(1) Position semitrailer in line with payload on
safe units.
as level ground as possible. Set towing vehicle and
c. Short Trip Off-Road Driving.
semitrailer parking brakes.
(1) Paragraph b (1), (2), (3), and (4) above are
also pertinent to off-road driving.
(3) If two vehicles (M113 series and/or M114)
(2) Terrain and good judgment should dictate
are to be loaded, remove and stow two gooseneck
off-road speed. Always travel at a slower speed when
in doubt.
(4) When loading any firm-tracked vehicle such
d. Turning.
as crane or bulldozer, attach towing vehicle winch
(1) Avoid sharp left or right turns in excess of 10
cables to towing lugs of payload vehicle (B, fig. 2-17)
mph. Such turns may cause payload shifting and
as a safety precaution. Operate towing vehicle
overstressing of tiedown hardware with a resulting
winches to keep cable under even tension at all times
loss of vehicle control. Turns which may jeopardize
to prevent payload tipping or rolling backwards an
payload or vehicle stability should be limited to 10
to assist payload during breakover at top of ramp (C,
mph or less. Road conditions and good judgment
should dictate turning speed.
When loading a crane, turn crane counterbalance to
(2) When making sharp turns on narrow roads
forward end.
or on city streets, the semitrailer turning radius will
(5) Station guide on top of gooseneck to assure
be shortened by stopping semitrailer and positioning
constant visual contact with payload driver for
guiding, Station second guide off rear corner of
position to raise axles 7 and. 8. After making turn,