TM 9-2330-294-14
(d ) Repeat procedures (a ) through (c ) above
d. Securing Payload Vehicle. Refer to paragraph
until vehicle is unloaded from semitrailer.
2-22 for payload tiedown procedures.
(9) When payload vehicle is unloaded, remove
e. Preparing for Travel With Payload. Refer to
cables, chains, snatch blocks and shackles from
payload vehicle. Rewind cables onto winches.
f. Winching-Off Non-Operating Vehicle.
g. Preparing Semitrailer for Travel. Refer to
(1) Position semitrailer in unloading area and
set towing vehicle and semitrailer brakes.
(2) Disconnect and lower each ramp to ground.
2-24. Checking and
Adjusting Suspension Air
Make sure ramp is adjusted to width of payload
Pressure
tracks.
CAUTION
(3) If payload exceeds 55 tons, install support
The M747 semitrailer should not be operated
blocks under each rear comer of semitrailer (Position
with a load of 35 tons or greater if the air
suspension pressure is less than 75 psi or
(4) Position curbing from position A to position
greater than 95 psi.
a. Checking Air Pressure. Check suspension
(5) Attach towing vehicle right winch cable to
pressure daily and each time vehicle is loaded. Be
sure enough time is allowed for air pressure to build
Reeve left winch cable through swingaway and
up to normal pressure (90-120 psi). Apply tire air
platform rollers (para 2-16) and attach cable clevis to
gage to air test valve (fig. 2-8) at bottom of regulator
front of payload vehicle with chain (fig. 2-19). At-
valve in use. Adjust regulator valves if readings
tach hemp rope to loop of left winch cable and pull
exceed following tolerances:
cable to rem of semitrailer. Reeve cable through
Air control Valve at FULL LOAD
855 psi
position
remove hemp rope.
Air Control Valve at HALF LOAD
WARNING
505 psi
position
During winching operations, be sure that all
Air Control Valve at LIGHT LOAD
personnel not involved in the winching
155 psi
position
operations stand clear of the winch cables
Air Control Valve at NO LOAD position
and the payload. A snapped cable or shifting
1005 psi
payload can be extremely dangerous. If the
b. Adjusting Regulator Valve. Loosen jam nut
payload should shift so as to present a
(fig. 2-8) which locks valve
threaded adjusting cap.
hazard, or if any part should fail, stop
Turn adjusting cap to obtain desired pressure: turn
winching operations immediately and
clockwise to increase pressure, counterclockwise to
notify organizational maintenance per-
reduce pressure. Tigthen jam nut when desired
sonnel.
pressure is obtained.
(6) Remove tiedown chains, binders, and
c. Servicing. Open drain cocks slightly on air
shackles from payload vehicle.
reservoirs daily and allow moisture to drain. Close
(7) Station guide on each side of payload vehicle
drain cocks after draining.
to provide directions to winch operator during winch
2-25. Removal of
Spare Tire
operation.
WARNING
(8) Slowly winch disabled vehicle off semitrailer,
Do not drop or push spare tire from semitrailer
following all operating precautions outlined in b
to ground.
above. While winching off with left winch cable,
a. Remove 75 foot rope from front stowage box.
snub vehicle movement, using right winch in ac-
Examine rope for frayed or rotted strands. If in doubt as
cordance with the following procedures:
to the ropes condition, do not use. Obtain rope in good
CAUTION
condition.
Do not permit both winch cables to become
b. Working from either side of the semitrailer gooseneck,
taut at the same time. Allow only as much
double the rope and run the looped end through the tie-
slack in snubber cable (right winch) as
down eye below the roller twice.
necessary: if vehicle is allowed to roll freely
c. Run looped end of the rope through the gooseneck
and the lines snap taut, they may break.
roller, then down through the nearest opening in the spare
(a ) Place enough slack in snub line on right
tire wheel.
winch to permit disabled vehicle to be pulled rear-
d. Take the looped end from the bottom of the wheel
ward approximately four inches.
and secure it to the gooseneck tiedown cleat on same side
(b ) Operate only one winch at a time,
of the semitrailer as the tiedown eye used.
(c ) Winch disabled vehicle rearward with left
winch until snub line starts to become taut.
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