50. GENERAL
Preventive maintenance services, as prescribed by Army Regulations,
are a function of using organization echelons of maintenance. These
services consist of:
_a._ Before, during, and after operation services performed by the
firers and assistants.
_b._ Scheduled services performed by organizational maintenance
personnel (service when filling and charging, and service after six
firing missions).
51. BEFORE-OPERATION SERVICE OF TANK GROUP.
The following services are to be performed before filling, charging,
and loading the flame thrower with pressure, fuel, and ignition
cylinder:
_a. Pressure-tank valve._ Open and close pressure-tank valve to test
for ease of operation.
_b. Threaded connections._ Check all threaded connections for
tightness, using appropriate wrenches.
_c. Tank coupling._ Examine coupling for cleanliness and ease of
movement of lock and cams. (Par 70) Clean if necessary. If washer is
broken, replace, using screw driver to pry out.
_d. Plugs._ Check filling plug and safety-head plug for completeness
of parts (Par 69 _a_) and cleanliness of threads and seats. Clean, if
necessary, with cloth. If rod or rod and chain have broken off and
fallen in tank, turn tank upside down and remove. Remove deflector
tube from head (using hand, not wrench). Inspect to see if diaphragm
is intact. If diaphragm is ruptured, replace the safety head with an
unbroken head. (Par 69 b, c) Reassemble plug, head, and deflector tube
in left fuel tank. (Fig 11) Tube should face to rear and at a 45-degree
angle to operator’s left shoulder. (Fig 18) Screw in deflector tube by
hand; do not use wrench on deflector tube. Tighten lock nut with wrench.
_e. Pressure-tank clamp._ The clamp should hold the pressure tank
tightly in place. If tank is loose, a wooden splint or wedge under the
clamp may be used as a temporary expedient.
_f. Carrier-frame bolts._ Check tightness. Use wrench.
_g. Carrier._ (Par 71) Examine all canvas, webbing, and cord for signs
of mildew, rot, or wear. Replace defective parts. Move flame thrower to
dryer storage if mildew occurs.
_h. Cord (lashing)._ Check for tightness. If necessary, make tighter
and use secure, slip-proof knots. When the tank group is filled with
fuel and adjusted on the firer, its weight should be carried chiefly by
the canvas and webbing, not by the metal frame.
_i. Shoulder and body straps._ Adjust straps to fit firer. (Pars 19 and
71) A loose tank group can cause discomfort or injury when the wearer
changes positions while on a mission. Check presence and condition of
the two pins and two cotter pins which hold shoulder straps to steel
support. Check fasteners.
52. BEFORE-OPERATION SERVICE OF GUN GROUP.
The following services are to be performed before filling, charging,
and loading with pressure, fuel, and ignition cylinder:
_a. Hose nipple, tank end._ Examine to be sure nipple is clean and
not badly nicked. If badly nicked, the nipple may not make a tight
seal at the tank coupling. A leak and loss of pressure may result. See
Paragraph 73 _d_ for repair of the nipple.
_b. Fuel hose._ Examine surface of hose for cracks or other signs of
deterioration. Special attention should be paid to portions adjacent to
the gun and tank coupling, which are subjected to severe flexing. If
hose is defective, replace. (Par 73 _b_, _c_) Do not patch.
_c. Hose nipple, gun end._ Check tightness of threaded connection
between hose and fuel-valve body, using hand or very light wrench
pressure.
_d. Shield._ Remove ignition shield. Check cleanliness of threads
on shield and on ignition-head body. If not clean, use cloth. When
reassembling (Par 18 _c_), shield should turn freely until it locks in
correct position.
_e. Valve lever and needle._
(1) There should be some play in the valve lever. To test, remove
ignition shield. Compress grip safety and valve lever slowly,
observing the motion of the valve needle. The valve lever should move
approximately 1/16 inch before the needle begins to move.
(2) Valve needle should be seated firmly in the barrel nozzle. After
the valve lever is pulled back and released, no play should occur in
the needle. For adjustment of needle, see Paragraph 75 _d_.
_f. Screws._ Use screw driver to test tightness of all screws.
_g. Spring retainer and plug._ Check tightness of spring retainer and
plug (Fig 47) by using hand or very light wrench pressure.
_h. Ignition head._ All exposed surfaces of the shield, nozzle, needle,
and other parts of the ignition head, or adjacent to it, should be
clean. If not, use cloth.
_i. Atomizer hole._ With the fuel valve held fully open, insert a
fine wire in the atomizer hole of the nozzle to clean the hole. Then
use cloth-wrapped splint to remove from the inside of the nozzle any
foreign matter pushed through the atomizer hole. If such matter is not
removed, it may interfere with the closing of the fuel valve needle at
the nozzle. Repeat procedure in _e_ (2) above.
_j. Spring case._ Spring case should turn freely on ignition head. If
it does not, clean any grease or dirt from, surfaces with cloth and
relubricate. (Par 49)
_k. Trigger._ Pull trigger once or twice to find whether it operates
easily and whether it returns to position. If not, clean and lubricate
trigger. (Par 49) Check condition of trigger spring.
_l. Trigger rod._ Check position of the trigger rod when trigger
is pulled back all the way as when firing. The rod should extend
approximately 1/16 inch beyond the end of the lug in the ignition head.
If it does not, bend the rod slightly, reverse position of bearing, or
replace worn parts.
53. SERVICE WHEN FILLING AND CHARGING.
_a. Inspection of fuel tanks._ Just before filling and charging, remove
plugs (Par 69 _b_) and examine interior of fuel tanks to see whether
they are clean and free from foreign matter. If not clean, flush with
gasoline until clean.
_b. Fuel level._ When filling (Pars 37 through 40), see that fuel
reaches the same level in both tanks. If leveling does not occur,
the tank connector may be clogged with foreign matter. If so, clean,
as in _a_, above. After filling, wipe plug seats with a cloth before
replacing plugs. Wipe any spilled fuel from weapon.
_c. Pressure-tank valve._ Before charging the tank group with air or
nitrogen, open and close the pressure-tank valve several times by hand
to be sure it operates freely. If it does not, adjust as described in
Paragraph 66 _d_.
[Illustration: Fig 32. Testing pressure tank and valve, using
0-3,000-pound testing gage from service kit.]
_d. Testing for leaks in pressure system._ After charging, and as few
hours as possible before a mission, use an 0-3,000-pound gage furnished
in service kit to test pressure. (Fig 32) To install gage, unscrew
check-valve cap and screw gage in check-valve body. If pressure has
fallen below that to which the tank was charged (Par 32), a leak is
indicated. Remove gage, replace check-valve cap, and check for leaks
at joints between pressure tank and valve and between tank valve and
check valve. (A wrench should be used to tighten cap on check-valve
body so as to avoid producing an additional leak.) Large leaks can
be felt or heard. Small leaks can be detected by coating joints with
soap-and-water solution. Bubbles indicate leaks. If a leak is revealed
between pressure tank and pressure-tank valve, or between check valve
and pressure-tank valve, replace all three as a unit. If tests do not
show up the leak the tank may have been improperly charged. It should
be recharged and then retested.
54. SERVICE WHEN FIRING.
_a. Failure to ignite._ Pull trigger repeatedly. If ignition cylinder
still fails to ignite, dirt may be wedged in ignition head. Unscrew
shield one-half turn. Screw it back, rapping shield with the hand while
turning. This should dislodge foreign matter. Pull trigger again.
Repeat procedure, if necessary.
_b. Safety head “blows” (breaks)._ If safety head breaks, firing
mission cannot be carried out. On return, have head replaced. (Par 69)
Follow test procedure. (Par 56 _b_)
55. SERVICE AFTER FIRING.
_a. Unloading._ Remove ignition cylinder (Par 30), close pressure-tank
valve, and blow out remaining fuel and pressure. (Par 30)
_b. Removal of equipment._ Release the body straps, then the shoulder
straps. If prone, lie on side and allow tank group to roll off onto
ground. If standing or kneeling, take care that tank group does not
drop on feet or legs.
_c. Correcting or reporting._ Correct any failures or difficulties or
report them as soon as possible to service or maintenance personnel.
_d. Gun._ Remove shield (Par 18) and clean interior of shield with
cloth. Clean holes in shield with wire or wooden splint. Clean external
surfaces of barrel, nozzle, needle, and other parts. Check cleanliness
and adjustment of needle. (Par 75 _d_) Check trigger for operation.
Lubricate. (Par 49)
_e. Fuel tanks and passages._ Remove plugs (Par 69 _b_). Drain
any remaining fuel. Use gasoline to remove residues of thickened
fuels before they have a chance to harden and obstruct passages. If
necessary, fill tanks with gasoline and allow to stand for several
hours, shaking occasionally. Drain and repeat if necessary.
_f. Safety head._ Check head to see if it is ruptured; if it is,
replace. (Par 69) Follow test procedure. (Par 56 _b_)
_g. Pressure-tank valve._ If weapon is to be stored, open pressure-tank
valve and leave it open until next charging.
_h. Carrier._ Scrub, if necessary, with soap and water, or gasoline.
_i. Exterior metal surfaces._ Scrub exterior metal surfaces clean of
fuel to prevent fire hazard. Allow to dry before using again.
_j. General inspection._ Carefully examine all other parts, adjust as
necessary, and replace any which are damaged.
56. SERVICE AFTER SIX FIRING MISSIONS.
After the flame thrower has been used on six firing missions or the
equivalent in training work, experienced personnel should follow these
directions:
_a. Before-operation and after-operation service._ Follow the same
procedures as in Paragraphs 52, 53, and 55.
_b. Test firing (or simulated firing)._
(1) If tactical conditions permit test firing at a suitable test range
(Par 15), fill the fuel tanks with fuel. (Pars 37 through 40)
(2) If test firing with fuel is impracticable, fill fuel tanks with
clean water. (Be sure to dry all parts after test.)
(3) _Remove filling-plug assembly._ (Par 69) Fish out the retainer rod
and chain by means of a bent wire.
(4) Do not unscrew the safety-head plug.
(5) Insert the testing plug with 0-to 500-pound pressure gage (plug and
gage are from service kit) in the filling-plug opening. Tighten testing
plug in seat with wrench.
(6) Fully charge pressure tank. (Par 32)
(7) If test firing with fuel, load ignition cylinder. (Par 18)
(8) Open pressure-tank valve and simultaneously observe pressure in
fuel tanks by reading gage. The gage indicates the pressure in both
tanks. It should be between 350 and 390 pounds per square inch.
(9) Read the gage at the expiration of not less than 5 minutes. The
tanks should have a pressure reading of not more than 390 pounds. If
the pressure continues to increase beyond 390 pounds and the safety
head blows, replace the safety head and the pressure regulator.
(10) Fire by operating controls (or simulate firing if tanks are filled
with water). The burst should last 3 seconds, during which time the
pressure should not drop below 260 pounds.
(11) If the pressure does not conform to the requirements stated in
(8), (9), and (10), adjust the pressure regulator upward or downward.
(Par 67 _d_)
(12) While the above test firing is proceeding, check for leaks at all
joints and connections on the tank group. The pressure system should
be checked by painting the joints with soap-and-water solution and by
looking for bubbles which indicate leaks. For replacement of parts
where pressure leaks, see Paragraph 66. Fuel leaks may be seen without
soap and water. For repair of fuel leaks, see Paragraph 75 _e_. The
nozzle should be observed by removing the ignition shield. Nozzle
leaks are corrected by cleaning, adjusting needle (Par 75 _d_), or by
regrinding. (Par 75 _e_) If this is not successful, replace both needle
and barrel as a unit.
_c. Fuel valve._ Discharge all pressure from the gun by operating the
fuel valve. Carefully remove the valve grip and grip support. (Par
74) Look for signs of leakage at the valve diaphragm. If a leak is
present, replace valve-diaphragm assembly. (Pars 75 _b_ and 75 _c_)
_d. Valve grip._ Disassemble the valve grip (Par 74) and lubricate.
(Par 49)
_e. Carrier._ Tighten the carrier cord.
_f. Gun interior._ If thickened fuel has been fired, disassemble the
gun. All parts should be cleaned of accumulations of dried fuel.
Lubricate (Par 49) and reassemble. If liquid fuel has been fired,
flush gun with clean gasoline. Disassemble only enough to lubricate.
Reassemble.