TM 5-3431-207-15
Section IV. OPERATION OF EQUIPMENT
(1) Attach welding cables
to
welding
20. General
generator output studs.
a. The instructions in this section are published for
the information and guidance of the personnel
(2) Attach lug end of work cable to work
responsible for the operation of the welding machine.
terminal and clamp end to work metal.
b. The operator must know every operation of
(3) Attach lug end of electrode cable to
which the welding machine is capable. This section
electrode terminal.
gives instructions on starting, stopping and various
(4) Place polarity switch (fig. 3) in up or down
operations of the welding machine.
position and check the polarity of the
electrode.
21. Starting
(5) Place job selector (fig. 3) in proper
a. Preparation for Starting.
position for weld to be made.
(6) Set current control (fig. 3) so that colored
(1) Check and then connect all cable leads to
arrow on handle corresponds with the
the welding machine.
color at which the job selector is set.
(7) Use the portable job selector for remote
(2) Connect the machine to the correct
work as shown in figure 6.
source of power.
b. Welding Methods.
b. Starting the Motor-Generator.
(1) When welding in the vertical and
The machine may be started by simply pushing the
overhead position, the operator should
start button.
have a strong digging are for penetration
and a cool arc to let the molden metal
Caution: Once the machine is started, the
solidify. With the job selector set in the
direction of rotation should be checked immediately
red section for a medium-low open-circuit
with the manufacturer's instructions or directional
voltage (overhead and vertical setting),
arrow. On three-phase motors such as this Model
the electrode is pulled away, the current
LA-300, direction of rotation may be changed by
will cut down to a lower figure, cooling the
interchanging any two input leads.
puddle and letting the metal solidify. The
"in" and "out" motion, combined with the
22. Stopping
normal whipping technique, gives the
operator complete control over the puddle
The machine may be stopped by simply pushing the
during vertical and overhead welding.
stop button.
(2) When welding downhand or for sheet
Caution: If the welder is suddenly disconnected
metal application. no change of current is
desired. During welding for this purpose,
from the line, the thermostats have undoubtedly
the job selector should be set in the black
tripped and .the trouble should be located at once.
section for a medium-high open-circuit
The thermostats automatically reset when the motor
voltage( normal welding range). Little
returns to a safe temperature and no manual
current range will result from lengthening
operations are required to restart the machine
or shortening the arc when the job
except pushing the start button.
selector is in this position.
23. Operation Under Usual Conditions
(3) When a "rubbery" arc or large electrodes
a. D. C. Welding Machine.
and high currents is desired for the
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