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3 INTRODUCTION
MED 304 is a wire feed unit for MIG/MAG welding.
It is a component of the A--10 system.
MED 304 has an electronically controlled electric pusher motor that advances the
wire through the welding hose to the gun.
3.1 TECHNICAL DESCRIPTION
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MED 304 has two motors (1) and two pairs of rollers, each comprising a feed roller
(5) and pressure roller (4). The rollers have toothed rings. The motors drive the feed
rollers, which in turn drive the pressure rollers.
The motors are connected in series and each contributes the same driving force.
Any slip due to differences in the diameters of the rollers will therefore not affect the
uniform feed.
The pressure rollers are incorporated in a bogie that is supported so that the pres-
sure exerted by both pairs of rollers is the same.
The bogie is mounted on a lever, which is fitted with a spring--loaded arm ( 3). This
unit can be easily removed, for example when changing the wire size.
The pressure exerted on the wire by the rollers is controlled by a knob (2), that acts
on the spring--loaded arm. There is no need to adjust this knob to remove the pres-
sure roller. This means that the pressure is unchanged when the pressure roller is
replaced.
The wire r uns in grooves in the rollers, and each wire size has its own groove profile.
The lateral position of the feed roller is adjusted using spacers so that the correct
groove is aligned with the wire.
The pressure roller automatically positions itself correctly.
MED 304 is equipped with inch start, which ensures smoother arc ignition when
welding with large diameter wire. The units also provide 2 stroke or 4 stroke arc con-
trol.
To simplify the replacement of large diameter wire the MED 304 has reversible mo -
tors. These allow the wire to be reversed out of the welding hose.
The wire feed unit is divided into two sections. One section contains the electrical
equipment, protected by a panel. The other section is protected by a lockable panel
and contains the wire feed unit and connection socket for the welding hose. Above
the connection socket are switches for selecting 2 stroke or 4 stroke arc control and
for inch start.
Control equipment.
The electronic components are mounted on a circuit card, which is held in place by
two reatiners and screws. The wiring is connected by spade connectors and multi--
pin connectors.
GB