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Replace brushes when they wear within 1/4” of the pigtail. A complete set of replacement brushes should be kept on hand. Lincoln brushes have a curved face to fit the commutator. Have an experienced mainte- nance man seat these brushes by lightly stoning the commutator as the armature rotates at full speed until contact is made across the full face of the brushes. After stoning, blow out the dust with low pressure air.
To seat slip ring brushes, position the brushes in place. Then slide one end of a piece of fine sandpaper between slip rings and brushes with the coarse side against the brushes. With slight additional finger pres- sure on top of the brushes, pull the sandpaper around the circumference of the rings - in direction of rotation only - until brushes seat properly. In addition, stone slip ring with a fine stone. Brushes must be seated 100%.
Arcing or excessive exciter brush wear indicates a possible misaligned shaft. Have an authorized Field Service Shop check and realign the shaft.
Idler Maintenance
CAUTION
Before doing electrical work on the idler printed circuit board, disconnect the battery.
When installing a new battery or using a jumper bat- tery to start the engine, be sure the battery polarity is connected properly. The correct polarity is negative ground. Damage to the engine alternator and the printed circuit board can result from incorrect connec- tion.
1.The solenoid plunger must work freely and not bind. Dust the plunger about once a year with graphite powder.
2.Proper operation of the idler requires good ground- ing of the printed circuit board, reed switch, and battery.
3.Idler solenoid is activated for high idle.
4.If desired, the welder can be used without automat- ic idling by setting the “Idler” switch to the “High” position.
Nameplates
Whenever routine maintenance is performed on this machine - or at least yearly - inspect all nameplates and labels for legibility. Replace those which are no longer clear. Refer to the parts list for the replace- ment item number.
Purging Air from Fuel System (Perkins 104-22 Engine)
WARNING
Keep fuel clear of open flames or arcs, allow engine to cool before working on the fuel system. Wipe up any spilled fuel and do not start engine until fumes clear.
If the engine is running rough and you suspect air has been trapped in the fuel system, (e.g. the engine was allowed to run out of fuel) perform the following steps using qualified personnel:
1.Loosen by two or three turns, the vent screw (Figure D.1) on the fuel inlet connection.
Vent Screw
Priming
Lever
FIGURE D.1
2.For Engines Equipped with a mechanical fuel pump:
Operate the priming lever on the fuel lift pump until fuel, free of air, flows from the vent point. Tighten the vent screw. If the pump is at the point of maxi- mum lift, it will not be possible to operate the prim- ing lever. If this occurs, turn the crankshaft one revolution.
For Engines Equipped with an electric fuel pump:
Operate the electric fuel pump by turning the “Ignition” switch “ON” until fuel, free of air, flows from the vent point. Tighten the vent screw.
3.Contact your Perkins Engine repair facility if prob- lems persist.
CLASSIC 300D
