klien 300 amp welder generator

i recently purchased an old klien 3 phase 480 gen /300 amp dc welder this machine used to have a 20 horse electric drive motor on it i have replaced it with a gas engine it welded great for a while but then qiut . th

Re Klien 300 amp welder generator. Little bit of my experience of welder gen. after some 30 yrs welding.NB make sure you immobilise the engine before making any adjustments to the brush holder. Some times when you strike your welding electrode especially with a large diameter electrode - say 6SWG or 4SWG, the sudden call for high amps will twitch the brush holder forward or back a fraction. Consequently lowering the amps or losing them altogether. May be an idea to check and see if that brush holder has moved. This little story came about after some kids were supposed to have pushed a 300 amp Licoln that was on hire into the river. Anyhow the welder was fished out of the river and had a complete re-build, just like new, but the the engineers didn't tighten up those brush holder bolts enough. If you've lost your amps check that the position of the brush holders has not moved. It only has to move a small fraction to make the difference between burning a hole in inch plate or not burning a hole in baked bean can. I believe it has something to do with the phase angle but perhaps someone else can help you on this one. Chas

Yes, brush phasing can cause problems. The electric car people are worried about such things when running at high power levels.

Brushes on a multi bar ( DC ) commutator must be phased to cross into the next bar when the field magnetism is at it's lowest strength. This location is slightly different to the mechanical center of the armature and field poles. ( think of spark advance in a gasoline engine)

Some motors use interpoles to kill the magnetism even further while the brush passes onto the next bar. Out of phase bruses will arc badly and wear quickly.

It's hard to say what is wrong with this particular gen, it could be a brush or exciter gen problem. Since this was a electric motor/gen setup, did you modify the exciter circuit? Also, is the gen rotating the same direction? Brush phasing is different depending on rotation.

Harold