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I have a question concerning the rear plate bushing of a standard 6V generator.
My generator is original, but it had an old Rebuilt sticker on it so I know it has been messed with at some point. I do know that the flip cap oiler and the bottom plug were removed.
The Parts Catalog and the Service Manuals are no help, as the parts manual doesn’t show the rear plate in an exploded diagram, and the Service Manual simply says to replace the entire rear plate if the bushing is worn.
Now to my question. How is the rear bushing actually oiled? The bushing completely seals off the oil hole after it is pressed into the bore. There is a groove in the bore that would allow the oil to go around the outside of the bushing and down into the large hole on the bottom, but I don’t see what good that would do. Even if there was a plug on the bottom hole, you would fill the entire bottom hole cavity with oil, but it still is trapped on the outside of the bushing.
Hopefully this makes sense, sorry if it’s confusing.
The top hole where a flip cap Oiler should be. As you can see, the bushing seals off the hole. There is a groove in the bore that would allow oil to travel around the outside of the bushing and to the bottom hole. The large bottom hole. Also sealed off by the bushing. If you put any oil in the flip cap, it would simply go around the outside of the bushing and out this hole. There is supposed to be a plug, but I’m not sure what good it would do since even if you filled the entire bottom hole, the groove that goes around the bushing, and the upper hole; the oil is still on the outside of the bushing and isn’t able to get to the armature shaft. However, there is a vent hole that would prevent the bottom cavity from going over half full. This is a photo of a complete rear plate. You can see the flip cap oiler and the bottom plug.
I think that is probably an example of what's called an Oilite bushing or bearing. It's a proprietary material, sintered metal that is impregnated with oil at manufacture. It's actually porous and holds quite a bit of oil. It only needs a few drops now and then.
It just seems really odd that if you were to put a few drops of oil into the flip cap, the vast majority of it is simply going to hit the top of the bushing, follow the groove in the housing around the outside of the bushing, and then drop into the bottom cavity.
I’ve rebuilt several mid 40s Autolite generators that had bushings in the rear plate, and they all used a slotted rear bushing and a wick to draw oil up directly to the shaft.
I just wanted to make sure I wasn’t missing anything.
I would "guess" the original bushing may have been a grooved brass bushing that needed the oil cup and wick? The Oilite doesn't need it to work. At least it "looks" correct with the cup.
When I converted to 12 volt, I combined a later model 12 volt generator with my original. Like Ross said, you can use a bearing instead of a bushing.
I've seen Oilite bushings on things with no access to lube so I wasn't sure about the generator application. Was just my guess. I would think a lubrication point is a plus. I learn a lot from all the experience on this forum.
It was a surprise to me, I couldn't believe such a thing existed. Solid metal, that absorbs oil? What Wizardry is this? It's Magic! My dad had an ancient Dunlap (Sears) wood lathe when I was a little kid. Two oil cups on the spindle with bronze bushings. I couldn't figure out - how do the earl get inside those bearings!?
I guess it takes special machining, and can't be honed per se, or special somesuch. If the micrscopic bearing pore surface is "smeared" it loses the ability to absorb oil.
With the sintered metal saturated with oil you can put a air hose against one side and on the opposite side the oil will bubble out. We have a Roll Compactor at work which has sintered metal filters which we pull a vacuum thru. When powder cakes up on them we have to wash them, once they are washed it takes a oven to dry the water out of them.
