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Old 10-26-2003, 05:13 PM   #1
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Default Motor brush help info?

I was messin around with some motors an realized that some would not give full power if you soldered to the wire tabs vs if you directly connected power to the brush wires.

I guess some hoods do not conduct as much power as others. Also from what I hear the brush wire that you solder can only carry 5 to 7 amps.

What is the best solution if any to correct the problem of getting full power from wire solder tabs to the brushes?

Coop
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Old 10-27-2003, 09:33 AM   #2
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Old 10-27-2003, 11:06 AM   #3
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Default Motor brush help info?

gcooper;

I ALWAYS solder my Brush leads to the Tabs where the power wires are soldered. Can't get more direct than that.
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Old 10-27-2003, 04:46 PM   #4
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Default Re: Motor brush help info?

Quote:
Originally posted by popsracer
gcooper;

I ALWAYS solder my Brush leads to the Tabs where the power wires are soldered. Can't get more direct than that.
Pops,

I do too. I heard that the leads only could carry 5 amps. Which had got me to think where does the motor get the rest of its power. If it is not the 5amp lead, then its through the endbell plate from the brush to the solder tab. If the plate does not conduct well then you are not getting full power to the motor.

I was wondering if there was a trick to getting around this.

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Old 10-27-2003, 05:29 PM   #5
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Well, my understanding of it is that the brush hoods do most of the work of conducting current to the brushes(which makes Trinity's use of copper for the brush hoods make more sense).....
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Old 10-28-2003, 11:47 AM   #6
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Default Motor brush help info?

gcooper;

Not knowing the exact Gage of the shunt wire, I would guess that at least 5 amps is reasonable.

Electricity will ALWAYS take the path of least resistance.

So:
If you solder the shunt to the Motor tabs, you provide 2 paths for the current to flow and possibly less overall resistance.

Solder the shunt to the hoods next to the brush and ALL of the current must travel through the Hood, until it reaches the Brush.

Is one method better than the other? This I cannot say.
But as current demands increase, theory says that soldering the shunts to the Motor tabs should be more efficient.

Last edited by popsracer; 10-28-2003 at 12:17 PM.
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Old 10-28-2003, 11:59 AM   #7
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I don't agree 100% with the brush shunt rating. The reason being is that when I had a Fantom dyno I ran a motor just hooking the leads to the shunts. Then I did it just hooking to the brush hood without the shunt connected. With the connection to the shunts it made a big difference in the readings (higher).

I know it is not a scientific test however, we need to give the shunts more amp carrying capabilities than they deserve. Now maybe they can only handle 5-10 amps for so long.
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Old 10-28-2003, 12:43 PM   #8
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Kraig - Is this why trinity has the dual shunt brushes? I just thought it was another pathetic marketing stunt that was completely usless.
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Old 10-28-2003, 03:27 PM   #9
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Default My $.02

The shunts can carry up to 10 amps (acording to Big Jim) because of their size. Yes they can carry most of the current. The hoods do a lot too.

So you DO have 2 paths, shunt and hood. A motor will always be better with clean brushes and the insides of the hoods clean. YES this is why copper is better for brush hoods. I clean my brushes and the insides of the hoods every rebuild or even clean up.

I THINK soldering the brush wire to the tap or next to the hood makes no difference at all. The endbell is all metal or copper so the 1/4 inch not going to make a measurable difference.

Resistence would be 1/2 when using both paths instead of just the hoods or just the shunt. I think those brush dampers make a big difference too. Better connection to the brush.

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