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#### Georgia Tech

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But I'm interested to know one more thing about DC serie motor.

At a fix given current, maybe 1000A, what determines the capacity of a motor to sustain his max torque over the increasing rpm?

I read someting about resitivity of motor in ohm (mΩ) vs voltage given to the motor vs voltage produce by the motor, but it's not clear for me.

Also, the number of commutator segments can play a role?

I need to understand why a motor compare to another one fo the same voltage and the same Amp lose his max torque before the second.
Bellow, an exemple of torque lost at high rpm!

This is sort of two questions here..The ability for ANY motor to sustain a certain torque is a function of how much current it can withstand with out burning up! This has to do with the wiring and how thick the gauge the windings are. also the mass of the motor in its ability to disibate heat. Bigger motor usually can sustain larger torques due to Bigger and heavier winding and more mass for the Heat to go. Larger motors also tend to be more effecient too.

Now If your asking what does it take for a Series or SepEx to sustain torque in an increased RPM that has to do wit the Voltage accross it. The higher voltage with the same 1000 amps will run at a higher RPM. this is a linear realtionship for the most part.

Here is something to think about for given motor:
Volts equates to RPM
and
Amps equates to Torque.

Volts X Amps equals Watts
Torque X RPM/5252 equals Horse Power

#### Georgia Tech

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It seem you are right Major! (see picture). Maybe it's more 25 slots and 50 bars.

After all this learning (thanks), I have more ability to seach a powerfull forklift motor for an street EV aplication.

And after all this explanation I realise the best forklift motor for high torque at high rpm for a 1000A/156v configuration was the GE 11" motor I found few weeks ago.

Large diameter for high torque, large brush for high current and 49 big cumm bars for sustain high torque at high rpm.......
Unfortunately, it need new flange on both side and it's lot of money in material and machining.

So, one more time, thanks Major.... this thread can probably help many other guys to find the best forklift motor for street EV.

This last photo, is the GE 11 that I have. I SWARE it looks EVERY bit the same as a WARP 11 motor.. they both have the SAME internal specs too..

#### Georgia Tech

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Not exactly.............

GE 11": 49 bars and 4 big brush (4 poles).

Warp11: 25 bars and 8 brush (4 poles).
The GE 11" does infact have 8 brushes two per pole...at least mine does...

I was told that the Warp 11 had 49 bars as well who told you it only had 25?

#### Georgia Tech

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yabert i think I see from your photos...you have the one piece brush design i was told by the people at warfeild to MAKE SURE that this was upgraded to the 2 piece brush design...this would then be like the WARP 11.

#### Georgia Tech

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Major,
how do you have an armature design that has a different number of Commutator bars and a different number of armature slots?
How does this work?

what advatages does this have over the same number bars and same number slots? like 49 and 49 in the GE 11?

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