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Old 12-06-2011, 10:34 PM   #5
TerryH
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Join Date: Oct 2010
Location: Springdale, AR
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Default Re: D&D PDS High Speed Motor and 8:1 High Speed Gear Experiment...

Quote:
Originally Posted by Andy4639 View Post
. Is this cart running the speed senor?

No. The motor has the harness but I will not be using the speed sensor or any regen.

Did D&D give you any RPM #'s are speeds to stay under?

They say that they would like to see me not exceed 6000 rpms for a sustained period of time.

If you got a high speed motor with high speed gears want this mean it will take more RPM's to get moving which in return make the cart run higher RPM's to maintane a steady speed?

No,not really. The rpm is the rpm. It will take more torque at a lower rpm to move the cart. Getting the cart going with the higher gear is all about the torque of the motor not the rpms. The higher gear will in fact allow the cart to go faster at a lower rpm. With the stock gear the motor turns 12.44 times for every time the tires turn once. That will go down to the motor only turning 8 times for every 1 time that the tires turn with the new gear set so the rpm will go down but it will take more torque to make the cart move..


Here are the numbers from the speed calculator...

RPM/Gear/Tire Dia./Speed
6000 12.44 20" 29 mph
6000 8.1 20" 44 mph

4000 12.44 20" 19 mph
4000 8.1 20" 29 mph

This is truly the goal here, for the cart to be able to run a steady 30-35 mph at around 4000-5000 rpm instead of the 6000-7000 that is required with the stock gear. The eventual top speed of the cart will also go up because the motor will most likely turn well over 6000 rpms but it just can't be run wide open all the time. No motor will live very long at those rpms.

This is all part of this being an "experiment." It all comes down to this: Does the motor/controller/battery combination produce enough torque to pull the cart out of the hole and up to cruising speed quickly enough to make me happy with the 8.1 gears and does the combination produce enough horsepower to push the cart up to the maximum rpm of the motor without it taking 5 miles to get there? That is the question.
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