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-   -   Improper gearing and power draw (http://www.chiefdelphi.com/forums/showthread.php?t=128512)

MysterE 05-04-2014 07:36

Improper gearing and power draw
 
Ok

Quick question; on the field we are drawing way too much power and as a result lose the ability to do much. This is, as was told to us, the result of improper gearing (6:1) and six inch wheels. We have two cims and one mini on each Transmission, one Cim from the shooter, a compressor, and an Andy Mark motor driving our pickup.

We are considering removing both mini cims and installing omni wheels on the back of the bot to help lower traction and lower the power draw. Does this sound like something that would help?

IKE 05-04-2014 07:47

Re: Improper gearing and power draw
 
That might help, but ratio would be better. You are geared for free speed of 18+ feet per second free speed. This is really fast for a non shifting robot. Any pushing matches will likely cause your snap action breakers to trip. If you were popping your main, pulling the minis might help, but if you are tripping the snap action, you really need more ratio.

MysterE 05-04-2014 07:55

Re: Improper gearing and power draw
 
Fortunately nothing is snapping.. the log just shows an inbordinate drop in power when we start moving around.

D.Allred 05-04-2014 08:00

Re: Improper gearing and power draw
 
Do you have 4" wheels available? You would still be 12fps.

David

MysterE 05-04-2014 08:13

Re: Improper gearing and power draw
 
Yeah.. four inch would give us clearance problems. The gear boxes are a bit below the frame

Daniel_LaFleur 05-04-2014 08:34

Re: Improper gearing and power draw
 
Quote:

Originally Posted by MysterE (Post 1369471)
Fortunately nothing is snapping.. the log just shows an inbordinate drop in power when we start moving around.

By drop in power, I assume you mean a drop in voltage.

If you are not direct driving your wheels you may be able to add another output ratio between the gearboxes and the wheels by changing pulley/sprocket sizes.

Ether 05-04-2014 09:15

Re: Improper gearing and power draw
 
Quote:

Originally Posted by MysterE (Post 1369468)
...improper gearing (6:1) and six inch wheels. We have two cims and one mini on each Transmission, one Cim from the shooter, a compressor, and an Andy Mark motor driving our pickup.

We are considering removing both mini cims and installing omni wheels on the back of the bot to help lower traction and lower the power draw.

You didn't say: Is this a 6WD or 4WD? Long or wide?



ktorrico 05-04-2014 11:50

Re: Improper gearing and power draw
 
Are your speed controllers in "brake" mode?

We had a similar problem at our first district event, and switching to "coast" mode fixed the problem.


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