Burnt out motors

[swanaldo]

Tut. Trev i want to have a good chat with you soon about gears and stuff me old pal. Might even pop round for some of them there chips your good lady does.

[woody]

LOW is SLOW

http://www.weirdrichard.com/gears.htmhttp://www.weirdrichard.com/gears.htm

So ...as I see it...and Kane.

A LOW gear ratio ie; 15:1, will load the motor less than a HIGH gear ratio ie 5:1

(Message edited by woody on January 14, 2009)

[woody]

Edit to above ..
15:1 means.. to me..15 Turns of the motor one turn of the wheel.
5:1 means 5 turns of the motor and one turn of the wheel.

[grant_ploughbot]

GEAR DOWN
To adjust gears in such a way that the DRIVER ( OUTPUT ) gear goes slower than the DRIVING ( INPUT ) gear. MORE POWER!

Considering that statement came from the same page i wouldnt trust it too much. Its states in my Uni handbooks a higher ratio is the higher the actual ratio as trev said.

[woody]

Edit ...

(Message edited by woody on January 15, 2009)

[mightymouse]

What have I started - it was only a long running joke between Swanny and me.

You are welcome round any time bud, and the spuds are ready for peeling. yum yum

[woody]

I think this disagreement / misunderstanding is based on the terms used / misused ....

Ratio and gearing are two different things.
Low ratio = High gearing
High ratio = Low gearing

Trev said A low gear ratio will also cause a motor to run hot

When it should perhaps have been written thus ...A low ratio / high gear will also cause a motor to run hot.

and I should have written.

A LOW gear / High ratio ie; 15:1, will load the motor less than a HIGH gear / Low ratio ie 5:1

So we are all saying the same thing but have been using incorrect terminology.

[terrorhurtz]

A couple of other things to consider regarding motor heating:
The ESC - if the esc has a low switching frequency, it will tend to heat the motor more. A Vantec has a standard switching frequency of only 300 Hz, which will result is more heat than necessary being generated by the motor at part throttle. The new Wottys are around 12 kHz IIRC, which results in a resonably smooth output current at part throttle. Much better. The IFI Victor/Thor is especially bad in this respect - only 75 Hz.

Another thing that has a big effect, of course, is how much throttle you use. With reasonably powerful motors (e.g. Bosch or better), you should be able to get wheelspin at low speeds at half throttle or less. Using more than this generates substantially more heat in the motors, without any significant increase in thrust. Learn to be gentle with that throttle.

Ive being trying to get myself to back off the throttle in the last couple of fights (Boschs at 33V are a little marginal), and its surprising how little you need.

Also note that gyros can give the motors a hard time, especially if the gain is turned up, as they can send frequent large bursts of power to the motors to maintain course.