Re: High-Low gears [TANKS]

[Frank Pittelli <frank-at-rctankcombat.com>]

erik kump wrote:
> I kept coming back around to the 
> notion of having a two or three speed transmission.

 > Can the guys who have 'been there' give me a thumbs up or down as
> to whether or not they feel that this could be an asset? 

The short answer is YES.

I think it is generally agreed that it is beneficial to have multiple 
speed or power settings (not always the same thing) in order to (a) 
conserve energy and (b) handle special circumstances (ie. rough terrain, 
attack, retreat, etc).  The real trick is: how to do it effectively and 
reliably.

As I see it, there are three basic approaches:

1) use a fixed transmission and vary the voltage to the motors,
2) use a fixed voltage and transmission, and vary the motor windings,
3) use a fixed voltage and change the gear ratio of the transmission.

For an effective solution, all approaches need to be tuned to deliver a 
"normal setting" that can be used during normal operations to conserve 
energy and a "high setting" that can be used for pursuit or rough terrain.

My personal preference is (1) or (2) because they are very simple to 
build and maintain, once the proper transmission ratio is found.  But, 
anyone with reasonable mechanical skills can also make (3) work well.

In both cases, however, the key to success is finding the right 
transmission ratio(s) for the motors/batteries/tracks/vehicle being 
used, under the expected loads.  In theory, the ratios can be 
calculated, but at some point you have to simply put it on the field and 
measure the performance to truly find the optimal settings.  For that 
reason, I have always recommended that no matter what design you select, 
ensure that it is flexible enough to allow you to change things around. 
  Even only a couple basic field trials and changes can significantly 
improve the performance of the system.

Currently, all tanks equiped with EVs -at- 12v are using approx 9:1 gear 
ratios.  It is very possible, however, that we might see higher 
efficiency, higher speeds and higher power if we run them -at-24v with a 
different ratio.  The only real way to know is to re-configure a tank 
and test it on the field, which hopefully will be done by a number of 
battlers in the next couple months.

        Frank P.