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From: "Steve Tyng" <STyng-at-ACPTrust.com>
Subject: RE: Transmission Basics [TANKS]
Date: Thu, 2 Feb 2006 09:03:36 -0500
Reply-To: tanks-at-rctankcombat.com

Francisco wrote:

> First are these, the same as (or close to) EVs.
> http://www.surpluscenter.com/item.asp?UID=2006020117595767&ite
> m=10-1646&catname=electric

We call those EVX's.  They are slightly less powerful than the EV
Warriors.  They have been successfully used in paintball tanks.  

> I have changed directions and I'm now going for a Churchill 
> Mk VI

Cool tank but narrow for it's size.  Getting everything into it could be

> I am planing on 
> using Plastic Conveyor Tracks like the Hetzer so I will need 
> a belt somwhere in the setup for slippage right?

Usually but I don't recall the Hetzer having any belts.  It may be
relying on the slip clutches in the drill motors it is using.  You
should consider the attachment chain tracks for a Churchill.  It most
closely resembles the WWI style tracks the Churchill used.  It would
look cool.

> If I do a 9 to 1, I will need a 10 tooth and a 30 tooth plus 
> two identical cogs/wheels for the belts right?

Not sure what your describing.  If you want the 9:1 both stages will
have to have a 3:1 reduction.  There's no set rules on the reduction
ratio.  The 9:1 works well when used with 2000rpm drive motors.  Before
you buy any sprockets or pulleys you should layout your hull design in
scale and determine the space available for the transmission sprockets,
particularly the second stage because the space is the tightest at the
drive shaft. You usually have a max sprocket size you can fit on the
drive shaft so your limited on your reduction ratio on the second stage.
You adjust your overall reduction ratio by playing with the ratio on the
first stage.  For example, I was able to fit a maximum size of a 28
tooth sprocket on the Cromwell drive wheel.  It is being driven by an 11
tooth sprocket which gives a 2.55:1 reduction on the second stage.  If I
wanted to set over all reduction to 9:1 I would design the first stage
to a 3.53:1 ratio.

> On the topic of belts what type of belts are used and
> where can I get them?

I use linked belts and get them from McMaster.com.

> On too batteries, what do the veterns recommed 12 volt or 24 
> volt batteries? 

Depends on your motors and the design speed your going for.  The EVX's
are optimized for 12volts.  For your first tank I would stick with

> How many? What type, sealed gel batteries, right?

How many depends on voltage.  What your really interested in is amphr
capacity.  Look for 24amphr or more for a 12volt system.

> What other things do I need to look for when getting batteries? and
> type of charger?

I recommend a smart charger.  Avoid cheap automotive battery chargers.

> Last but not least what do I need to know about bearings?

In order of preference (and cost): sealed ball bearings, bronze
bushings, plastic bushings.

> Thanks for the help everyone,
>         Francisco "Starting over again" Arias, Florida 

Where in Florida are you?  I'm usually in the Orlando area a couple
times a year.

Steve Tyng