Re: Questions about past email and other things [TANKS]

[Rodolphe GREMEAUX <r.gremeaux-at-wanadoo.fr>]

Thanks Joe for this detailed answear.

Joe Sommer a écrit :

>
> At 08:49 PM 3/1/2005 +0100, Rodolphe GREMEAUX <r.gremeaux-at-wanadoo.fr> 
> wrote:
>
>> i've some question about this email
>>
>>         Most current tanks use about 4 inch diameter drive
>>         sprockets turning at about 400 rpm.  That produces
>>         4.76 mph.  I estimate that you need about 400 in-lbf
>>         sprocket torque per track to perform a full skid turn.here is 
>> there a link between 400rpm and 400in-lbf to make a full skid turn ?
>
>
> no
>
> The estimate of 400 in-lbf was based on two observations.
>
> Hetzer #T010 originally had 12V Makita drill motors (320 in-lbf each
> with 1:1 drive ratio) and did not have enough torque for skid turns
> in tall grass.  I switched to 24V Makita drill motors (476 in-lbf each
> with 1:1 drive ratio) and it has plenty of torque.
>
> Secondly, most MAG tanks use EV Warriors at 12V (691 in-oz
> with 9:1 drive ratio = 389 in-lbf) and they have plenty of torque.
>
>> By the way is the total weight of the tank is inclueded ? Is it 120 
>> pounds ?
>
>
> This simple estimate is based on an average size tank that weighs
> about 80-120 pounds with about 4 inch diameter sprockets and
> about 18 to 24 inch ground contact length.
>
> Torque required for full-skid turns is:
> proportional to weight (higher weight requires higher torque)
> proportional to ground contact length (longer track requires higher 
> torque)
> proportional to diameter of drive sprocket (larger sprocket requires 
> higher torque)
> proportional to lateral friction of track (higher friction requires 
> higher torque)
> inversely proportional to track guage (wider separation of tracks 
> requires less torque)
>
>> Also a thing i don't get about the specs :
>> the spec of the EV warrior are at 12V
>> Stall torque : 691 in-oz
>> Peak HorsePower : 0.38 hp
>>
>> The mini EV motor are :
>> Stall torque : 64.64 in-oz
>> peak ph -at-12v : 0.313 hp
>>
>> How could the stall torque on one motor be ten times biger than the 
>> other motor and
>> how peak horse power could be kind of the same.
>
>
> Stall torque occurs at 0 rpm.  It does not occur
> at maximum power.
>
>> An other thing, could we underpower a motor:
>> if i try to make working a 24V dewalt motor at only 12v?
>> Will it work? if yes how good ?
>
>
> bad idea
>
>> Also, is it the shortest diameter sprocket wheel where should be 
>> connected the motor
>> or the longuest sprocket wheels ?
>
>
> see above
>
> Joe
>
> **********************************************
> Joe Sommer, Anvilus Machine Works
> 2378 Nantucket Circle, State College, PA 16803
> 814.234.4773     anvilus9-at-adelphia.net
> http://www.anvilus.com
>
>
>
>