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Topic: Am I hallucinating again? (Read 4052 times) previous topic - next topic

keeper63

I seem to recall someone posting a project, a couple of days ago, that they were working on involving a large Panzer toy tank (had 2-3 inch wide tread) they had bought online. I was curious where they got the tank, but I was more curious about their mods.

The poster stated (and posted pictures of) the gearboxes they had modified; he took out all the original plastic gearworks (he said it moved the tank too slow), and replaced it with a belt drive and timing pulleys, and larger motors (some kind of brushed DC motors used in R/C rock-crawlers).

It looked like a fairly impressive mod, but as I started thinking about it, I wanted to ask him if he had actually thought about (or tested) what he was attempting; based on my "off the cuff" calculations, I was pretty sure that if the thing managed to stay together (honestly, I think one or both tracks would likely be shredded or thrown - he was using relay-h-bridges to drive the motors direct from four 9.6 VDC battery packs, no PWM!), it would (theoretically) be able to move 50 feet a second (and that was with a motor speed of roughly 600 RPM - the motors he was using typically run at much higher RPMs than that).

Now - I go to look for the project, and I can't seem to locate it; maybe I dreamt the whole thing? I suppose the poster could've removed it from the whole posting before anybody commented on it...

:)
I will not respond to Arduino help PM's from random forum users; if you have such a question, start a new topic thread.

Tchnclfl

Well, I definitely never saw it!  haha

Sounds like a pretty information-intensive dream! ;D

thegeekway

http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1282281176/5

;)

keeper63

There it is! Thanks, thegeekway! Glad to know I'm not going crazy!

;D

At best he has a 3:1 gear ratio, direct to the tracks; if the motor turns at only 600 RPM (highly unlikely - I figure 2500 RPM would be low), the output at the track sprocket will be approximately 200 RPM. His tank tracks are around 60 inches long (5 feet), so every minute that tank could theoretically move 1000 feet - about 17 feet a second.

Alright maybe that isn't as high as my first guess, and it would probably be even lower as that would be "unloaded" speed, but something tells me that those tracks, and maybe the rest of the tank itself, aren't going to hold up long.

It still sounds like an interesting project...

:)
I will not respond to Arduino help PM's from random forum users; if you have such a question, start a new topic thread.

westfw

Quote
the output at the track sprocket will be approximately 200 RPM. His tank tracks are around 60 inches long (5 feet), so every minute that tank could theoretically move 1000 feet

Doesn't that depend on the ratio of the track sprocket circumference to the track length?  It's like another level of gear (pulley) reduction...

retrolefty

Quote
Am I hallucinating again?


Tell us about the "again" part. I hardly remember the sixties now that I am in my sixties.  ;)

Lefty

UltraMagnus

Interesting.

I tend to leave mechanical things alone, because I tend to break them horribly.  I would love to replace the noisy cheap plastic gears and motors in one of my robots with metal gears and a brushless motor, but I wouldn't have a clue where to start.

P18F4550

#7
Aug 25, 2010, 01:23 pm Last Edit: Aug 25, 2010, 01:24 pm by Funky_Gibbon Reason: 1
Here is the type of gearbox i suspect he's using

http://www.jperkinsdistribution.co.uk/detail.php?JPNO=4401077&activepage=1&Navmain=Cars&subcatname=Tanks

i used to sell the tanks, the fact that you can get replacement gearboxes didn't fill me with much glee, now we only sell Tamiya 1/16 th tanks, 8 times the price but not as fragile but for the price the cheap toy tanks are hackworthy, also the gearbox alone would be usefull for differential drive, maybe a balancing robot

keeper63

Quote
Doesn't that depend on the ratio of the track sprocket circumference to the track length?  It's like another level of gear (pulley) reduction...


Thinking about it now, you're right! That changes things a lot; perhaps it will work out ok for him, then...

:)
I will not respond to Arduino help PM's from random forum users; if you have such a question, start a new topic thread.

keeper63

#9
Aug 25, 2010, 09:15 pm Last Edit: Aug 25, 2010, 09:33 pm by keeper63@cox.net Reason: 1
Quote
i used to sell the tanks, the fact that you can get replacement gearboxes didn't fill me with much glee, now we only sell Tamiya 1/16 th tanks


I'm looking at the link you posted, and I am not sure those are the same tanks; the dimensions of those tanks seem far smaller than the one that Harjit Singh is using in his thread. His gearboxes are also plastic, not metal.

His tank appears to be something like 1/6 or 1/8 scale; maybe 1/10 - not sure. I am seriously wondering where he got such a large toy tank, and what it cost; it would be a great Arduino robot platform...

:)

[edit]I think I found it:

http://www.bananahobby.com/1139.html
http://www.bananahobby.com/1140.html

Not a bad price, either...[/edit]
I will not respond to Arduino help PM's from random forum users; if you have such a question, start a new topic thread.

P18F4550

Very good Cr0sh, yeah you can go down to 1/4 scale if you have the $$$,
im not so much into the tanks, more this
http://www.tamiyausa.com/product/item.php?product-id=56323
and this trailer
http://www.tamiyausa.com/product/item.php?product-id=56306
im busy modding the tractor to make it autonomous

keeper63

Quote
Very good Cr0sh, yeah you can go down to 1/4 scale if you have the $$$,


I saw some of those in my searches; the price goes up into the stupidosphere for those, though. If I needed a tracked vehicle that big and bad, a stripped-down ditch-witch might be cheaper; kinda like what Christian Ristow did for Subjugator.

I've just been looking around for smaller tracked vehicles; even into the mid-range size, it would likely be cheaper to go with inside-out or dual-sided timing belts with extra cleats, and a custom pully suspension system.

Cheapest of all, though, with nearly the same capabilities, is a 6WD skid-steer platform - like the CMU Terragator used.

:)

I will not respond to Arduino help PM's from random forum users; if you have such a question, start a new topic thread.

jds

#12
Aug 29, 2010, 10:31 pm Last Edit: Aug 29, 2010, 10:31 pm by jds Reason: 1
Here are a couple of tanks that might interest you (my Blog about R/C):

http://www.rc-international.info/Blog/category/Tanks.aspx

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