go-tank

[B.M.800]

Check this out over at atltf this guy is building a tracked thing. Pretty cool, maybe get some idea off of it?

 

[machinist@large]

Check this out over at atltf this guy is building a tracked thing. Pretty cool, maybe get some idea off of it?

Nice link!! His efforts building his own tracks are well thought out and built, but may, if anything, down play the amount of effort he's put into his rig so far. He doesn't give much detail on how well his shop is equipped; pressing and flanging the track bars alone was a lot more work than he commented on.

His description of his trials and travails concerning the drivetrain are real issues for anyone thinking of going into a project like this; I know that I don't have definite answers; I'm still looking around & gathering data. But I'm guessing that something like that is a little more than JR is thinking of as a start....

 

[jroberts]

Yea just a bit. Like I said before the only equipment I have is a welding machine and a hack saw lol. No fancy bending tools or anything thing like that

 

[firemanjim]

If it were easy, EVERYBODY would be doin it..... It takes time, patience, and a lot of thought, partly read as $$$.....

 

[jroberts]

Don`t mind it taking a long time or being hard to do. Plus easy wouldn't fun. It's just that I want to stay away from having to make bends or making my own pins cause I have no access to lathes or bending machines. Though the link that B.M. linked gave me some good ideas.

 

[firemanjim]

Man, you dont need a shop full of tools to do it... You need a brain.... So you have basically everything you need. You dont need to bend all that stuff! Sure! It does look great, but using that noggin on your shoulders can get you something similar . For the "leading lip" , simply weld another strip of flat stock with an over hang to make the lip. The trailing ,upward lip, simply bend about 1/2" back, to a 40-45°.... in a vise, OR since you woud be making a BUNCH of them, build a jig w/ a metal brake at the top,working down.... Slide a plate in , the force coming down also pushes plate back when bending, to ensure ALL the bends would be in tbe SAME location.....
No pins NEED to be made... think GRADE 8 bolts......



EDIT.... I thought I said no bending, but I said no need to bend ALL of it..... lol
It wouldnt be that bad....

 

[jroberts]

hmm good point, now the challenge is convincing the fiancé

 

[porsche930dude]

i will be starting on a mini tank in a couple weeks. ill start a build page when i get going on it. I have a good plan for tracks but if you want to build it without tracks check this out for a good drivetrain setup
http://www.oldminibikes.com/forum/more-than-two-wheels/87281-mini-6x6-roamobile.html

 

[machinist@large]

The link that BM provided to the "atltf" forum is great; I think the OP there has put a great deal of effort into his project. But as JRoberts has said, he isn't quite ready to dive in to that depth yet.

I've been noodling over how to build some form of tracked vehicle for a couple of years; off and on I've had time to kill, but no $$.
I've also been known to recycle/ repurpose stuff (re; other people's junk), and I've been thinking about the whole differential braking thing. When ever someone uses it, it takes a lot of power to turn and move at the same time. Why not go back to the way bulldozers operate; using some form of slipping mechanisim to unload the drive on the side in the direction you wish to turn, thus not bogging down the rest of the drive train.

The idea I'm talking about isn't mine, and it's far from new; it's just what comes to mind when I think about the drive train on my Ex Mark commercial lawn mower....

Photo 1] shows a snap shot of the layout from the rear; photo 2] shows that sides drive fully engaged; there is enough slack in the brake linkage that the adjuster for the individual band brake for that wheel is just going along for the ride, hence no gap at the adjuster wing nut.

Photo 3] is the belt completely disengaged, and the brake band for that side totally locked up. The angle difference for the brake lever is small, but you can clearly see it in the thumbnails; this is all controlled by a hand lever, with about double the effort of a typical mountain bikes brakes (mine) at full stop. Photo 4] is a top view of the entire side, and photo 5] is a color shot for anyone who hates B&W photo's.

Basically, for a tracked vehicle, save yourself some grief and skip the differential. You will be controlling the differential action as part of your steering if you go with some type of clutch; and yes it can be as simple as just slipping the drive belt on that side. You will need brakes, for each side, but that can be as simple as the basic band brakes used on a lot of basic karts, as long as the mechanical advantage is there.

I know, I haven't built anything on the forum yet; but here's my ideas for a tracked vehicle drive train, using lawn equipment parts (which, if I'm not mistaken, are kind of popular as source material around here).

I've got some ideas on alternate tracks (i.e. off the shelf); the problem is they want more for about 50 lbs of rubber in a track than I paid for the last set of load range D commercial tires for a company van (~$600.00 EACH!!!!!), so that's still an obstical to be dealt with......

Hope this helps someone..... Pat

 

[Poboy kartman]

That's a good idea- now couple that with band brakes on the same inkage and you just push forward on both levers to stop.

 

[machinist@large]

That's a good idea- now couple that with band brakes on the same inkage and you just push forward on both levers to stop.

Actually, push forward to go, pull backward to stop. That's how the Struck kit 'dozers with belt drive work, with an auxiliary brake pedal for total stop, from what I've read. This design can be modified with a reverse drive, as well; the Struck 1600 plan layout that 'Sid linked for us has that as standard.

Sticks in neutral, no motion. Push forward to start forward; the harder you press in a given gear, the less slippage. Pull back for reverse. Add separate pedals for the brakes, each side, and you just saved yourself a couple of grand in hydraulic components, plus the nightmare of keeping it all straight. If you do want hydraulics, it becomes a small sub system that's a lot easier to set up and integrate.

Pat

 

[firemanjim]

http://www.youtube.com/watch?v=mrAdCR2uAYM&feature=youtube_gdata_player

That is powered by a vw 4 cylinder engine and a swing axle trans. I had pics of this thing but cant find them. It uses basically a set of turning brakes to steer and has a small hydraulic pump driven off the engine for the blade ...... Pretty neat..... and works good. On these diffs, if you lock one axle, ALL the power goes to the other axle, with no real drag to to engine. Tractor pull tractors steer with brakes too....

 

[fowler]

I would have to agree in the differential steering bit

Although what u guys are calling differential isn't really

If a dozer were to simply disengage one track them it would just drive straight
They do that when we change tracks

True differential steering allows u to have power to both tracks at all times
And trying to understand it is quite hard without seeing it in person
http://m.youtube.com/watch?v=A5_iNL9q18Y

Here's a short vid that brefly explains it
It is the best form of steering in a tracked machine
But is way beyond any DIY machine

 

[machinist@large]

http://www.youtube.com/watch?v=mrAdCR2uAYM&feature=youtube_gdata_player

That is powered by a vw 4 cylinder engine and a swing axle trans. I had pics of this thing but cant find them. It uses basically a set of turning brakes to steer and has a small hydraulic pump driven off the engine for the blade ...... Pretty neat..... and works good. On these diffs, if you lock one axle, ALL the power goes to the other axle, with no real drag to to engine. Tractor pull tractors steer with brakes too....

Jim, I never said that it didn't work, I said that you're costing your self power. When you apply the brake to one side or the other, the differential does what it's designed to do, slowing/ stopping one side of it forces the other side to rotate faster. Depending on how big the difference is, it can be the equivalent of going from first to second or third gear for the side that is still in motion. That's where you lose your power/ mechanical advantage. You also have to remember that the spider gears in most differentials are pretty dang small, and may not live very long in this type of application if the machine is used in anger.

The reason it's not such a big issue for sand rails and pulling tractor's is because they're using the brakes for minor course corrections, not sharp turns, and they usually have power (and structure) to spare. And if you listen to the audio in the clip you linked for us, you can hear the engine lug down a bit when he turns; he just has more reserves than the guy in the ATLTF link that BM provided.

The reason I threw my idea out there is because I've seen similar designs in use; if I can ever get ahead on the cash flow side of things, that's the basic model I'm planning to start with. Besides, JRoberts has stated that he's dreaming of a machine that's KISS rule compliant.....

And if you can find those picture's, that would be great; the resolution in the video doesn't do justice for the machine...

I would have to agree in the differential steering bit

Although what u guys are calling differential isn't really

If a dozer were to simply disengage one track them it would just drive straight
They do that when we change tracks

That's why older/ smaller machines have steering brakes as well as steering clutches (my neighbor has an older Case 'dozer w/ that type of system). That's also why my mower has the brakes synchronized with the steering clutches on each side; just slipping the drive belt on one side or the other only causes a slow, gradual turn. You need the brakes to do anything tighter.

True differential steering allows u to have power to both tracks at all times
And trying to understand it is quite hard without seeing it in person
http://m.youtube.com/watch?v=A5_iNL9q18Y

Here's a short vid that brefly explains it
It is the best form of steering in a tracked machine
But is way beyond any DIY machine

I've seen that video before (thanks for posting it); I'm as guilty as the rest when referring to using the brakes to turn, letting the differential take the hit of making it work.

Pat

 

[jroberts]

To be honest, I didn't think this post would get this much attention lol and Iv'e been getting a lot of helpful ideas. Once I finish my 1st kart (hen ever I get the parts) I hope I'll be able to sell it for enough to start on the go-tank and will post it's progress. And another thing I'll need help with on it, does anyone know how to make custom airsoft guns? Cause the turret will have to be custom made.

 

[firemanjim]

Pat said..... "if the machine was used in anger"...... BWAAHAAHAAHAAHAA....

 

[porsche930dude]

i just started my tank build page. stay tuned maybe youll get some ideas
http://www.diygokarts.com/vb/showthread.php?t=24374

 

[Frostypaws12]

Yeah my shop isn't really well equipped. The "fanciest" tool I have is a china special plasma cutter running on 110v. No mills, lathes, friction stir welders etc. The press I built myself from scrap and a bottle jack several years ago to press out wheel bearings. I'm pretty sure even with just a hacksaw and welder you could still build a tank, it'll just take more time. But if time and determination is what you got, go for it!

 

[Poboy kartman]

Don`t mind it taking a long time or being hard to do. Plus easy wouldn't fun. It's just that I want to stay away from having to make bends or making my own pins cause I have no access to lathes or bending machines. Though the link that B.M. linked gave me some good ideas.

Hmmmmmm- Methinks that perhaps " The Poboy Way"- to which all are welcome in any way-( read off-topic + off-topic x2), perhaps I should start another thread called " The Poboy Club"?..????????