# Mini tank/dozer



## aodshocky (Jan 19, 2014)

I have this idea for a mini tank/dozer. It would be tracked and each track would be independently driven by its own motor and possibly it's own controller. Can I take 48 volts and feed two controllers to drive the motors that way my batteries drain equally?
Is there a single controller that can control two motors seperately from each other so one can move faster or in reverse from other(steering)? What kind of batteries should I be looking for to give me two or three hours of run time max?

Thanks

I have matching motors to pull from a forklift Saturday. Controller too if it will work with this idea.


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## frodus (Apr 12, 2008)

Gonna need two controllers.

If those matching motors are Series wound, you'll have a weird control scheme. Series wound controllers need to use reversing contactors, so they switch back and forth every time you switch direction. This shouldn't be done under load (limits life of the contactor by a lot), so you'll have a very jerky forward and reverse direction change.

I'd consider either Sepex motors, or PM DC if you want to keep cost down.

What do you imagine the weight to be? top speed?


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## aodshocky (Jan 19, 2014)

Is all I have for info right now. 
Is there an easy way to check? On label?


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## frodus (Apr 12, 2008)

I can't see what that is (blocked). Can you attach the picture instead?


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## aodshocky (Jan 19, 2014)

http://i224.photobucket.com/albums/...B-C468-4E68-BE33-4B2B70870432_zpst835jpw4.jpg
Try this??


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## frodus (Apr 12, 2008)

Its blocked where I'm at, i.e. photobucket is blocked. 

If its got 4 terminals labeled something like S1, S2, A1, A2 its a series wound. If they're labeled F1/F2 then its likely sepex.


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## aodshocky (Jan 19, 2014)

I only see two terminals.


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## frodus (Apr 12, 2008)

Series wound most likely. Not great for forward and reverse tracked drive.... IMHO


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## aodshocky (Jan 19, 2014)

Figures I get two matching motors and I might not be able to use them. I'll still pull them. Might have a use for them some day.


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## aodshocky (Jan 19, 2014)

i attached the picture as an attachment. if you look it only has two posts. does it look like a series?


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## aodshocky (Jan 19, 2014)

frodus said:


> What do you imagine the weight to be? top speed?


I am not sure yet on weight yet. it would be at best guess i would put it in a range of 600-1000 pounds and I would want a top speed around 5-8 mph. I am thinking more torqe than speed anyways. its going to be ment to move stuff.


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## aodshocky (Jan 19, 2014)

ok i got the two motors out. they have four posts on them s1 s2 a1 a2. (series?)

attaching pics


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## major (Apr 4, 2008)

aodshocky said:


> ok i got the two motors out. they have four posts on them s1 s2 a1 a2. (series?)
> 
> attaching pics


Yes, series wound. Looks like old Prestolite 6.6" dia motors. Appear to be in good shape.


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## aodshocky (Jan 19, 2014)

they are in really good shape, the other one looks even better than this one. as series wound that would meen that i need a contactor to reverse them correct?
i also can not seem to find much info about them as in volts and any other information. all i get from clarck 2750371 is drive motor and thats it.


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## aodshocky (Jan 19, 2014)

my next step is to find controllers for the two motors. so i need one each. 

i also need contactors? one each for foward and reverse or do they have a single unit that has both direcetions in it? (per motor)

a throttle I am thinking Merritt Pro4 or something similar. (I was originaly thinking of using pc joysticks but i am unsure if they would be compatible)

and batteries.

am I missing anything else for electronics?


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## aodshocky (Jan 19, 2014)

So all I can find out is 24v on these motors. What other info do I need about them? I am in contact with a company and right now all they will tell me is what I know and that's the volts.


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## major (Apr 4, 2008)

aodshocky said:


> So all I can find out is 24v on these motors. What other info do I need about them? I am in contact with a company and right now all they will tell me is what I know and that's the volts.


They are private branded special designed for Clark forklifts and not for general commercial consumption. The company does not care about you or spending any time with you unless you want to buy a new forklift.

You can apply these salvaged fork motors to your EV project just as many do here on the DIY. See the sticky thread on the subject. From that and other build threads and EVAlbum you should find what you need to know.


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## aodshocky (Jan 19, 2014)

All right. Thanks  working on finding affordable controllers now.

I'm also thinking about Curtis 1207B


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## frodus (Apr 12, 2008)

You'll need two forward reverse contactors (they're specific for forward/reverse application), one for each motor/controller and also a standard contactor (one should be fine).

Its going to be clunky when you try to drive in tank drive mode. I'd suggest not trying to do 0-degree turns with it unless you're stopped, or it will jerk the vehicle around. 

Why?

On series wound controllers, they don't go in reverse, just 0-100% in forward, so that is one issue.

Also, series wound motors don't care about the polarity of the power coming into the motor. If you switch the polarity of the motor cables, you still rotate the same direction. To get reverse on a series wound motor, you have to reverse the armature and field windings from eachother. 

Lets say you wire it as Motor+ on the controller to S1, S2 wired to A1 and A2 wired to Motor- on the controller. To go reverse, you need to wire as Motor+ going to S1, S22 wired to A2 and A1 wired to Motor-. You're switching the direction of current in the armature (A1, A2) so its opposite of what goes through the Field (S1, S2). So you need a contactor that simultaniously disconnects S1 and S2 and swaps them.

So if you're driving, you'll be going forward, then you have to come to 0% throttle, flick a switch to reverse, then increase throttle to go the other direction.

Its just not going to be as smooth as a reversable motor and controller. Just making sure you know this.

Now if you drive in half-tank mode, where you just stop one motor but still drive the other motor to turn, it will work just fine. Also, at a stop you'll turn just fine. Its the transitions between forward and reverse that will be clunky.


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## major (Apr 4, 2008)

frodus said:


> Its the transitions between forward and reverse that will be clunky.


Forklifts can plug reverse smoothly with series motors without clunking  It could be done on a track steer system but you'd have to have suitable controllers and good tuning. 

You'd think that if those motors can propel a 3 or 4 ton fork truck with 24V, they'd handle his little tank/dozer. I wonder why he just doesn't just use the fork traction control system as is.


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## aodshocky (Jan 19, 2014)

As for turning I figured zero turns from complete stops anyways. Gradual turns controlling faster/slower depending l/r direction. 

I do not know if I can separate the left/right motors. The donor truck was three wheel. Rear single wheel for steering while both fronts drive it. If I can use that I'm all for that and save myself some money.


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## aodshocky (Jan 19, 2014)

If this helps this is what I see under the "hood"


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## aodshocky (Jan 19, 2014)

so i pulled a couple of the contactors off of that jumble of wires and brought them home. my intention was to find out more about them. what i found out was that entire jumble of wires and contactors was the entire motor controller. the only problem i have now is in the process i unhooked a bunch of wires and stuff from the contactors and i am not confident enough to put them back. 

also from what i can see it would not work for what i have invisioned. i need to be able to controll each motor independantly from each other that way i can slow one side down to turn.


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## frodus (Apr 12, 2008)

Got more shots of that contactor? It looks similar to a reversing contactor.


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## aodshocky (Jan 19, 2014)

here are the other three pictures i took of the contactor removed from the truck.


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## frodus (Apr 12, 2008)

While the label helps, I was speaking about the actual contacts, maybe a top, front, back, side shot? 

It looks like a part of a reversing contactor, but I'm not sure. You should google the part number.

Also, you'll need a controller, it looks like that is all from an EV-1 SCR controller.


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## aodshocky (Jan 19, 2014)

I'll get better pics in a bit.


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## aodshocky (Jan 19, 2014)

Side view. Upper is connected. When power applied connects lower.


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## aodshocky (Jan 19, 2014)

this is a very rough 1/3 scale model of what i have in mind. these two pics show the tracks and electronics bay area. ill have enough room for the duel motors, 4 12v batteries, controllers and contactors. I plan to have it sealed to the weather with a solid platform directly above the tracks for seating, throttles and any gages i will need.


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## Woodsmith (Jun 5, 2008)

It would have been so tempting to have just pulled the whole front axle assembly from the forklift.

That would give you the two motors, reduction gearboxes, drive wheels and a frame to carry it all.
The drive wheels could then be removed and converted to drive sprockets for the tracks and it would have the right sort of road speed and super strong components within the drive train.

I almost went that route, for my tractor, with a similar forklift I found at the scrap yard but the guy sold it whole to someone else.

You could also have had the hydraulic system so your tank can also 'do stuff'.

In fact, go back and buy the rest of the forklift, now!


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## aodshocky (Jan 19, 2014)

If I had the room I would have.


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## frodus (Apr 12, 2008)

Can you get a top view? I can't really see all of the contacts. It looks like a reversing contactor, but until you get a shot with all of the contacts showing, I can't say for sure.


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## aodshocky (Jan 19, 2014)

How is this?


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## puddleglum (Oct 22, 2008)

Woodsmith said:


> In fact, go back and buy the rest of the forklift, now!


If the owner of the forklift will let you pick it clean, Seriously, go back and get as much as you can, even if you can't take it all. Woodsmith is right, you can use a lot of the forklift parts for this I think. That doesn't look like the reversing contactor. They are usually a double contactor.


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## aodshocky (Jan 19, 2014)

puddleglum said:


> If the owner of the forklift will let you pick it clean, Seriously, go back and get as much as you can, even if you can't take it all. Woodsmith is right, you can use a lot of the forklift parts for this I think. That doesn't look like the reversing contactor. They are usually a double contactor.


They pretty much said i can help myself. i am going to take the rest of the ev-1(?) controller, I am pulling all the power cables, I want to take off the pump motor but can’t find the bolts yet. I am not sure if i will mess with too much of the hydraulics yet. I know the main cylinder has a massive leak and they didn’t want to pay to fix it, and it is destined to the junkyard. i should grab the f/n/r switch and throttle pedal.


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## puddleglum (Oct 22, 2008)

If you can get the tilt cylinders, control valve and pump along with the pump motor, you'll about have everything to do the dozer. All those parts are fairly small, and if you get the electric parts as well, this could be a really cheap build. steering is going to be the hard part though as frodus said.


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## aodshocky (Jan 19, 2014)

puddleglum said:


> If you can get the tilt cylinders, control valve and pump along with the pump motor, you'll about have everything to do the dozer. All those parts are fairly small, and if you get the electric parts as well, this could be a really cheap build. steering is going to be the hard part though as frodus said.


as long as i can control the speeds of each side my stearing should not be to much of an issue. like said to do teh zero turns i would come to a complete stop before reversing one of the motors.

as for the contactors, should I try to use them? they appear to be in a always on to the upper and when the coil is activated it pulls to a lower. could i use that as a forward/reverse contactor?


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## puddleglum (Oct 22, 2008)

I was thinking that steering could be an issue if you use the forklift controller since I don't think it has individual control for each motor. If you use a couple of small controllers it won't be a problem. The contactor you have doesn't look like the fwd./rev. contactor to me. They are usually a double contactor (two contactors side by side with a long bussbar between them). If you go with two controllers and you stick with 24 volts, you could use the ones on the forklift for one side but you will need another set for the second controller. The single ones are for line and pump contactors. Curtis has some pretty good diagrams of how to set it up and the path of power through the contactors.

Are you going to use two control levers? If you use the smaller Curtis controllers, most of them are designed to plug so reversing will be easy. You just need a microswitch to activate for each direction and a way to control your pot.


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## aodshocky (Jan 19, 2014)

Yes the idea was to get two controllers , one for each motor. 
I was thinking of the Curtis 1207b, Merritt pro 4 for throttles. 
I have four of these contactors that originally looked like the following.


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## frodus (Apr 12, 2008)

That throttle is a forward reverse throttle meant for a controller that does forward and reverse. Your controllers will only go forward, with a switch controlling the forward reverse contactor.


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## aodshocky (Jan 19, 2014)

I figured the pro 4 because if this description

Configuration: Joystick with knob handle. Spring return to center (off) position. 5 k ohm 4-terminal pot controlling inboth forward and reverse. Detent at neutral/center position. Microswitches for driving forward and reverse contactor coils are automatically activated away from center position. 

http://www.kta-ev.com/Merritt_Joystick_Pro4_Throttle_w_Center_Return_Spr_p/pro4-101.7098qs.htm
From that site.


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## frodus (Apr 12, 2008)

The 1207 drives the f/r contactor. You WILL absolutely need a programmer to set these up.

Page 14:
http://www.fsip.biz/Documents/1207_7A.pdf

forward reverse throttle. You'll need to figure out the pinout for it, but the Pro4 should do the same thing.


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## aodshocky (Jan 19, 2014)

Ok I will poke around with the pro 4 later on. I want to play with thes contactors for a bit. Trying to figure out how they worked in the forklift.


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## aodshocky (Jan 19, 2014)

Frodus do you have a reversing contactor that is wired up? If so could I see a pic or two?


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## frodus (Apr 12, 2008)

google "reversing contactor"

I don't use them because all of the drives I work with are AC or BLDC and are reversable without a reversing contactor.

Also, Read the manual! It goes over exactly how it is all wired.


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## aodshocky (Jan 19, 2014)

Google hasn't helped much for images I'll find a manual for one and do that. Thanks.


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## frodus (Apr 12, 2008)

Hasn't helped at all? http://lmgtfy.com/?q=EV+%22reversing+contactor%22

I think you already have reversing contactors, but you took them apart from the backplane. There were several contactors. One was likely reverse, the other likely forward. They'd be bussed together.

http://www.diyelectriccar.com/forums/attachment.php?attachmentid=18087&d=1392743480

There are two, maybe three in that picture.


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## aodshocky (Jan 19, 2014)

That first link. Way cool. My mistake was not adding "ev" to my search. 
There are four contactors in that line. They are paired together at the to as seen in the pics. (I saved all parts and put them back into pairs) but there was a bar connecting them all as well. I'll get pics later tonight when I get home.


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## puddleglum (Oct 22, 2008)

I have to apologize as I was in error in my previous comments. I pulled up the parts list and the wiring diagram for the forklift after work today and it looks like the 4 contactors that are connected with the long bussbar are the fwd/rev contactors. They just look different than the ones I'm used to seeing. There is a set for each motor so you won't need to buy any more if you stay with 24 volts. There are also 1A and pump contactors on the panel which you could use for line contactors I think. I tried to save the manual for you but the program won't let me. I may be able to copy and scan the diagram of the heavy wiring if you think it will help you figure out how to wire them back up.


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## aodshocky (Jan 19, 2014)

puddleglum said:


> I have to apologize as I was in error in my previous comments. I pulled up the parts list and the wiring diagram for the forklift after work today and it looks like the 4 contactors that are connected with the long bussbar are the fwd/rev contactors. They just look different than the ones I'm used to seeing. There is a set for each motor so you won't need to buy any more if you stay with 24 volts. There are also 1A and pump contactors on the panel which you could use for line contactors I think. I tried to save the manual for you but the program won't let me. I may be able to copy and scan the diagram of the heavy wiring if you think it will help you figure out how to wire them back up.


that is cool, i have tried to find info on the parts, I have found the pump contactor and plan on takeing that out soon. i think i know where the 1A one is. 
I have been trying to figure out how they work as reversing and the wireing diagram might help me. for some reason i can not understand why the four contactors were connected by the larger bar at the bottom. 
good news if i can use them for my reversing contactors though.


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## aodshocky (Jan 19, 2014)

i found this image online, this seems to help me understand the reversing contactors better. the image is blurry making hard to read some of it but i think i understand it better now.

working with that image i belive that i can make mine work. the original setup had the lower tabs in the 2nd picture connected as well so I think I have to do that too.

the third pic also shows the oppisite side.

unless im wrong


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## puddleglum (Oct 22, 2008)

Glad you understand it now. The diagram you found is much easier to follow than the Clark one anyway. You will have a better time following it. I only had a couple of minutes to look at the Clark diagram, but I think the long bar connecting all the lower terminals was M- on your diagram and the one controller controlled both motors. EV1 is a pretty complex setup so the schematic is harder to follow and I am not very familiar with it .


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## aodshocky (Jan 19, 2014)

I was bored today so I weighed in my motors. 40 pounds each. Taking a break from my contactors while looking for some controllers. Might have found some on ebay. Will see how it goes.


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## aodshocky (Jan 19, 2014)

not sure about the ebay controllers now. I however talked to our forklift repair company man and he said he would check with another company that has a crapload of broken power jacks and try to get me a couple controllers.


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## aodshocky (Jan 19, 2014)

Thinking about the battery setup. I was thinking 4 12 volt batteries basically two for each side. To get equal drain would I have to make 2 sets series and then parallel them together?

If that is the incorrect thinking what would be the correct way to set it up so 4 batteries will drive two controllers?


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## aodshocky (Jan 19, 2014)

I think I have the wiring figured out. What do you guys think?


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## aodshocky (Jan 19, 2014)

i need some help, i have managed to remove the gears from my motors and found something i was not expecting. the shafts are spline. how do i measure the splines so i can find sprockets or pulleys that will fit? attached is a picture of the gear that came off. it has 13 splines.


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## puddleglum (Oct 22, 2008)

aodshocky said:


> i need some help, how do i measure the splines so i can find sprocket? it has 13 splines.


I think you just need to know O.D. of the splined shaft and the number of splines. Check with a driveline shop or possibly an Hydraulics shop. You should be able to find internally splined couplers or sleeves that you can weld into whatever sprocket you want.


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## JRP3 (Mar 7, 2008)

Or just use the splines you have and weld or machine them to fit whatever pulleys you want to use.


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## aodshocky (Jan 19, 2014)

JRP3 said:


> Or just use the splines you have and weld or machine them to fit whatever pulleys you want to use.


That has crossed my mined too. I am currently focused in finding the tracks. I also need to get with my nephew and go over the metal work. Figure out how much I need. I am hoping soon to start adding build info to this thread


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## aodshocky (Jan 19, 2014)

i picked up a few more parts off the fork lift today.
motor/pump, wires, forward/reverse lever, seat and hydraulic levers.


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## aodshocky (Jan 19, 2014)

So I did a wood build to verify my dimensions last week. I sat on it and it was comfortable. I had nobody to take a pic of me on it. I need to get it home and check motor fit but it looks like they will fit as planned. The piece of board on top is 48 inches long by 39 wide. The tracks measured just over 52 inches front to back. Well within my planed size.


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## Haggerty (Jun 9, 2010)

Scaledtanks.com might be of use for you, they have pretty detailed plans on creating 2/5 scale tanks as well as tracks.


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## aodshocky (Jan 19, 2014)

Haggerty said:


> Scaledtanks.com might be of use for you, they have pretty detailed plans on creating 2/5 scale tanks as well as tracks.


actually im a member over at that site too. the scaled tanks they have made are really cool.


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## aodshocky (Jan 19, 2014)

wow i cant believe how this project stalled. It is now September and I am trying to revive it. 


Bulldozer sub-projects.1. Replace gear with pulleya. Find pulley with matching spline
b. Remove teeth from gear, add pulley hub

c. Keep gear, find larger matching gear to drive pulley 
​2. Tracks.a. Custom build tracks from old conveyer belt material(www.scaledtanks.com)
b. Use snow mobile tracks split in half​3. Motor controllers (buy)
4. track wheels and drive sprocket (fabrication)
5. track frames (fabrication)
6. body (fabrication)
7. batteries (buy)
8. throttles (buy)
9. motor mounting (fabrication)
10. charging system
11. mounting snow plowa. manual operation(as it is now)
b. convert to hydraulics(using pump and parts from donor forklift)​


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## evBEDNER (Sep 14, 2014)

one of my neighbors made a set of tank tracks by using tire tread with the sidewalls removed. joining the ends was the hard part .. i think he used large steel staples of some sort


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## aodshocky (Jan 19, 2014)

I finally have info on my motors that should help. 


14 tooth spline, free load 12v, 38 amps, 3,000rpm, light load 24V 80 amps 3500-3900 rpm


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## aodshocky (Jan 19, 2014)

so now that i have moved twice since i have started planing this project i will now rededicate the parts to making a 2/5 scale tank. I am not sure if i will base it on a real tank (past, present or future) or just make up my own design.

more info to come in the next weeks or so.


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