How would you build an AATV,(amphibious 6 wheeler)?

Some controllers use a two wire pot setup, so if you use only part of the travel of a regular pot, it will work fine. Most Curtis controllers are like this.

Some controllers use a pot as a voltage divider, and need the pot to go to both ends of the range to get proper response.

I think you can program the Alltrax to work either way.
 
in a voltage divider, you have a fixed supply (usually 5v) across the pot. The voltage on the wiper then goes from zero to 5v as you turn the pot from one end to the other. The controller is really looking at the voltage, not the resistance. If the pot only turns part way, then the voltage would not reach the desired value in one direction.

In the two wire setup, the controller is really looking at the resistance. It doesn't matter how the resistance is provided.
 
Thanks for the clarification. Turns out the original throttle cable is sticking so I'll need to replace that as well. Anything special I should be looking for?
Also thinking about how to mount the motor. I was considering using the stock plate which has rubber mounting points to put some shock absorption into the system but since I'll be using chain and sprockets instead of the original belt and pulleys I think any flexing might cause mis-alignment and throw the chain off.
 
Yes, you don't want any flex in the chain alignment. An electric motor tends to vibrate a whole lot less than a single cylinder ICE, so it should be fine solid.

The throttle cable doesn't need to be anything special. I'd suggest some bicycle brake cable or something easy to find. If you're using a pot box, the cable could be quite short and the wires to the pot box can be extended. Whatever's easiest.
 
I also need to figure out my gearing. The T-20 transmission has 6:1 reduction, with final ratio to the wheels being 11:1. I'm thinking I shouldn't need too much more gearing from the motor to the T-20, and if I keep the motor and drive sprockets close enough I can swap them around for a quick gear change if I want higher speed for some reason, but mostly I need low end pulling power. Jim says he set the motor with 7.5 degree brush advancement and that the sweet spot should be between 3 and 4000 rpm. A 1.5:1 ratio would give me 16.5 final. Does that seem like enough?
 
If you measure the wheel circumference, you should be able to calculate what gearing will give you 20mph @ 3,500 rpm or whatever. Gear for the desired top speed at the motor's max rpm.
 
Looks like 16.5 will put me right around where I want to be. If I calculated it right with 22 inch tires 3000rpm gives me 11mph and 6000rpm gives 23mph. Since I'll probably be doing most of my hauling between 5 and 10mph that should keep me in the torque range. With a gear reversal I'd get a 50mph top speed, maybe :mrgreen: Not that I necessarily want to go that fast in this thing :shock:
 
The torque range could actually be the heat range, for an electric motor. I might let the gears provide the torque and keep the motor in the high efficiency range... your power will go into work, rather than heat.

You should still have the option of flipping gears for higher speed, but even 23mph seems exciting.

:D
 
I still think I'm on the high side in regards to RPM's with this motor. Jim said he's had one of these Yales in a go kart geared for 35mph at only 1900RPM on 48 volts and the motor handled it no problem. I don't want to gear too low because I'll still need some tire speed to get through mud and water.
 
1900rpm in a kart might not be drawing the current required for hauling. It's the current that generates the heat. As the motor rpm approaches no-load speed, the current declines and efficiency rises, providing more power at the gears.

At the very least, you might want to keep enough adjustment available in the setup to allow convenient swapout of gears.

HTH
 
I am prepared to do some adjusting since I'm learning as I go. Today I just realized I won't be able to swap gears between the motor and T-20 since they have different shaft sizes :shock: Oops. Not a big deal deal I guess.
Taking another look at the Gorilla, http://www.gorillavehicles.com/GorillaSpecifications.htm, they use 14.5:1 gearing at 24 and 36 volts with 20 inch tires giving them 19mph top speed with the 36 volt setup. I'm assuming I'll draw less current with a 48 volt setup? I'm not sure what motor they use.
 
It's hard to say what you amps can pull constantly, without knowing the rated load for the motor. Jim should have a spec for that. Exceeding the rating can be done briefly (or longer with cooling). Burning up out in the woods would totally suck.
 
My mind wandered back to the 2 motor concept, one for each side, and removing the transmission. I'm not doing this but was working it through in my head. Since the steering is by locking up one side of the transmission and driving the other it seems to me it would be really hard on the motors. You'd essentially have to stall the motor by slightly reversing it while turning, drawing huge currents, right? Plus the control issue would be difficult, you'd have to have 2 throttles and 2 controllers so you could throttle up the driving wheels while applying some throttle to the stalled/reversed side.
 
Actually a two motor steering setup would work fine. It's how most electric wheelchairs work. You would need two motors and two controllers and some interfacing electronics, so the cost will zoom. With the right controller setup, you wouldn't even need to use the brakes, the motors would do it. I could imagine a "really hopped up" wheelchair controller. You could drive the ATV with a little tiny joystick.

I suppose if you used two motors in series with one controller and used the brakes to hold one side, that might work without being too hard on the motors. When one motor stalls (gets the brakes), all the power will shift to the other motor. This only works if the motors are in series, which means you need double the voltge to run them.

A simpler option would be to put two motors and two controllers in parallel, to keep the battery voltage the same, but have a cutout switch tied to the brake levers to kill the motor when you hit the brake on that side. You would still need two controllers and two motors.
 
fechter said:
Actually a two motor steering setup would work fine. It's how most electric wheelchairs work. You would need two motors and two controllers and some interfacing electronics, so the cost will zoom. With the right controller setup, you wouldn't even need to use the brakes, the motors would do it.
Click to expand...
Do you know how they electronically stop the one side without a huge current draw? Or is a wheelchair so light it's not that much of a problem? If you just stopped power to one side it would still freewheel wouldn't it?
I could imagine a "really hopped up" wheelchair controller. You could drive the ATV with a little tiny joystick.
Click to expand...
chair_features.gif

:mrgreen: My ultimate dream 6x6 would be six hub motors, full suspension, and joystick control.

A simpler option would be to put two motors and two controllers in parallel, to keep the battery voltage the same, but have a cutout switch tied to the brake levers to kill the motor when you hit the brake on that side. You would still need two controllers and two motors.
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That's probably the most practical way to do it. The steering brakes are inside the T-20 transmission, but there are two disc brakes on the front axles which could be hooked up independently to allow steering when the T-20 is removed.
 
JRP3 said:
Do you know how they electronically stop the one side without a huge current draw? Or is a wheelchair so light it's not that much of a problem? If you just stopped power to one side it would still freewheel wouldn't it?
Click to expand...

I think most of them use regenerative braking so while there would be lots of current in the motor, there wouldn't be any extra drain on the batteries. This also gives a very smooth steering action. Most of them can also reverse each side independently, so you can spin on your own axis. If you actually got a wheelchair controller with the joystick, it might be possible to interface a pair of much larger controllers / relays to handle bigger motors.

I'm not sure if the motors you're planning to use can do regen though. Are those series wound or sep-ex?
 
fechter said:
I'm not sure if the motors you're planning to use can do regen though. Are those series wound or sep-ex?
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Well I'm talking pure fantasy at this point but yes my dream machine would have re-gen capable hub motors, along with EESTOR caps, a carbon fiber body, and the ability to levitate :mrgreen:

The one I'm actually building has a single series motor :cry:
 
JRP3 said:
fechter said:
I'm not sure if the motors you're planning to use can do regen though. Are those series wound or sep-ex?
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Well I'm talking pure fantasy at this point but yes my dream machine would have re-gen capable hub motors, along with EESTOR caps, a carbon fiber body, and the ability to levitate :mrgreen:

The one I'm actually building has a single series motor :cry:
Click to expand...

Flying car? Let me work on that unfinished inertial motor in the back of my closet :p.
 
I am curious as to how much the regen would work at the speed you will be going. I do think the amps required to electrical throw a motor into reverse will be quite high on your vehicle as compared to a Wheel chair. The wheelchairs are A) Going much slower and B) have a freewheeling castor wheels, whereas the 6 wheeler is tearing up the ground to do a 360.

How about something more like the zero radius turn lawnmowers. I think, the engine drives a hydraulic pump and then each wheel is a reversible hydraulic motor.
 
drewjet said:
I am curious as to how much the regen would work at the speed you will be going. I do think the amps required to electrical throw a motor into reverse will be quite high on your vehicle as compared to a Wheel chair. The wheelchairs are A) Going much slower and B) have a freewheeling castor wheels, whereas the 6 wheeler is tearing up the ground to do a 360.
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True but in the 6 hub motor version of my dreams the load is divided by 3 motors on each side so it might not be too bad.
How about something more like the zero radius turn lawnmowers. I think, the engine drives a hydraulic pump and then each wheel is a reversible hydraulic motor.
Click to expand...
In that case instead of adding hydraulics I'm better off just keeping the existing T-20 trans , which can actually be shifted into reverse on one side while the other is going forward if you change the single reverse lever into 2 separate ones. I may actually do that mod on my single motor setup if I feel the need. Since the T-20 is essentially 2 transmissions sandwiched together they don't always sync up when shifting from fwd to reverse with the single lever setup and you have to rock the machine back and forth to get it to engage.
 
A little update. Progress is being made, slowly. Still struggling with the throttle setup though. At least I now know exactly what I want:
http://www.electricvehiclesusa.com/product_p/th-bz31686.htm
This way there is no throttle cable to wear out or freeze up, (my old one did that in the winter, very annoying), just an electrical connection from the throttle to the motor.
Problem is they no longer have that throttle and the one other place I've found that does have it wants $37 plus $11.46 shipping.
I can probably make my own but I would definitely need a strong pot since I'd be grabbing the lever attached to it.

I just picked up 2 battery chargers on ebay, a Protech4 20amp and a Protech4 30, $105 each plus shipping. They can each handle 3 batteries so I'm covered if I ever go up to 72 volts. Got them from this guy who seems to have some good deals:
http://stores.ebay.com/The-ChargerG...o=CRX&its=S%2BI%2BSS&itu=ISS%2BUCI%2BSI&otn=4

Motor mounts are almost finished, I need to make some slotted holes so I can slide the motor back and forth for chain adjustments. Right now I'm fighting with a broken tap that snapped off in one of the holes I was trying to thread, and nothing seems to be able to drill through it :evil:
 
You can vaporize it:

http://weldingweb.com/showthread.php?t=14553&highlight=oxy+broken+tap

yorkiepap said:
You simply use O/A, using a small (1-1.5"), high oxy. flame and get the tip of the inner flame cone to touch the broken object and hold it until the object is almost white, and then quickly turn off the acetylene while holding the torch in place and the oxy. will feed the molten puddle and literally disintegrate the tap or screw.
Click to expand...

:shock:
 
JRP3 said:
Motor mounts are almost finished, I need to make some slotted holes so I can slide the motor back and forth for chain adjustments. Right now I'm fighting with a broken tap that snapped off in one of the holes I was trying to thread, and nothing seems to be able to drill through it :evil:
Click to expand...

I hate it when that happens. If the hole is big enough, sometimes you can shatter what's left of the broken tap by beating on it with a center punch. Otherwise, I've used a diamond burr mounted in a Dremel grinder. Very slow, but eats through anything.

I wonder if you could use a hall effect thumb throttle? Those are much easier to find. It would depend on the controller.
 
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