Quad / Crawler / ATV

Hi, I'm new on this forum and to the technology you discuss here.
I have technical/mechanical knowledge in general and understand most of what I read here

This will be my build/question/inspiration/suggestions thread

I'm building this for my girlfriend that have a spinal injury.

In the picture is a finished product of a "downhill quad bike" with 2wd hub-motors rated almost 1000w each from the manufacturer.
There is no name on the motors so have no more info, but they are planetary gears type and 36v. There's two controllers rated at 25A each.
Total weight with driver is approximately 120kg (265 lb)
More info on http://www.quadrix-team.com

We had the chance to try this quad on the trails this week and noticed right away that it's a downhill and not a uphill purpose vehicle.
It will stop very easy when driving slowly up a hill.
It uses some type of "traction control" but it feels like it limits both motors and stalls if you are driving uphill.

What I want:

I want to use this chassis but make it crawl uphill with 4wd and use hub motors (if possible?)
The rear hubs looks like conventional bicycle hub motors, front wheels are single side mounted. It also need to be reliable.
Top speed is not important because she just wants to hike with her friends. Walking phase with a little extra would be enough.

Questions:

Shouldn't it perform better or be more powerful with those 1000w geared motors?

What do you think is the best motor setup?
"Direct drive" "geared hub" "chain drive" "4-link with axles" ...

Is it possible to convert any hub motor to "single side shaft"?
Like this one http://www.ebikes.ca/shop/ebike-parts/motors/m3540ss.html

Is it enough with geared motors or will it never be able to crawl like I want?

I know there is 2wd controller setups but is there a 4wd setup? And what are your thoughts about this?

Is there a traction control that works?
That doesn't limit all motors and only the ones that spins...

I know the difference in "turns" of the motor but what is the most turns "hi torque" you get without building it yourself?

Would the MAC 12T motor be a option?
http://em3ev.com/store/index.php?route=product/product&path=50_40&product_id=207

I have probably hundreds more questions but we start here hope you guys can help us in the right direction.












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Hi. yes i was thinking of single shaft mount a MAC motor, i will send you a PM with details. thanks.

The basic problem is the target speed which is in the 5mph range. Confronted with substantial load at that speed, hub motors eat a lot of current so you need a really big controller to feed them. Heat generation is a problem.

There has been discussion here on ES in the past about similar off-road electric wheelchair projects. One was the Boma which early in its development used two big geared hub motors in the rear, but later versions switched to a single gear motor and differential. Here's the earlier one:

[youtube]QylyfA6kM9Y[/youtube]
As you can see it made the steps - but barely.

I don't really think adding two more motors running in a bad speed range is the answer unless you are really convinced that 4WD itself is of intrinsic value for application.

I would look at replacing or revising the two rear trailing arms to have a hub or other motor on an arch (or secondary chain stay contrivance) over the wheel and behind the seat a bit. Using a stock sprocket bolted up to the motor disk brake mount you could chain drive down to a conventional bicycle hub that would replace the hub motor. With this setup and a 4:1 chain reduction the elevated hub motors would be seeing effective speeds of maybe 20-25mph instead of 5mph.


A quick trip to the ebikes.ca simulator shows some results.

• using a 250rpm eZee gear motor
• retaining your present 25A controller and 36V 20Ah battery (unclear if you have one or two of these - so assuming just one)
• assuming a weight of 330lbs
• assuming a 20" wheel with 4:1 chain reduction = effective 5" wheel
• assuming an incline of 20% (as high as the simulator goes)

The bike should climb at 3.9mph on one motor - never overheat, with a range on that 20% slope of apprx 4.5mi (quite a hill).
With two motors the simulator shows about 4mph on that same hill and about the same range on the same single battery owing to the increased motor efficiency of each motor only bearing 1/2 the load (this is typical of 2WD implementations). We expect both of these (particularly the 2-motor simulation) to be able to climb much tougher inclines than 20%, but that's a limit of the simulator...

This would be the result of basically replacing the trailing arms and re-using all your present drive components (motors, controllers, batteries). Your motors are not likely to be as torquey as the eZee motors, but the results should give you some notion of what to expect with a fairly simple structural upgrade and 2WD. The existing controls, etc might remain the same. It you wanted additional power or torque, you could simply change the chain ratio or plop in bigger motors since they would be sitting in sort of elevated standard dropouts.

Using gear motors can introduce issues with the built-in freewheel clutch since reverse is usually required in these applications. It's possible to tack-weld the clutch to defeat the free-wheel effect, but the shaft key on the planetary carrier takes a bit of a beating since it wasn't intended for bi-directional forces. It's not a horrible situation, just something that you might eyeball in annual motor service. Your motors may already have a similar mod in place, so maybe not even a consideration...

Anyhow - lots of ways to go with this project - this is a way that pretty much recycles most of what you have and primarily relies on some metal fab instead of re-designing the whole drive and control system.

Nice! very good info, I also would prefer a chain drive, and with a smaller wheel I probably could fit one of these motors https://www.ebay.com/itm/201532811502 in front of the wheel and get the weight further front. But there's a balance between simplicity and over engineering
I want it to be as light as possible to...

I kinda want it to be 4wd because when we tested it, it was spinning on one side in wet grass. And as a off-road car it needs 4wd.

I could combine chain drive in the back with hub motor in the front and primary drive 2wd and when needed flip the switch for 4wd. But at the same time I want it to be as simple as possible and with chains there is a potential breakage or problems.

Mattias said:

And as a off-road car it needs 4wd. And if it's going to have drive I the front I have to either rebuild the frame and make some sort of shaft drive with cvd's etc.

Click to expand...

I would recommend against turning this into a massive Science Project instead of just getting the girl out on the trails ASAP. Look at tires etc, as standard 2WD solutions to traction issues. A simple implementation will let you evaluate your real needs and see the weaknesses of the simple approach instead of investing in a complete vehicle re-design based entirely on supposition.

If you have the time, experience, and resources, then have at it, but I think you are making this into a much more complex project than necessary.

For instance - here is a video of a non-electric 2WD quad climbing the hell out of all sorts of stuff. 4WD is nowhere to be found. Would this sort of thing make the lady happy as a first cut? Could she tolerate such a vehicle for awhile as you design and build the Ultimate 4WD Offroad Assisted Mobility Crawler?

[youtube]7TjM788JK70[/youtube]

Even assuming the mechanics of 4WD can be worked out and the existing front suspension can bear the load, the whole business of electronic control for 4WD is something that is not off-the-shelf and could take quite a while to get working properly. You could easily cheat for 2WD if you didn't like the present setup by using two throttles, but your proposal of different front/rear drive systems with different torque and speed characteristics could likely be challenging to get working well.

In the engineering world there is a saying: "Don't let the Perfect be the enemy of the Good".
(Translation: Go for a simple 85% solution rather than quadrupling the time and cost to make it 95%.)

teklektik said:

Using gear motors can introduce issues with the built-in freewheel clutch since reverse is usually required in these applications. It's possible to tack-weld the clutch to defeat the free-wheel effect, but the shaft key on the planetary carrier takes a bit of a beating since it wasn't intended for bi-directional forces. It's not a horrible situation, just something that you might eyeball in annual motor service. Your motors may already have a similar mod in place, so maybe not even a consideration...

Click to expand...

teklectic, Do you have experience doing this? I think it might be a great solution. I am working on something similar and you are right - reverse is needed. Can you recommend a hub motor to try this with? Maybe we can machine higher quality versions of the stuff that breaks? (sry to hijack thread)

skyeg3 said:

teklektik said:

...It's possible to tack-weld the clutch to defeat the free-wheel effect, but the shaft key on the planetary carrier takes a bit of a beating...

Click to expand...

...Do you have experience doing this?
Can you recommend a hub motor to try this with?

Click to expand...

Not with welding as a solution, but I have seized many clutches from overvolt, overcurrent, and impacts with a really heavy bike. As a result, I've ridden for many weeks at a time and countless miles with seized clutches, either waiting for a replacement or until I had time to do the maintenance. It's really not an issue, although as I noted, the original shaft key took a beating. That said, I replaced the original with a key hand-cut/filed from keystock to fit snugly to the keyway and never had the problem again - so the original key may have been a poor fit and just became a victim of impact stress from a sloppy fit. I've never found gear wear or noise issues running with seized clutches.

I'm running BMCs - which are siblings of MACs and eZees - the clutches and gear assemblies are actually interchangeable - there's some pictures of BMC and MAC gear clusters in my Mundo build thread. I would look at MAC or maybe eZee motors - they're big motors that can take a pretty good beating - email paul at em3ev.com or Justin at ebikes.ca. There are some teardown threads here on ES that detail the innards. Some Phaserunner controllers from ebikes.ca would be ideal to drive them - they have a nice torque throttle and a reverse switch.

When you mention geared hubs, there is always wild speculation about potential gear failures (mostly from folks who've never owned one), but that's really a rare occurrence these days on these big geared hubs. Since the manufacturers went to machined composite gears a few years back, gear melting and wear are not a consideration (well, you can always break something if you do immensely stupid things...). I have spoken with Justin about this and they seem maybe 2-3 eZee gear failures a year - again, from applying massive torque. The clutches are really the issue. I normally run 1650W through these motors and occasionally run 2000W; I always power away from standing - never pedal-start - with a 350lb gross bike weight. 13000mi and no gear failures yet. Tough little suckers.

The clutches have an internal bearing and either a roller or sprag clutch depending on the source and vintage. Laying in three short welds should present no problem as long as you are careful to compress/load the bearing to get alignment between the two clutch components. The bearing is open-race and shares the cavity with the clutch elements. As an alternative to welding, you could de-grease the clutch/bearing with brake cleaner and just shoot up the clutch/bearing cavity with 3M DP-420 Scotch-Weld Black Epoxy (stuff Doc Bass uses to attach torque arms to his frames). I have not tried that, but have no doubt that it would prove effective.

FWIW: I used to drive 2-stroke SAABs which had similar clutches (yes - a freewheeling car!). The clutchs were prone to failure from too many slamming getaways. Welding them up was a popular repair after blowing up and replacing the clutch a couple of times from too much 'WooHoo!'.

Teklektic, That sounds like it could work great. I will be trying that in the future. Thanks for the info!

The Boma All terrain is pretty awesome these days.

[youtube]kxqlbX2rrKs[/youtube]

Hi again.
Since last post I managed to buy 2 used chassis without electronics. These chassis are a bit different from the one we borrowed. They been modified to work like a manually wheelchair, they're much narrower in the back and uses single shaft wheels. I will try the simple way first with no chaindrive, if it doesn't work I try that.


I have together with MAC Motors designed 4 custom motors for this project. They will have 17mm single shaft, 16 turn, two for the front will have clutch and only used when necessary. The two in back won't have clutch and work with regen and reverse. Each with one steel gear for more reliability.

The will be delivered each with 12fet 35A infenion controllers.

I have ordered the new tattu plus 6s 22000mah with integrated BMS from Gens Ace and will run them in series for 12s
http://www.gensace.de/tattu/tattu-plus-22000mah-22-2v-25c-6s1p-lipo-battery-pack.html


I have ordered 20" fat bike wheels from https://stampedebikes.com very good service. Thanks Ian.


Now I want to order a Cycle Analyst from ebikes. I want to try running the system like it is described here, only modify it to match my setup. https://endless-sphere.com/forums/viewtopic.php?f=2&t=71073

Can someone verify that I've got the right parts. Tanks





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Hello Mattias,

Saw your build in the Youtube video you posted in the rockcrawler thread:
https://youtu.be/PLkf2F9RZQQ
Great build!
If you run into heat problems from high (phase)Amps at low speed/RPM you could benefit from cooling your hubs with Ferrofluid:
https://endless-sphere.com/forums/viewtopic.php?f=31&t=84809

There is a lot of info on cooling hub motors here:
https://endless-sphere.com/forums/viewtopic.php?f=2&t=48753

Good luck and I hope you'll update this thread with your progress and results.

Kind Regards,

SlowCo

Just looked closer at the video and reread this thread and it seems you used geared MAC motors. That's even better than direct drive hubs. And no need for cooling at all maybe? Are they 12T MAC motors? And at what voltage and current are you using them?

SlowCo said:

Just looked closer at the video and reread this thread and it seems you used geared MAC motors. That's even better than direct drive hubs. And no need for cooling at all maybe? Are they 12T MAC motors? And at what voltage and current are you using them?

Click to expand...

Glad you like it. It's custom built motors for this project with 16T. I use 2x 6s lipo batteries I series 44.4v (fully charged 50v)

I took it out today but I think battery voltage was to low and maybe the cutoff was effective because I only got around 1200w at most and max amps was 38A @ low speed and steep hill. I don't want to speculate to much about this until I charged the batteries and checked what my LV Cutoff is set at. I remember I set it high to be safe first time.

I won't have much time the next two weeks so I guess we have to wait

One thing I want to learn more about is the closed-loop modes and when to use which?
When du you want "Currant, Power or Speed mode?




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I take it you use 4 separate controllers, one for each motor? Are they all using the signal of the same (one) throttle? As long as all four wheels have traction it should work fine. I'm curious how a motor/wheel will spin when it has lost traction. If you use speed input and are gentle with the throttle it will only spin slowly. If you would use torque input I wonder if a wheel that's in the air won't speed up to top speed/rpm?

Yes, 4 controllers one throttle, I linked to a 2wd thread earlier that have a good wire diagram, I modified it a bit and I have 4 switches. 1st for Power on, 2nd for reverse and that one turns off the front motor at the same time because they would only freewheel. 3rd for 2wd/4wd and last for lights.

I also have a AUX pot meter for CA and a 3 pos switch that go directly to the front motor/esc so I can choose how much throttle/help the front wheels will give, it works great.


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Wow thats awesome, looks like a fun little beast.
Saw that youtube video, I never thought you could have such smooth control of 4 hub motors.
Well done.

TheBeastie said:

Wow thats awesome, looks like a fun little beast.
Saw that youtube video, I never thought you could have such smooth control of 4 hub motors.
Well done.

Click to expand...

Thanks! I like it a lot, can't wait to play around with it and see what it can do.

If I have to much heat problems I guess oil cooling is the easiest way to go. And because it's not fast I think it would work great and not centrifuge the oil out...

So I finally got the girl to try it a few weeks ago. This is the first time in 16 years she was able to go out in the woods like she used to do. She took it very carefully on this first run but loved it! It's still some work left to do but now I know it works good enough to finish it.

https://youtu.be/UqsTmzFeOBk

Mattias said:

So I finally got the girl to try it a few weeks ago. This is the first time in 16 years she was able to go out in the woods like she used to do. She took it very carefully on this first run but loved it! It's still some work left to do but now I know it works good enough to finish it.

https://youtu.be/UqsTmzFeOBk

Click to expand...

That is most awesome. The views remind me of the Cascade mtns of Washington state. Switching to 4 wd from the cockpit is truly amazing. Seems like it will go most anywhere..

You've made something really amazing here! Super stoked for you and your girl.

Great to see such a fantastic result. You really earned a lot of brownie points!
I see in the video you mention there is only 25% of the power going to the front. Why not more? Wouldn't it be possible for the front end to use 60-80% of the power that is going to the rear? I would think around 60% rear and 40% front power balance (of the total 100% power) would be ideal.

Great video! That thing goes like a tank.

With 4 motors, heating shouldn't be too much of an issue.

SlowCo said:

Great to see such a fantastic result. You really earned a lot of brownie points!
I see in the video you mention there is only 25% of the power going to the front. Why not more? Wouldn't it be possible for the front end to use 60-80% of the power that is going to the rear? I would think around 60% rear and 40% front power balance (of the total 100% power) would be ideal.

Click to expand...

You are absolutely right. There is a 3-pos switch on handlebar that control power to front wheels. it's set to 25/60/100% [THUMBS UP SIGN] 60% is the perfect sweet spot. Smooth and little wheelspinn.

We ride this thing almost every day and have now done 80km in rough terrain and had the first breakdown this weekend. One motoraxle was twisted off by the torque. Not very surprising when you see how she drives it [WINKING FACE]

I have ordered a pair of regular shafts for conventional dual side mounting. So next is to fabricate swingarms.

This will also open up for a wider range of motor option. I have a leaf DD 1500W motor on my e-bike that is very impressive @3kw, so much torque and motor never get hot.
They say they can make motors with max rpm down to 80. I guess a 150rpm @48v would work really good, that would give me 10 mph on 20" fat-tire with no load. But I don't know if this will work and it will be hard to sell a motor that slow... What do you guys think?

Top speed with MAC motors are now 30mph and that is not necessary.


https://youtu.be/MK-XDNhJoS0

Wow - impressive. This thing really came together. It's a bit of a hoot to see the difference between her ginger first efforts and devil-may-care bashing in the last clip.

Regardless of where the build goes from here, this is a huge quality of life success. . She's a lucky dudette to have your skills and dedication on her side.