Has anyone tried using a differential?

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Slistack   10 mW

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Has anyone tried using a differential?

Post by Slistack » Sep 23 2014 2:14am

Hi, I am new to the EV thing, I was wondering if anyone has ever seen anyone using a differential with one motor to power two wheels on a longboard? Also what is the best system in an ideal world to power a longboard, Direct drive, belt drive, Differential if it was possible? I want to build a longboard and am willing to take input.

rutierut   1 mW

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Re: Has anyone tried using a differential?

Post by rutierut » Sep 23 2014 3:08am

I once looked into it but it was simply to difficult, if you have acces to welding equipment and something like an CNC machine i guess it would be worth a try. It would look cool tough

Slistack   10 mW

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Re: Has anyone tried using a differential?

Post by Slistack » Sep 23 2014 12:51pm

So you are saying you have never seen it before? Cool I have devolped a way to do it and have been wondering if anyone has done it before. do you think people would be interested in seeing some pictures?

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LEVer   10 kW

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Re: Has anyone tried using a differential?

Post by LEVer » Sep 23 2014 2:25pm

Pics...or it didn't happen. :D

Slistack   10 mW

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Re: Has anyone tried using a differential?

Post by Slistack » Sep 23 2014 3:31pm

Well here is a teaser, this is my version 1. Let me know what you think. Feel free to ask questions.

20131204_004731.jpg
Mach 1
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torqueboards   100 MW

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Re: Has anyone tried using a differential?

Post by torqueboards » Sep 23 2014 3:38pm

Slistack wrote:Well here is a teaser, this is my version 1. Let me know what you think. Feel free to ask questions.

20131204_004731.jpg
How does it work? I would think they would be better sensored than not.
DIYElectricSkateboard.com Electric Skateboard Kits

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LEVer   10 kW

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Re: Has anyone tried using a differential?

Post by LEVer » Sep 23 2014 4:37pm

So is this like a 1/5 baja differential? I think this would be great so you could mount a motor and not worry about the deck hitting it.

Although, as torqueboards touched on, you may need a sensored setup AND a bigger motor. May add to the weight too.

BTW, two motors setup per wheel per axle has electronic differential.

rs4race   100 W

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Re: Has anyone tried using a differential?

Post by rs4race » Sep 23 2014 5:52pm

I was looking into it as I want to do it. I found a nice pdf on gear strength calculations, including bevel gears. I haven't had a chance to run the numbers yet.

I think two motors are just right for a board, so one motor front and one back with awd would be really nice. Any pics how you have the gearing setup?

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LEVer   10 kW

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Re: Has anyone tried using a differential?

Post by LEVer » Sep 23 2014 6:02pm

^^^ FTW!

Slistack   10 mW

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Re: Has anyone tried using a differential?

Post by Slistack » Sep 23 2014 6:42pm

it is a 1/8 scale truggy? Differential, also that motor was WAYYY to big for anyone. I fell off of it 2 times cause it had way too much torque. I had to replace a differential after about six months of abuse IE not current limited controller. I really don't think you need 4wd. I made this in September last year and used it in the winter and it was fine. I have been looking for better wheels and I found some i just cant buy them. I have never riden a long board before, so I have no idea what longboarders think of. But when I made this I made it as a pure engineering test. It turned really crappy but it would throw you up a hill at 20mph and didn't complain. I have now moved to a 6354 sk3 motor and I think that is even a little to powerful. Also I have had sensors installed makes a HUGE difference at low speed and in efficiency. When I built this one I had no idea if it would work or not but guess what it does. On this one i literally have a floating differential in its stock case I didn't change any gearing. I don't like electronic differentials too messy two speed controllers and all. I am a mechanical guy not a electrical guy, I dabble but twice as much to deal with no thanks. In my version 3 I am using a 1/8th scale race car differential.

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onloop   10 kW

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Re: Has anyone tried using a differential?

Post by onloop » Sep 24 2014 7:09pm

Definitely thought about this for hours....

I think it is worth testing. But the cost of the diff needs to be less than the cost of buying that extra 1x motor. 1x. Motor mount 1x ESC. To setup a dual drive (two motor) eboard. & if the diff is cheaper than adding the 2ND motor the performance when using a diff needs to be equal or better then the two motor drive.

Otherwise it's not worth it.

Also there is a mechanical loss that needs to be considered.

Also there is a weight factor to be considered.

Also a maintenance schedule for replacing different oil etc.

My conclusion was it's too expensive for no real gains.
Last edited by onloop on Sep 25 2014 12:00am, edited 1 time in total.

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fechter   100 GW

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Re: Has anyone tried using a differential?

Post by fechter » Sep 24 2014 7:33pm

Two motors will probably survive longer. If each motor has its own ESC, it should work much like a differential. With brushless motors it's not possible to run two motors off a single controller.
"One test is worth a thousand opinions"

Slistack   10 mW

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Re: Has anyone tried using a differential?

Post by Slistack » Sep 25 2014 3:49am

Its like 20 dollars for the diff, and another 60 dollars for another motor and another 60-80 bucks for another speed controller. You will lose the efficiency in your motor controllers more than the gears. so you are looking at another 120 at least in additional electrical components. I think that these crappy Chinese car esc's are not as efficient as you would think. I should know i've blown up at least 4 really nice car and plane esc's. I think its more elegant and put together. I think that the differential will last as long as the battery with the proper speed controller so that it doesn't strip the gear's which is what happens when you apply way to much power. I hope to be making a product someday soon. I hope it will change what people do with long boards. I mean most people just don't have cnc milling machines and beautiful lathe's in their basement. Gears have really good efficiency while belts tend to lose some energy. I don't have all the answers but I am looking for maximum efficiency. right now I am getting about 12wh/mile. Which is pretty darn good but I can increase by at least 20% with some cleverness.

rs4race   100 W

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Re: Has anyone tried using a differential?

Post by rs4race » Sep 26 2014 8:42am

The only way your going to reduce efficiency with a diff is if your just turning circle the whole time. The bevel gears are stationary in a straight line. Generally a larger higher up motor is more efficient than two smaller equalling the same hp, plus one less set of pulleys or gears to loose power on. It has potential.

Slistack   10 mW

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Re: Has anyone tried using a differential?

Post by Slistack » Sep 26 2014 2:40pm

I am currently on my version 3 board and might finish this week. There are tight tolerances and i screw up, haha. Anyway I will post pictures when i am done but I hope to make something out of it but if nothing comes of it, it will be my last build.

Barndom   10 W

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Re: Has anyone tried using a differential?

Post by Barndom » Sep 29 2014 5:18am

I like it! Would be interesting to see how it is mounted on the board. This is a similar one, don't know if it has i differential thou.
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onloop   10 kW

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Re: Has anyone tried using a differential?

Post by onloop » Sep 30 2014 3:27pm

$20 diff... that seems too cheap. How do you make it?

Slistack   10 mW

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Re: Has anyone tried using a differential?

Post by Slistack » Sep 30 2014 10:46pm

you dont make it you buy it from a company that makes 1:8 scale cars.

Hummina Shadeeba   1 MW

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Re: Has anyone tried using a differential?

Post by Hummina Shadeeba » Oct 01 2014 1:10am

How bout a link for us? Show us a pic of the one for sale.

I though a belt was more efficient than mechanical diff with a 90 degree angle and teeth.

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onloop   10 kW

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Re: Has anyone tried using a differential?

Post by onloop » Oct 01 2014 4:53am

really you can buy a full functional diff for $20?

> Does that include the axles & differential gears, what about the pinion shaft & gear? is it enclosed, What's it made from?

Honestly it sounds to good to be true.

rs4race   100 W

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Re: Has anyone tried using a differential?

Post by rs4race » Oct 01 2014 3:02pm

Generally its just the carrier with spiders.

Slistack   10 mW

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Re: Has anyone tried using a differential?

Post by Slistack » Oct 05 2014 11:59am

all it is is the differential, and the differential is more efficient then a belt drive, probably like 10% or more.


http://www.ebay.com/itm/HPI-Trophy-Bugg ... 56691a41e4

Slistack   10 mW

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Re: Has anyone tried using a differential?

Post by Slistack » Oct 05 2014 12:07pm

This is for scale the differential in the middle is the one in the link and also those are 90mm wheels.

Image

Slistack   10 mW

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Re: Has anyone tried using a differential?

Post by Slistack » Oct 05 2014 12:08pm


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LEVer   10 kW

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Re: Has anyone tried using a differential?

Post by LEVer » Oct 05 2014 4:17pm

Slistack, I'm very interested in this as it allows me to use a single long and powerful motor to drive both wheels, put it under the board and still have a differential system. My question is, do you use it for the front truck or the rear truck?
As you can tell, both trucks (rear and front) turn on a skateboard. On the front truck, the outside wheel needs to be faster during a turn. Conversely, on the rear truck, its the inside wheel that needs to turn faster during a turn.
So if i'm going to use this, which truck would benefit from this?

Also, seems this is up your alley, have you looked into transmission/shifters system. I see some at AndyMark.com, but its quite expensive.

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